Chilled
Cast-iron Shot. Mr Nasmyth's final comments on his inventions and contrivances.
A CANAL
having been formed to connect Edinburgh with the Forth
and Clyde Canal, and so to give a direct waterway
communication between Edinburgh and Glasgow, I heard much
talk about the desirableness of substituting Steam for
Horse power as the means of moving the boats and barges
along the canal. But, as the action of paddle wheels had
been found destructive to the canal banks, no scheme of
that nature could be entertained. Although a tyro in such
matters, I made an attempt to solve the problem, and
accordingly prepared drawings, with a description of my
design, for employing Steam power as the tractive agency
for trains of canal barges, in such a manner as to
obviate all risk of injury to the banks. 
The scheme consisted in laying a chain
along the bottom of the canal, and of passing any part of
its length between three grooved and notched pulleys or
rollers, made to revolve with suitable velocity by means
of a small steam-engine placed in a tug-boat, to the
stern of which a train of barges was attached.
NOTE Had this simple means of
"tugging" vessels through water-ways been
employed in our late attempts to ascend the rapids of the
Nile, some very important results might have issued from
its adoption.
The steam-engine could thus warp
its way along the chain, taking it up between the rollers
of the bow of the tug-boat, and dropping it into the
water at the stern, so as to leave the chain at the
service of the next following tug-boat with its attached
train of barges. By this simple mode of employing the
power of a steam-engine for canal boat traction, all risk
of injury to the banks would be avoided, as the chain
and not the water of the canal was the fulcrum or
resistance which the steam-engine on the tug-boat
operated upon in thus warping its way along the chain;
and thus effectually, without slip or other waste of
power, dragging along the train of barges attached to the
stern of the steam-tug. I had arranged for two separate
chains, so as to allow trains of barges to be conveyed
along the canal in opposite directions, without
interfering with each other.
I submitted a complete set of
drawings, and a full description of my design in all its
details, to the directors of the Canal Company; and I
received a complimentary acknowledgment of them in
writing. But such was the prejudice that existed, in
consequence of the injury to the canal banks resulting
from the use of paddle Wheels, that it extended to the
use of steam power in any form, as a substitute for
ordinary horse traction; and although I had taken every
care to point out the essential difference of my system
(as above indicated) by which all such objections were
obviated, my design was at length courteously declined,
and the old system of horse traction continued.
In 1845 I had the pleasure to see
this simple mode of moving vessels along a definite
course in most successful action at the ferry across the
Hamoaze at Devonport, in which my system of employing the
power of a steam-engine on board the ferry boat, to warp
its way along a submerged chain lying along the bottom of
the channel from side to side of the ferry, was most ably
carried out by my late excellent friend, James Rendell,
Esq., C.E., and is still, I believe, in daily action,
giving every satisfaction.
My kind
friend and patron, Professor Leslie, being engaged in
some investigations in which it was essential to know the
exact comparative total expansion in bulk of metals and
other solid bodies, under the same number of degrees of
heat, mentioned the subject in the course of
conversation. The instrument at that time in use was
defective in principle as well as in construction, and
the results of its application were untrustworthy. As the
Professor had done me the honour to request me to assist
him in his experiments, I had the happiness to suggest an
arrangement of apparatus which I thought might obviate
the sources of error; and, with his approval, I proceeded
to put it in operation.
My
contrivance consisted of an arrangement by means of which
the metal bar or other solid substance, whose total
expansion under a given number of degrees of heat had to
be measured, was in a manner itself converted into a
thermometer. Absolutely equal bulks of each solid were
placed inside a metal tube or vessel, and surrounded with
an exact equal quantity of water at one and the same
normal temperature. A cap or cover, having a suitable
length of thermometer tube attached to it, was then
screwed down, and the water of the index tube was
adjusted to the zero point of the scale attached to it,
the whole being at say 50deg of heat, as the normal
temperature in each case. The apparatus was then heated
up to say 200deg by immersion in water at that
temperature. The expansion of the enclosed bar of metal
or other solid substance under experiment caused the
water to rise above the zero, and it was accordingly so
indicated on the scale attached to the cap tube. In this
way we had a thermometer whose bulb was for the time
being filled with the solid under investigation, -- the
water surrounding it imply acting as the means by which
the expansion of each solid under trial was rendered
visible, and its amount capable of being ascertained and
recorded with the utmost exactness, as the expansion of
the water was in every case the same, and also that of
the instrument itself which was "a constant
quantity."
In this
way we obtained the correct relative amount of expansion
in bulk of all the solid substances experimented upon.
That each bar of metal or other solid substance was of
absolutely equal bulk, was readily ascertained by finding
that each, when weighed in water, lost the exact same
weight.
James Nasmyth's Expansometer, 1826.
My friend, Sir David Brewster, was
so much pleased with the instrument that he published a
drawing and description of it in the Edinburgh
Philosophical Journal, of which he was then editor.
One or
the earliest mechanical contrivances which I made was for
preventing water, in a liquid form, from passing along
with the steam from the boiler to the cylinder of the
steam-engine. The first steam-engine I made was employed
in grinding oil colours for my father's use in his
paintings. When I set this engine to work for the first
time I was annoyed by slight jerks which now and then
disturbed the otherwise smooth and regular action of the
machine. After careful examination I found that these
jerks were caused by the small quantities of water that
were occasionally carried along with the current of the
steam, and deposited in the cylinder, where it
accumulated above and below the piston, and thus produced
the jerks.
In order
to remove the cause of these irregularities, I placed a
considerable portion of the length of the pipe which
conveyed the steam from the boiler to the engine within
the highly heated side flue of the boiler, so that any
portion of water in the liquid form which might chance to
pass along with the steam, might, ere it reached the
cylinder, traverse this highly-heated steam pipe, and, in
doing so, be converted into perfectly dry steam, and in
that condition enter the cylinder. On carrying this
simple arrangement into practice, I found the result to
be in every way satisfactory. The active little
steam-engine thence-forward performed its work in the
most smooth and regular manner.
So far
as I am aware, this early effort of mine at mechanical
contrivance was the first introduction of what has since
been termed "super-heated steam" -- a system
now extensively employed, and yielding important results,
especially in the case of marine steam-engines. Without
such means of supplying dry steam to the engines, the
latter are specially liable to "break-downs,"
resulting from water, in the liquid form, passing into
the cylinders along with the steam.
In
fixing portions of work in the turning-lathe, one of the
most important points to attend to is, that while they
are held with sufficient firmness in order to be turned
to the required form, they should be free from any strain
which might in any way distort them. In strong and
ponderous objects this can be easily accomplished by due
care on the part of an intelligent workman. It is in
operating by the lathe on delicate and flexible objects
that the utmost care is requisite in the process of
chucking, as they are easily strained out of shape by
fastening them by screws and bolts, or suchlike ordinary
means. This is especially the case with disc-like
objects. As I had on several occasions to operate in the
lathe with this class of work I contrived a method of
chucking or holding them firm while receiving the
required turning process, which has in all cases proved
most handy and satisfactory.
This
method consisted of tinning three, or, if need be, more
parts of the work, and laying them down on a tinned
face-plate or chuck, which had been heated so as just to
cause the solder to flow. As soon as the solder is cooled
and set, the chuck with its attached work may then be put
in the lathe, and the work proceeded with until it is
completed. By again heating the chuck, by laying upon it
a piece of red-hot iron, the work, however delicate, can
be simply lifted off, and will be found perfectly free
from all distortion.
I have
been the more particular in naming the use of three
points of attachment to the chuck or face-plate, as that
number is naturally free from any risk of distortion. I
have on so many occasions found the great value of this
simple yet most secure mode of fixing delicate work in
the lathe, that I feel sure that any one able to
appreciate its practical value will be highly pleased
with the results of its employment.
The same
means can, in many cases, be employed in fixing delicate
work in the planing-machine. All that is requisite is to
have a clean-planed wrought-iron or brass fixing-plate,
to which the work in hand can be attached at a few
suitable parts with soft solder, as in the case of the
turning lathe above described.
My
father possessed a very excellent achromatic spy-glass of
2 inches diameter. The object-glass was made by the
celebrated Ramsden. When I was about fifteen I used it to
gaze at the moon, planets, and sun-spots. Although this
instrument revealed to me the general characteristic
details of these grand objects, my father gave me a
wonderful account of what he had seen of the moon's
surface by means of a powerful reflecting telescope of 12
inches diameter, made by Short -- that justly celebrated
pioneer of telescope making. It had been erected in a
temporary observatory on the Calton Hill, Edinburgh.
These descriptions of my father's so fired me with the
desire to obtain a sight of the glorious objects in the
heavens through a more powerful instrument than the
spy-glass, that I determined to try and make a reflecting
telescope which I hoped might in some degree satisfy my
ardent desires.
I
accordingly searched for the requisite practical
instruction in the pages of the Encyclopedia
Britannica, and in other books that professed to give
the necessary technical information on the subject. I
found, however, that the information given in books -- at
least in the books to which I had access was meagre and
unsatisfactory. Nevertheless I set to work with all
earnestness, and began by compounding the requisite alloy
for casting a speculum of 8 inches diameter. This alloy
consisted of 32 parts of copper, 15 parts of grain tin,
and 1 part of white arsenic. These ingredients, when
melted together, yielded a compound metal which possessed
a high degree of brilliancy. Having made a wooden pattern
for my intended 8-inch diameter speculum, and moulded it
in sand, I cast this my first reflecting telescope
speculum according to the best book instructions.
I allowed my casting to cool in the mould in the slowest
possible manner; for such is the excessive brittleness of
this alloy (though composed of two of the toughest of
metals) that in any sudden change of temperature, or want
of due delicacy in handling it, it is very apt to give
way, and a fracture more or less serious is sure to
result. Even glass, brittle though it be, is strong in
comparison with speculum metal of the above proportions,
though, as I have said, it yields the most brilliant
composition.
Notwithstanding
the observance of all due care in respect of the
annealing of the casting by slow cooling, and the utmost
care and delicate handling of it in the process of
grinding the surface into the requisite curve and
smoothness suitable to receive the final polish, -- I was
on more than one occasion inexpressibly mortified by the
sudden disruption and breaking up of my speculum. Thus
many hours of anxious care and labour proved of no avail.
I had to begin again and proceed da capo. I
observed, however, that the surplus alloy that was left
in the crucible, after I had cast my speculum, when again
melted and poured out into a metal ingot mould, yielded a
cake that, brittle though it might be, was yet strong in
comparison with that of the speculum cast in the sand
mould; and that it was also, judging from the fragments
chipped from it, possessed of even a higher degree of
brilliancy.
The
happy thought occurred to me of substituting an open metal
mould for the closed sand one. I soon had the
metal mould ready for casting. It consisted of a base
plate of cast iron, on the surface of which I placed a
ring or hoop of iron turned to fully the diameter of the
intended speculum, so as to anticipate the contraction of
the alloy. The result of the very first trial of this
simple metal mould was most satisfactory. It yielded me a
very perfect casting: and it passed successively through
the ordeal of the first rough grinding, and eventually
through the processes of polishing, until in the end it
exhibited a brilliancy that far exceeded that of the sand
mould castings.
The only
remaining difficulty that I had to surmount was the risk
of defects in the surface of the speculum. These
sometimes result from the first splash of the
melted metal as it is poured into the ring mould. The
globules sometimes got oxidised before they became
incorporated with the main body of the inflowing molten
alloy: and dingy spots in the otherwise brilliant alloy
were thus produced. I soon mastered this, the only
remaining source of defect, by a very simple arrangement.
In place of pouring the melted alloy direct into the ring
mould, I attached to the side of it what I termed a
"pouring pocket;" which communicated with an
opening at the lower edge of the ring, and by a
self-acting arrangement by which the mould plate was
slightly tilted up, the influx of the molten alloy
advanced in one unbroken tide. As soon as the entire
surface of the mould plate was covered by the alloy, its
weight overcame that of my up-tilting counterpoise, and
allowed the entire apparatus to resume its exact level.
The resulting speculum was, by these simple arrangements,
absolutely perfect in soundness. It was a perfect
casting, in all respects worthy of the care and labour
which I invested in its future grinding and polishing,
and enabled it to perform its glorious duties as the
grand essential part of a noble reflecting telescope!
A.
Chill plate of cast iron turned to the curve of
the speculum
B.
Turned hoop of wrought iron with opening at O.
C.
Pouring pocket.
D.
Counterpoise, By which the chill plate is tilted
up
The
largest figure in the engraving is the annealing
tub of cast iron filled with sawdust, where the
speculum is placed to cool as slowly as possible.
The rationale of the strength
of specula cast in this metal mould system, as
compared with the treacherous brittleness of
those cast in sand moulds, arises simply from the
consolidation of the molten metal pool taking
place first at the lower surface, next the metal
base of the mould -- the yet fluid alloy above
satisfying the contractile requirements of that
immediately beneath it; and so on in succession,
until the last to consolidate is the top or upper
stratum. Thus all risk of contractile tension,
which is so dangerously eminent and inherent in
the case of sand-mould castings, made of so
exceedingly brittle an alloy as that of speculum
metal, is entirely avoided. By the employment of
these simple and effective improvements in the
art of casting the specula for reflecting
telescopes, and also by the contrivance and
employment of mechanical means for grinding and
polishing them, I at length completed my first
8-inch diameter speculum, and mounted it
according to the Newtonian plan. I was most amply
rewarded for all the anxious labour I had gone
through in preparing it, by the glorious views it
yielded me of the wonderful objects in the
heavens at night. My enjoyment was in no small
degree enhanced by the pleasure it gave to my
father, and to many intimate friends. Amongst
these was Sir David Brewster, who took a most
lively and special interest in all my labours on
this subject.
In
later years I resumed my telescope making
enjoyments, as a delightful and congenial
relaxation from the ordinary run of my business
occupations. I constructed several reflecting
telescopes, of sizes from 10-inch to 20-inch
diameter specula. I had also the pleasure of
assisting other astronomical friends, by casting
and grinding specula for them. Among these I may
mention my late dear friend William Lassell, and
my excellent friend Warren de la Rue, both of
whom have indelibly recorded their names in the
annals of astronomical science. I know of no
subject connected with the pursuit of science
which so abounds with exciting and delightful
interest as that of constructing reflecting
telescopes. It brings into play every principle
of constructive art, with the inexpressibly
glorious reward of a more intimate acquaintance
with the sublime wonders of the heavens, I
communicated in full detail all my improvements
in the art of casting, grinding, and polishing
the specula of reflecting telescopes, to the
Literary and Philosophical Society of Manchester,
illustrating my paper with many drawings. But as
my paper was of considerable length, and as the
illustrations would prove costly to engrave, it
was not published in the Society's Transactions.
They are still, however, kept in the library for
reference by those who take a special interest in
the subject.
While
assisting Mr. Maudslay in the execution of a
special piece of machinery, in which it became
necessary to have some holes drilled in rather
inaccessible portions of the work in hand, and
where the employment of the ordinary drill was
impossible, it occurred to me that a flexible
shaft, formed of a closely coiled spiral of steel
wire, might enable us to transmit the requisite
rotary motion to a drill attached to the end of
this spiral shaft. Mr. Maudslay was much pleased
with the notion, and I speedily put it in action
by a close coiled spiral wire of about two feet
in length.
This
was found to transmit the requisite rotary motion
to the drill at the end of the spiral with
perfect and faithful efficiency. The difficulty
was got over, to Mr. Maudslay's great
satisfaction.
So
far as I am aware, such a mode of transmitting
rotary motion was new and original. The device
was useful, and proved of essential service in
other important applications. By a suitably close
coiled spiral steel wire I have conveyed rotary
motion quite round an obstacle, such as is
indicated in the annexed figure.
It
has acted with perfect faithfulness from the
winch handle at A to the drill at B. Any
ingenious mechanic will be able to appreciate the
value of such a flexible shaft in many
applications . Four years ago I saw the same
arrangement in action at a dentist's
operating-room, when a drill was worked in the
mouth of a patient to enable a decayed tooth to
be stopped. It was said to be the last thing out
in "Yankee notions." It was merely a
replica of my flexible drill of 1829.
The
fastening of wheels and belt pulleys to shafts,
so as to enable them to transmit rotary motion,
is one of the most frequently-recurring processes
in the construction of machinery. This is best
effected by driving a slightly tapered iron or
steel wedge, or "key" as it is
technically termed, into a corresponding recess,
or flat part of the shaft, so that the wheel and
shaft thus become in effect one solid structure.
The
old mode of cutting such key-grooves in the eyes
of wheels was accomplished by the laborious and
costly process of chipping and filing. Maudslay's
mortising machine, which he contrived for the
Block machinery, although intended originally to
operate upon wood, contained all the essential
principles and details required for acting on
metals. Mr. Richard Roberts, by some excellent
modifications, enabled it to mortise or cut out
the key-grooves in metal wheels, and this method
soon came into general use. This machine
consisted of a vertical slide bar, to the lower
end of which was attached the steel mortising
tool, which received its requisite up and down
motion from an adjustable crank, through a
suitable arrangement of the gearing. The wheel to
be operated upon was fixed to a slide-table, and
gradually advanced, so as to cause the mortising
tool to take successive cuts through the depth of
the eye of the wheel, until the mortise or
key-groove had attained its required depth.
The
only drawback to this admirable machine was that
its service was limited in respect to admitting
wheels whose half diameter did not exceed the
distance from the back of the jaw of the machine
to the face of the mortise tool; so that to give
to this machine the requisite rigidity and
strength to resist the strain on the jaw, due to
the mortising of the key-grooves, in wheels of
say 6 feet diameter, a more massive and cumbrous
frame work was required, which was most costly in
space as well as in money.
In
order to obviate this inconvenience, I designed
an arrangement of a key-groove mortising machine.
It was capable of operating upon wheels of any
diameter, having no limit to it capacity in that
respect. 'It was, at the same time, possessed in
respect of the principle on which it was
arranged, of the power of taking a much deeper
cut, there being an entire absence of any source
of springing or elasticity in its structure. This
not only enabled the machine to perform its work
with more rapidity, but also with more precision.
Besides, it occupied much less space in the
workshop, and did not cost above one-third of the
machines formerly in use. It gave the highest
satisfaction to those who availed themselves of
its effective Services.
A
comparison of Fig. 1 -- which represents the
general arrangement of the machine in use
previous to the introduction of mine -- with that
of Fig. 2, may serve to convey some idea of their
relative sizes. Fig. 1 shows a limit to the
admission of wheels exceeding 6 feet diameter,
Fig. 2 shows an unlimited capability in that
respect.
One
of the most numerous details in the structure of
all classes of machines is the bolts which serve
to hold the various parts together. As it is most
important that each bolt fits perfectly the hole
it belongs to, it is requisite that each bolt
should, by the process of turning, be made
perfectly cylindrical. In preparing such bolts,
as they come from the forge, in order to undergo
the process of turning, they have to be
"centred;" that is, each end has to
receive a hollow conical indent, which must agree
with the axis of the bolt. To find this in
the usual mode, by trial and frequent error, is a
most tedious process, and consumes much valuable
time of the workman as well as his lathe.
In order
to obviate the necessity for this costly process,
I devised the simple instrument, a drawing of
which is annexed. The use of this enabled any boy
to find and mark with absolute exactness and
rapidity the centres of each end of bolts, or
suchlike objects. All that was required was to
place the body of the bolt in the V-shaped
supports, and to gently cause it to revolve,
pressing it longitudinally against the
steel-pointed marker, which scratched a neat
small circle in the true centre or axis of the
bolt. This small circle had its centre easily
marked by the indent of a punch, and the work was
thus ready for the lathe. This humble but really
important process was accomplished with ease,
rapidity, and great economy.
The
desire to make the pistons of steam-engines and
air-pump buckets of condensing engines perfectly
steam and water tight has led to the contrivance
of many complex and costly constructions for the
purpose of packing them. When we take a
commonsense view of the subject, we find that in
most cases the loss of power resulting from the
extra friction neutralises the expected saving.
This is especially the case with the air-pump
bucket of a condensing steam-engine, as it is in
reality much more a water than an air
pump. But when it is constructed with a deep
well-fitted bucket, entirely without packing, the
loss sustained by such an insignificant amount of
leakage as may occur from the want of packing is
more than compensated by the saving of power
resulting from the total absence of friction.
The
first condensing steam-engine to which I applied
an air-pump bucket, entirely without packing,
was the forty horsepower engine, which I
constructed for the Bridgewater Foundry. It
answered its purpose so well that, after twenty
years' constant working , the air-pump cover was
taken off, out of curiosity, to examine the
bucket, when it was found in perfect order. This
system, in which I dispensed with the packing for
air-pump buckets of condensing steam-engines, I
have also applied to the pistons of the steam
cylinders, especially those of high-pressure
engines of the smaller vertical construction, the
stroke of which is generally short and rapid.
Provided the cylinder is bored true, and the
piston is carefully fitted, and of a considerable
depth in proportion to its diameter, such pistons
will be found to perform perfectly all their
functions, and with a total absence of friction
as a direct result of the absence of packing. By
the aid of our improved machine tools, cylinders
can now be bored with such perfect accuracy, and
the pistons be fitted to them with such absolute
exactness, that the small quantity of water which
the steam always deposits on the upper side of
the piston, not only serves as a frictionless
packing, but also serves as a lubricant of the
most appropriate kind. I have applied the same
kind of piston to ordinary water-pumps, with
similar excellent results. In most cases of right
packed pistons we spend a shilling -- to save
sixpence -- a not unfrequent result of
"so-called" refined improvements.
The
mode referred to consists in giving a rapid
"switch" motion to a pencil upon a
piece of paper, or a cardboard, or a smooth metal
plate; and then cutting out the curve so
produced, and employing it as a pattern or
"template," to enable copies to be
traced from it. When placed at equal distances,
and at equal angles on each side of a central
line, so as to secure perfect symmetry of form
according to the nature of the required design,
the beauty of these "instantaneous"
curves, as I term them, arises from the entire
absence of any sudden variation in their
course. This is due to the momentum of the hand
when "switching" the pencil at a high
velocity over the paper. By such simple means was
the beautiful curve produced, which is given on
the following page. It was produced "in a
twinkling," if I may use the term to express
the rapidity with which it was
"switched." The chief source of the
gracefulness of these curves consists in the
almost imperceptible manner in which they pass in
their course from one degree of curvature into
another. I have had the pleasure of showing this
simple mode of producing graceful curves to
several potters, who have turned the idea to good
account. The illustrative figures on the next
page have all been drawn from
"templates" whose curves were
"switched" in the manner of Fig. A.
Although
the introduction of the planing machine into the
workshops of mechanical engineers yielded results
of the highest importance in perfecting and
economising the production of machinery
generally, yet, as the employment of these
valuable machine tools was chiefly intended to
assist in the execution of the larger parts of
machine manufacture, a very considerable
proportion of the detail parts still continued to
be executed by hand labour, in which the chisel
and the file were the chief instruments employed.
The results were consequently very
unsatisfactory, both as regards inaccuracy and
costliness.
With
the desire of rendering the valuable services of
the Planing Machine applicable to the smallest
detail parts of machine manufacture, I designed a
simple and compact modification of it, such as
should enable any attentive lad to execute all
the detail parts of the machines in so unerring
and perfect a manner as not only to rival the
hand work of the most skilful mechanic, but also
at such a reduced cost as to place the most
active hand workman far into the background. The
contrivance I refer to is usually known as
"Nasmyth's Steam Arm." None but those
who have had ample opportunities of watching the
process of executing the detail parts of
machines, can form a correct idea of the great
amount of time that is practically wasted and
unproductive, even when highly-skilled and
careful workmen are employed. They have so
frequently to stop working, in order to examine
the work in hand, to use the straight edge, the
square, or the calipers, to ascertain whether
they are "working correctly." During
that interval, the work is making no progress:
and the loss of time on this account is not less
than one-sixth of the working hours, and
sometimes much more; though all this lost time is
fully paid for in wages. 
Apparatus
for enabling the machine to execute segmented
work
But
by the employment of such a machine as I
describe, even when placed under the
superintendence of well-selected intelligent
lads, in whom the faculty of good sight and
nicety of handling is naturally in a high state
of perfection, any deficiency in their physical
strength is amply compensated by these
self-acting machines. The factory engine supplies
the labour or the element of Force, while the
machines perform their work with practical
perfection. The details of machinery are thus
turned out with geometrical accuracy, and are in
the highest sense fitted to perform their
intended purposes.
It consists of a
lever E, moving on a stud-pin S, attached to the
back of the head stock of the lathe T. This lever
carries two wheels of equal diameter marked B and
G. These wheels can pitch into a corresponding
wheel A, fixed on the back end of the lay
spindle. When the handle of the lever E is
depressed (as seen in the drawing) the wheel B is
in gear with wheel A. while C is in gear with the
slidescrew wheel D, and so moves the slide (say from
the Head Stock of the lathe). On the other hand,
when the lever E is elevated in position E",
wheel B is taken out of gear with A, while G is
put in gear with A, and B is put in gear with D;
and thus the Slide is caused to move towards
the Head Stock of the lathe. Again, where it is
desired to arrest the motion of the Slide
altogether, or for a time, as occasion may
require, the lever handle is put into the
intermediate position E', which entirely severs
the communication between A and D, and so arrests
the motion of the slide. This simple contrivance
effectually served all its purposes, and was
adopted by many machine tool-makers and
engineers.
A
frequent cause of undue friction and heating of
rapidly rotating machinery arises from some
inaccuracy or want of due parallelism between the
rotating shaft or spindle and its bearing. This
is occasioned in most cases by some accidental
change in the level of the supports of the
bearings. Many of the bearings are situated in
dark places, and cannot be seen. There are others
that are difficult of access -- as in the case of
bearings of screw-propeller shafts. Serious
mischief may result before the heating of the
bearing proclaims its dangerous condition. In
some cases the timber work is set on fire, which
may result in serious consequences.
In
order to remove the cause of such serious
mischief, I designed an arrangement of bearing,
which enabled it, and the shaft working in it, to
mutually accommodate themselves to each other
under all circumstances, and thus to avoid the
danger of a want of due and mutual parallelism in
their respective axes. This arrangement consisted
in giving to the exterior of the bearing a
spherical form, so as, within moderate
limits, to allow it to accommodate itself to any
such changes in regard to mutual parallelism, as
above referred to. In other cases, I employed
what I may call Rocking centres, on which
the Pedestal or "Plumber Block" rested;
and thus supplied a self-adjusting means for
obviating the evils resulting from any accidental
change in the proper relative position of the
shaft and its bearing. In all cases in which I
introduced this arrangement, the results were
most satisfactory.
In
the case of the bearings of Blowing Fans, in
which the rate of rotation is naturally
excessive, a spherical resting-place for the
bearings enabled them to keep perfectly cool at
the highest speed. This was also the case in the
driving apparatus for machine tools, which is
generally fixed at a considerable height above
the machine. These spherical or self-adjusting
bearings were found of great service. The
apparatus, being generally out of convenient
reach, is apt to get out of order unless duly
attended to. But, whether or not, the saving of
friction is in itself a reason for the adoption
of such bearings. This may appear a trifling
technical matter of detail; but its great
practical value must be my excuse for mentioning
it.
My
invention was made at this early date, long
before the attack by the steam-ram Merrimac
upon the Cumberland, and other ships, in
Hampton Roads, United States. I brought my plans
and drawings under the notice of the Admiralty in
1845 ; but nothing was done for many years. Much
had been accomplished in rendering our ships
shot-proof by the application of iron plates; but
it appeared to me that not one of them could
exist above water after receiving on its side a
single blow from an iron-plated steam-ram of 2000
tons. I said, in a letter to the Times,
"As the grand object of naval warfare is the
destruction by the most speedy mode of the ships
of the enemy, why should we continue to attempt
to attain this object by making small holes in
the hull of the enemy when, by one single
masterly crashing blow from a steam ram,
we can crush in the side of any armour-plated
ship, and let the water rush in through a hole,
'not perhaps as wide as a church door or as deep
as a well, but 'twill serve'; and be certain to
send her below water in a few minutes.
NOTE
In these days of armour-clad warships, when
plates of enormous thickness are relied on as
invulnerable, our Naval Constructors appear to
forget that the actual structural strength of
such ships depends on the backing of the
plates, which, be it ever so thick, would yield
to the cramming blow of a moderate-sized Ram. I published
my description of the steam ram and its apparatus
in the Times of January 1853, and again
addressed the Editor on the subject in April
1862. General Sir John Burgoyne took up the
subject, and addressed me in the note at the foot
of this page.[note:
The
following is the letter of General Sir John
Burgoyne: WAR OFFICE, PALL MALL, LONDON, 8th
April 1862.
"General
Sir John Burgoyne presents his compliments to Mr.
Nasmyth, and was much pleased to find, by Mr.
Nasmyth's letter in the Times of this day,
certain impressions that he has held for some
time confirmed by so good an authority. "A
difficulty seems to be anticipated by many that a
steamer used as a ram with high velocity, if
impelled upon a heavy ship, would, by the
revulsion of the sudden shock, be liable to have
much of her gear thrown entirely out of order,
parts displaced, and perhaps the boilers burst.
Some judgment, however, may be formed on this
point by a knowledge of whether such
circumstances have occurred on ships suddenly
grounding; and even so, it may be a question
whether so great a velocity is necessary.
"An accident occurred some twenty years ago,
within Sir John Burgoyne's immediate cognisance,
that has led him particularly to consider the
great power of a ship acting as a ram. A somewhat
heavy steamer went, by accident or mismanagement,
end on to a very substantial wharf wall in
Kingstown Harbour, Dublin Bay. Though the force
of the blow was greatly checked through the
measures taken for that purpose, and indeed so
much so that the vessel itself suffered no very
material injury, yet several of the massive
granite stones of the facing were driven some
inches in, showing the enormous force used upon
them. "Superior speed will be very essential
to the successful action of the ram; but by the
above circumstance we may assume that even a
moderate speed would enable great effects to be
produced, at least on any comparatively weak
point of even ironclad ships, such as the
rudder."]
In June
1870, I received a letter from Sir E. J. Reed,
containing the following extracts:-- "I was
aware previously that plans had been proposed for
constructing unarmoured steam rams, but I was not
acquainted with the fact that you had put forward
so well-maturerd a scheme at so early a date ;
and it has given me much pleasure to find that
such is the case. It has been a cause both of
pleasure and surprise to me to find that so long
ago you incorporated into a design almost all the
features which we now regard as essential to
ramming efficiency -- twin screws and moderate
dimensions for handiness, numerous water-tight
divisions for safety, and special strengthenings
at the bow. Facts such as these deserve to be put
on record. . . . Meanwhile accept my
congratulations on the great skill and foresight
which your ram-design displays."
Collisions
at sea unhappily afford ample evidence of the
fatal efficiency of the ramming principle. Even
ironclad ships have not been able to withstand
the destructive effect. The Vanguard and
the Kurfürst now lie at the bottom of the
sea in consequence of an accidental
"end-on" ram from a heavy ship going at
a moderate velocity. High speed in a Steam Ram is
only desirable when the attempt is made to
overtake an enemy's ship; but not necessary for
doing its destructive work. A crash on the thick
plates of the strongest Ironclad, from a Ram of
2000 tons at the speed of four miles an hour,
would drive them inwards with the most fatal
results.
The
late Mr. Wicksteed, engineer of the East London
Water Company, having stated to me the
inconvenience which had been experienced from the
defects in respect of water-tightness, as well as
the difficulty of opening and closing the valves
of the main water-pipes in the streets, I turned
my attention to the subject. The result was my
contrivance of a double-faced wedge-shaped
sluice-valve, which combined the desirable
property of perfect water-tightness with ease of
opening and closing the valve.
This
was effected by a screw which raised the valve
from its bearings at the first partial turn of
the screw, after which there was no further
resistance or friction, except the trifling
friction of the screw in its nut on the upper
part of the sluice-valve. When screwed down
again, it closed simultaneously the end of the
entrance pipe and that of the exit pipe attached
to the valve case in the most effective manner.
Mr.
Wicksteed was so much pleased with the simplicity
and efficiency of this valve that he had it
applied to all the main pipes of his Company.
When its advantages became known, I received many
orders from other water companies, and the valves
have since come into general use. The prefixed
figure will convey a clear idea of the
construction. The wedge form of the double-faced
valve is conspicuous as the characteristic
feature of the arrangement. NOTE At
a meeting of the Institution of Civil Engineers,
May 23, 1883, when various papers were read on
Waterworks, Mr. H. I. Marten observed in the
course of the discussion:-- "It has been
stated in Mr. Gamble's paper (on the waterworks
of Port Elizabeth) that the sluice valves are of
the usual pattern. The usual patterns of the
present day are in wonderful advance of those of
thirty or forty years since. The great
improvement originated with the introduction of
'the double-faced sluice-cock.' This sluice-cock,
which had now superseded every other description,
was the creation of Mr. James Nasmyth's inventive
genius. Mr. Marten said he well remembered the
first reception of this useful invention, as he
happened at that time to be a pupil of Mr. Thomas
Wicksteed. He was present when Mr. Wicksteed
explained to Mr. Nasmyth the want he had
experienced of a sluice-cock for Waterworks
purposes, which should shut and remain perfectly
tight against a pressure coming from either side.
Mr. Marten had a lively recollection of the
instantaneous rapidity with which Mr. Nasmyth not
only grasped but provided for the requirement; so
that almost by the time Mr. Wicksteed had
completed the statement of his want, Mr. Nasmyth
had drawn upon the back of an old letter a rough
sketch of the first double-faced sluice-cock; and
in less than an hour had converted this rough
sketch into a full-sized working drawing; in the
preparation of which it fell to Mr. Marten's lot
to have the honour to assist. In his
'Autobiography' Mr. Nasmyth referred to the
conversation with Mr. Wicksteed, and introduced a
print of the drawing made upon the occasion. The
invention has been of the greatest use to the
Waterworks Engineer, especially in connection
with the constant supply system, in which it
frequently happened that the pressure was
sometimes against one face of the sluice-cock,
and sometimes against the other." -- See Proceedings
and Discussions of the Institution of Civil
Engineers, 1883, pp. 88, 89.
Being
under the impression that there are many
processes in the manufacturing arts, in which a
perfectly controllable compressing power of vast
potency might be serviceable, I many years ago
prepared a design of an apparatus of a very
simple and easily executed kind, which would
supply such a desideratum. It was possessed of a
range of compressing or squeezing power,
which far surpassed anything of the kind that had
been invented. As above said, it was perfectly
controllable; so as either to yield the most
gentle pressure, or to possess the power of
compressing to upwards of twenty thousand tons;
the only limit to its power being in the
materials employed in its construction.
The
principle of this enormously powerful compressing
machine is similar to that of the Hydraulic
Press; the difference consisting principally in
the substitution of what I term a Hydraulic
Mattress in place of the cylinder and ram of the
ordinary hydraulic press. The Hydraulic Mattress
consists of a square or circular water-tight
vessel or flat bag formed of 1/2-inch thick iron
or steel plates securely riveted together; its
dimensions being, say 15 feet square by 3 feet
deep, and having semicircular sides, which form
enables the upper flat part of the Mattress to
rise say to the extent of 6 inches, without any
injury to the riveted joints, as such a rise or
alteration of the normal form of the semicircular
sides would be perfectly harmless, and not exceed
their capability of returning to their normal
curve when the 6-inch rise was no longer
necessary, and the elevating pressure removed.
The
action of this gigantic press is as follows. The
Mattress A A having been filled with water, an
additional quantity is supplied by a force pump,
capable of forcing in water with a pressure of
one ton to the square inch ; thus acting on an
available surface of at least 144 square feet
surface -- namely, that of the upper flat surface
of the Mattress. It will be forced up by no less
a pressure than twenty thousand tons, and
transfer that enormous pressure to any article
that is placed between the rising table of the
press and the upper table. When any object less
thick than the normal space is required to
receive the pressure, the spare space must be
filled with a suitable set of iron flat blocks,
so as to subject the article to be pressed to the
requisite power. As
before stated, there may be many processes in the
manufacturing arts in which such an enormous
pressure may be useful; and this can be
accomplished with perfect ease and certainty. I
trust that this account of the principles and
construction of such a machine may suggest some
employment worthy of its powers. In the general
use of the Mattress press, it would be best to
supply the pressure water from an accumulator,
which should be kept constantly full by the
action of suitable pumps worked by a small
steam-engine. The great press would require the
high-pressure water only now and then; so that it
would not be necessary to wait for the small pump
to supply the pressure water when the Mattress
was required to be in action.
The
letter X shows how Screws are frequently made
when tapped in the old mode; the letter T as they
are always made when the Tapping Square is
employed.
In
executing an order for twenty locomotive engines
for the Great Western Railway Company, there was
necessarily a repetition of detail parts. Many of
them required the labour of the most skilful
workmen, as the parts referred to did not admit
of their being executed by the lathe or
planing-machine in their ordinary mode of
application. But the cost of their execution by
hand labour was so great, and the risk of
inaccuracy was so common (where extreme accuracy
was essential), that I had recourse to the aid of
special mechanical contrivances and machine tools
for the purpose of getting over the difficulty.
The annexed illustration has reference to only
one class of objects in which I effected great
saving in the production, as well as great
accuracy in the work. It refers to a contrivance
for producing by the turning-lathe the eighty
bands of the eccentrics for these twenty engines.
Being of a segmental form, but with a projection
at each extremity, which rendered their
production and finish impossible by the ordinary
lathe, I bethought me of applying what is termed
the mangle motion to the rim of a face
plate of the lay, with so many pins in it as to
give the required course of segmental motion for
the turning tool to operate upon, between the
projections C C in the illustration.
I
availed myself of the limited to-and-fro
horizontal motion of the shaft of the mangle
motion wheel, as it, at each end of the row of
pegs - in the face plate (when it passes from the
exterior to the interior range of them) in giving
the feed motion to the tool in; the slide rest,
"turned" the segmental exterior of the
eccentric hoops. This it did perfectly, as the
change of position of the small shaft occurred at
the exact time when the cut was at its
termination, -- that being the correct moment to
give the tool "the feed, or advance for the
taking of the next cut. The saving, in respect to
time, was 10 to 1 in comparison with the
same amount of work done by hand labour; while
the "truth" or correctness of the work
done by this handy little application of the
turning-lathe was absolutely perfect I have been
the more particular in my allusion to this
contrivance, as it is applicable to any lathe,
and can perform work which no lathe without it
can accomplish. The unceasing industry of such
machines is no small addition to their
attractions, in respect to the production of
unquestionably accurate work.
The chief novelty in
this swivel joint is the manner in which the
packing of the joints is completely enclosed,
thereby rendering them perfectly and permanently
watertight.
If a Fan be
constructed on this common-sense principle, we
shall secure the maximum of blast from the
minimum of driving power. And not only so; but
the humming sound -- so disagreeable an
accompaniment to the action of the Fans (being
caused by the successive sudden escape of the air
from each compartment as it comes opposite the
space where it can discharge its confined block
of air) -- will be avoided. When the outer case
of a Fan is formed on the expanding or spiral
principle, as above described, all these
important advantages will attend its use. As the
inward current of air rushes in at the circular
openings on each side of the Fan-case, and would
thus oppose each other if there was a free
communication between them, this is effectually
obviated by forming the rotating portion of the
fan by a disc of iron plate, which prevents the
opposite in-rushing currents from interfering
with each other, and at the same time supplies a
most substantial means of fastening the blades,
as they are conveniently riveted to this central
disc. On the whole, this arrangement of machinery
supplies a most effective "Noiseless Blowing
Fan."
The
frequency of disastrous colliery explosions
induced me to give my attention to an improved
method for ventilating coal mines. The practice
then was to employ a furnace, placed at the
bottom of the upcast shaft of the coal-pit, to
produce the necessary ventilation. This practice
was highly riskful. It was dangerous as well as
ineffective. It was also liable to total
destruction when an explosion occurred, and the
means of ventilation were thus lost when it was
most urgently required. The ventilation of mines
by a current of air forced by a Fan into the
workings, had been proposed by a German named
George Agricola, as far back as 1621. The
arrangement is found figured in his work entitled
De Re Metalicat, p. 162. But in all cases
in which this system of forcing air
through the workings and passages of a mine has
been tried, it has invariably been found
unsuccessful as a means of ventilation.
As
all rotative Blowing Fans draw in the air at
their centres, and expel it at their
circumference, it occurred to me that if we were
to make a communication between the upcast shaft
of the mine and the centre or suctional
part of the Fan closing the top of the upcast
shaft, a Fan so arranged would draw out the foul
air from the mine, and allow the fresh air to
descend by the downcast shaft, and so traverse
the workings. And as a Suction Fan so placed
would be on the surface of the ground, and quite
out of the way of any risk of injury -- being
open to view and inspection at all times -- we
should thus have an effective and trustworthy
means for thorough ventilation.
Having
communicated the design for my Direct Action
Suction Fan for coal-pit ventilation to the Earl
Fitzwilliam, through his agent Mr. Hartop, in
1850, his lordship was so much pleased with it
that I received an order for one of 14 feet
diameter, for the purpose of ventilating; one of
his largest coalpits. I arranged the steam-engine
which gave motion to the large Fan, so as to be a
part of it; and by placing the crank of the
engine on the end of the Fan-shaft, the engine
transferred its power to it in the most simple
and direct manner. The high satisfaction which
this Ventilating Fan gave to the Earl and to all
connected with his coal-mines, led to my
receiving orders for several of them. I took
out no patent for the invention, but sent
drawings and descriptions to all whom I knew to
be interested in coalmine ventilation. I read a
paper on the subject, and exhibited the necessary
drawings, at the meeting of the British
Association at Ipswich in 1851. These were
afterwards published in the Mining Journal.
The consequence is that many of my Suction
Ventilating Fans are now in successful action at
home and abroad.
One
of the most important processes in connection
with the production of the details of machinery,
and other purposes in which malleable iron is
employed, is that termed welding, namely,
when more or less complex forms are, so to speak,
"built up" by the union of suitable
portions of malleable iron united and
incorporated with each other in the process of
welding. This consists in heating the parts which
we desire to unite to a white heat in a
smith's forge fire, or in an air furnace, by
means of which that peculiar adhesive
"wax-like" capability; of sticking
together is induced, -- so that when the several
parts are forcibly pressed into close contact by
blows of a hammer, their union is rendered
perfect.
But
as the intense degree of heat which is requisite
to induce this adhesive quality is accompanied by
the production of a molten oxide of iron that
clings tenaciously to the white-hot surfaces of
the iron, the union will not be complete unless
every particle of the adhesing molten scoriae is
thoroughly discharged and driven out from between
the surfaces we desire to unite by welding. If by
any want of due care on the part of the smith,
the surfaces be concave or have hollows in
them, the scoriae will be sure to lurk in the
recesses, and result in a defective welding of a
most treacherous nature. Though the exterior
may display no evidence of the existence of this
fertile cause of failure, yet some undue or
unexpected strain will rend and disclose the
shut-up scoriae, and probably end in some fatal
break-down. The annexed figures will perhaps
serve to render my remarks on this truly
important subject more clear to the reader.
Fig.1
represents an imperfectly prepared surface of two
pieces of malleable iron about to be welded. The
result of their concavity of form is that the
scoriae are almost certain to be shut up in the
hollow part, -- as the pieces will unite first at
the edges and thus include the scoriae,
which no amount of subsequent hammering will ever
dislodge. They will remain lurking between, as
seen in Fig.2. Happily, the means of obviating
all such treacherous risks are as simple as they
are thoroughly effective. All that has to be done
to render their occurrence next to impossible is
to give to the surfaces we desire to unite by
welding a convex form as represented in
Fig. 3; the result of which is that we thus
provide an open door for the scoriae to escape
from between the surfaces, -- as these unite
first in the centre, as due to the convex form,
and then the union proceeds outwards, until every
particle of scoriae is expelled, and the union is
perfectly completed under the blows of the hammer
or other compressing agency. Fig. 4 represents
the final and perfect completion of the welding,
which is effected by this common-sense and simple
means, -- that is, by giving the surfaces a convex
form instead of a concave one. When I
was called by the Lords of the Admiralty in 1846
to serve on a Committee, the object of which was
to investigate the causes of failure in the
wrought-iron smith work of the navy, many sad
instances came before us of accidents which had
been caused by defective welding, especially in
the vitally important articles of Anchors and
Chain Cables. In the case of the occasional
failure of chain cables, the cause was generally
assigned to defective material; but circumstances
led me to the conclusion that it was a question
of workmanship or maltreatment of what I knew to
be of excellent material. I therefore instituted
a series of experiments which yielded conclusive
evidence upon the subject; and which proved that defective
welding was the main and chief cause of
failure. In order to prove this, several
apparently excellent cables were, by the aid of
"the proving machine," pulled to
pieces, link by link, and a careful record was
kept of the nature of the fracture. The result
was, that out of every 100 links pulled asunder
80 cases clearly exhibited defective welding;
while only 20 were broken through the clear sound
metal. This yielded a very important lesson to
those specially concerned.
In
connection with my Steam Hammer, when employed in
forging great cylindrical shafts, I introduced
what I termed my V anvil. Its employment has most
importantly contributed to secure perfect
soundness in such class of forgings.
In
the old system of forging cylindrical shafts, the
bar was placed upon a flat-faced anvil. The
effect of each blow of the hammer upon the work
was to knock the shaft into an oval form (see
Fig. 1); and the inevitable result of a
succession of such blows was destruction of the
soundness of the centre or axis of the shaft.
In
order to remedy this grave defect, arising from
the employment of a flat-faced anvil, I
introduced my V anvil face (see Fig. 2), the
effect of which was, that the dispersive
action of the blow of the hammer was changed into
a converging action, which ensured the
perfect soundness of the work; while the V or
fork-like form of the angle face kept the work
steadily under the centre of the hammer, allowing
the scale or scoriae to fall into the apex or
bottom of the V, which thus passed away, leaving
the faces of the angle quite clear. This
simple and common-sense improvement was eagerly
and generally adopted, and has been productive of
most satisfactory and important results.
Having
been on several occasions called to investigate
the causes of steam boiler explosions, my
attention was naturally directed to the condition
of the Safety Valve. I found the construction of
them in many cases to be defective in principle
as well as in mechanical details; resulting
chiefly from the employment of a conical
form in the valve, which necessitated the use of
a guide spindle to enable it to keep in correct
relative position to its corresponding conical
seat, as seen at A in Fig. 1. As this guide
spindle is always liable to be clogged with the
muddy deposit from the boiling water, which
yields a very adhesive encrustation, the result
is a very riskful tendency to impede the free
action of the Safety Valve, and thereby prevent
its serving its purpose.
With
a view to remove all such causes of uncertainty
in the action of this vitally important part of a
steam boiler I designed a Safety Valve, having a spherical
valve and corresponding seat, as seen in B C,
Fig. 2. This form of Safety Valve had the
important property of fitting to its bearing-seat
in all positions, requiring no other guide than
its own spherical seat to effect that essential
purpose. And as the weight required to keep the
valve closed until the exact desired maximum
pressure of steam has been attained, is directly
attached to the under side of the valve by the
rod, the weight, by being inside the boiler, is
placed out of reach from any attempt to tamper
with it. The entire arrangement of this
Safety Valve is quite simple. It is free from all
Lever Joints and other parts which might become
clogged; and as there is always a slight
pendulous motion in the weight by the action of
the water in the boiler, the spherical surfaces
of the valve and its seat are thus ever kept in
perfect order. As soon as the desired pressure of
steam has been reached, and the gravity of the
weight overcome, the valve rises from its seat,
and gives perfectly free egress to any farther
accumulation of steam. It is really quite a
treat, in its way, to observe this truly simple
and effective Safety Valve in action. After I had
contrived and introduced this Safety Valve, its
valuable properties were speedily acknowledged,
and. its employment has now become very general.
One
of the most tedious and costly processes in the
execution of the detail parts of machinery is the
cutting out of Cottar Slots in piston rods,
connecting rods, and key recesses in shafts. This
operation used to be performed by drilling a row
of holes through the solid body of the object,
and then chipping away the intermediate metal
between the holes, and filing the rude slot, so
produced, into its required form. The whole
operation, as thus conducted, was one of the most
tedious and irksome jobs that an engineer workman
could be set to, and could only be performed by
those possessed of the highest skill.
What
with broken chisels and files, and the tedious
nature of the work, it was a most severe task to
the very best men, not to speak of the heavy cost
in wages.
In
order to obviate all these disadvantages, I
contrived an arrangement of a drilling machine,
with a specially formed drill, which at once
reduced the process to one of the easiest
conducted in an engineer's workshop.
The.
"special" form of the Drill consisted
in the removal of the centre portion of its flat
cutting face by making it with a notch O. This
enabled it to cut sideways,+, as well as
downwards, and thus to cut a slit or oblong hole.
No labour, as such, was required; but only the
intelligent superintendence of a lad to place the
work in the machine, and remove it for the next
piece in its turn. The machine did the labour,
and by its self-action did the work in the most
perfect manner. I may
further mention that the arrangement of the
machine consisted in causing the object to
traverse to and fro in a straight line, of any
required length, under the action of the drill.
The traversing action was obtained by the
employment of an adjustable crank, which gave the
requisite motion to a slide table, on which the
work was fastened, The "feed" downwards
of the drill was effected by the crank at the
moment of its reversing the slide, as the drill
reached the end of the traverse; and, as there is
a slight pause of the traverse at each end of it,
the "feed" for the next cutting taking
place at that time, the drill has the opportunity
given to perfect its cut ere it commences the
next cutting traverse in succession. This action
continues in regular course until the drill makes
its way right through the piece of work under its
action; or can be arrested at any required depth
according to the requirements of the work. Soap
and water as a lubricator continues to drop into
the recess of the slot, and is always in its
right place to assist the cutting of the drill.
As
before said, the entire function of this most
effective machine tool is self-acting. It only
required an intelligent lad or labourer to attend
to it; and, as there was ample time to spare, the
superintendence of two of these machines was
quite within his ability. The rates of the
productive powers of this machine, as compared
with the former employment of hand labour, was at
least ten to one; to say nothing of the superior
quality of the work executed.
Such
were the manifold advantages of this machine,
that its merits soon became known and
appreciated; and although I had taken out no
patent for it, we always had an abundance of
orders, as it was its own best advertisement.
This
engine is of great simplicity and get-at-ability
of parts. It is specially adapted for
screw-propelled steamships, and many other
purposes. It is now in very general use. The
outline is given above.
Dr.
Faraday having applied to me to furnish him, for
one of his lectures at the Royal Institution,
with some striking example of the Power of
Machinery in overcoming the resistance to
penetration in the case of some such material as
cold malleable iron, it occurred to me to apply
the tranquil but vast power of a hydraulic press
to punch out a large hole in a thick cake of
malleable iron. Knowing that my excellent friend
John Rick had in his works at Bolton one of the
most powerful hydraulic presses then existing,
contrived and constructed by his ingenious
father, the late Benjamin Hick, I proceeded to
Bolton, and explained Dr. Faraday's requirement,
when, with his usual liberal zeal, Mr. Hick at
once placed the use of his great hydraulic press
at my service.
Having
had a suitable cake of steam-hammered malleable
iron given to me for the purpose in question, by
my valued friend Thomas Lever Rushton of the
Bolton Ironworks, we soon had the cake of iron
placed in the great press. It was 5 inches
thick,18 inches long, and 15 inches wide. Placing
a cylindrical coupling box of cast-iron on the
table of the press, and then placing the thick
cake of iron on it, and a short cylindrical mass
of iron (somewhat of the size and form of a
Stilton Cheese) on the iron cake, the coupling
box acting as the Bolster of the extemporised
punching machine, -- the press was then set to
work. We soon saw the Stilton Cheese-like punch
begin to sink slowly and quietly through the
5-inch thick cake of iron, as if it had been
stiff clay. The only sound heard was when the
punched-out mass dropped into the recess of the
coupling below. Such a demonstration of tranquil
but almost resistless power of a hydraulic press
had never, so far as we were aware, been seen
before. The punched of iron, together with the
punched-out disc, were then packed off to
Faraday; and great was his delight in having his
request so promptly complied with. Great also was
the wonder of his audience when the punched plate
was placed upon the lecture table. This feat of
Benjamin Hick's great hydraulic press set me
a-thinking. I conceived the idea that the
application of hydraulic press power might serve
many similar purposes in dealing with ultra thick
plates or bar iron, -- such as the punching out
of holes, and cutting thick bars and plates into
definite shapes, as might be required. I
suggested the subject to my friend Charles Fox,
head of the firm of Fox, Henderson, and Co. He
had taken a large contract for a chain bridge,
the links of which were to be of thick flat iron
bars, with the ends broadened out for the
link-pins to pass through. He had described to me
the trouble and cost they had occasioned him in
drilling the holes, and in cropping the
rude-shaped ends of the bars into the required
form. I advised him to try the use of the
hydraulic press as a punching-machine, and also
as a cutting-machine to dress the ends of the
great links. He did so in due time, and found the
suggestion of great service and value to him in
this, and in other cases of a similar kind. The
saving of cost was very great, and the work was
much more perfect than under the former system.
This
is so arranged that the observer can direct the
Telescope and view an object in any part of the
heavens without moving from his seat, which is
attached to the turn-table. For explanations, see
text, p. 337.
This
is a very valuable tool. It requires only one
attendant. It is especially useful as regards
efficiency and economy. It will be sufficiently
understood by mechanical engineers from the
annexed drawings.
This
Rolling Mill consists of two combined
steam-engines, acting on cranks at right angles,
the reversing of the rolls being effected by the
link motion. The requisite rolling power is
obtained by suitable wheel and pinion gear, so as
to be entirely independent of the momentum of a
fly-wheel, which is entirely dispensed with.
I
did not patent the invention. As usual in such
cases, I made no secret of it, but sent sketches
explanatory of the arrangement to many
professional friends interested in mechanical
improvements. It was adopted by many, especially
for rolling long and heavy bars and plates. It
enabled the workmen to "see-saw" these
ponderous objects, and pass them to and fro
through the rolls with the utmost case, -- to the
great saving of heat, time, and labour. The
invention was first brought into use by Mr.
Ramsbotham at the Crewe works of the London and
North-Western Railway. On the 4th December 1866 I
received the following letter from him:
"DEAR
SIR -- I must crave your forgiveness for my great
delay in acknowledging the receipt of your kind
letter of the 29th August, in which you refer to
the successful carrying out at these works of
your idea of a 'Reversible Rolling Mill without a
Fly-wheel.' It has long been to me a matter of
astonishment that your idea has not been reduced
to practice years ago, particularly when it is
considered how well the arrangement is adapted to
the rolling of Armour Plates, or other work
requiring a sustained effort, whilst it is at the
same time more effective than the ordinary mill
arrangement for very light work. So much is this
latter true, that the men who are left to their
own choice in the matter, will reverse the mill
rather than pass a light sheet of 8 or 10 lbs.
weight over the upper roll. This country is much
indebted to you for so valuable a suggestion; and
now that it has been brought to a successful
issue, I have no doubt but it will be widely
acted upon. I need not add that it will afford me
much pleasure to show you the mill, and also what
we are doing generally, if you should at any time
visit Crewe. -- Believe me very faithfully yours,
" J. RAMSBOTHAM."
I
also communicated the invention to Mr. Thomas
Gillott of the Farnley Ironworks, Yorkshire, and
received from him the following letter, dated the
2d January 1877 :
"
DEAR SIR -- I was much gratified to see by your
letter in Engineering the interest you
have shown with respect to the large Reversing
Plate Mill erected by me at these works, and
drawn on the plan suggested by you. Allow me to
thank you for the complimentary manner in which
you have mentioned my work. Since the notice
appeared, we have done a deal of heavy work in
this mill; and a plate large enough to shear 11'
0" and 10' 2" and 1/2" thick has
been rolled in five minutes. The slab went
through the roll 17 times before being rolled to
the width and turned round, and 18 times after
turning and of the full width; making a total of
35 passes -- the turning occupying 20 seconds.
When it is remembered how rapidly a thin plate
cools, this performance will sufficiently
indicate the severe work this mill is capable of
doing; notwithstanding the many predictions that
such large plates could not be rolled without a
fly-wheel. As to repairs, none have been
required; so I cannot compare this with the
Clutch systems. In respect of steam used, the
direct acting engines compare favourably with an
expansion beam condensing engine doing similar
but lighter work. Should it ever be your wish to
see this mill at work, I should be much pleased
to have the opportunity of showing it to you. --
I am, dear sir, your obedient servant,
"THOMAS
GILLOTT."
Besides
these contrivances and methods of accomplishing
mechanical objects, I have on several occasions
read papers, prepared drawings, and given
suggestions, out of which have come so-called
"inventions" made by others. For
instance, at the meeting of the British
Association in Liverpool in 1854, I read a paper
and exhibited drawings before the Mechanical
Science Section, on my method of drilling tunnels
through hard rock. The paper and drawings excited
considerable interest among the railway engineers
who were present. I afterwards met Mr. George
Newmann, C.E., who consulted me on the same
subject. Several years after (21st April 1863) I
received the following letter from him:
"DEAR
Sir -- Some few years ago, I had the pleasure of
spending an evening in your company at my
relative's (Mr. G. Withington) house at
Pendleton. As I was then Engineer to the Victor
Emmanuel Railway, and had made a survey of the
Mout Cenis for the purpose of the Tunnel, I
consulted you as to the application of the
machinery for that work. You suggested the
driving of drills in a manner similar to a
piston-rod, with other details. On my return to
Savoy, I communicated these ideas to Mr.
Bartlett, the contractor's agent, and I
recommended him to get a small trial machine
made. This he had done in a few months, and then
he claimed the whole idea as his own. The system
has since been carried out (see Times, 4th
April 1863) by compressed air instead of steam. I
call your attention to this, as you may
contradict, if you think proper, the assertion in
the article above mentioned, that the idea
originated with Bartlett."
I
did not, however, contradict the
assertion. I am glad that my description and
drawings proved in any way useful towards the
completion of that magnificent work, the
seven-mile tunnel under Mont Cenis.
In
like manner, I proposed the use of Chilled
Cast-Iron Shot at a meeting of the Mechanical
Science Section of the British Association, held
at Cambridge in October 1862. Up to that time
hardened steel shot had been used to penetrate
thick iron plates, but the cost was excessive,
about £30 a ton. I proposed that Chilled
Cast-Iron should be substituted; it was more
simple and inexpensive. Considerable discussion
took place on the subject; and Sir William
Fairbairn, who was President of the Section, said
that "he would have experiments made, and he
hoped that before the next meeting of the
Association, the matter would be proved
experimentally. A brief report of the discussion
is given in the Times of the 7th October,
and in the Athenaeum of the 18th October,
1862. Before, however, the matter could be put to
the test of experiment, Major Palliser had taken
out his Patent for the invention of Chilled
Cast-Iron Shot, in May 1863, for which he was
afterwards handsomely rewarded.
I
do not wish to "grasp" at any man's
inventions, but it is right to claim my own, and
to state the facts. The discussion above
mentioned took place upon a paper read by J.
Aston, Esq., Q.C., who thus refers to the subject
in his letter to me, dated the 7th January 1867:
"I
perfectly remember the discussion which took
place at the meeting of the British Association
at Cambridge in 1862, upon the material proper to
be used as projectiles. The discussion arose
after a paper had been read by me in the
Mechanical Section upon 'Rifled guns and
projectiles adapted for attacking armour plates.'
The paper was, I think, printed by the
Association in their Report for 1862. You spoke,
I believe, at some length on the occasion; and I
recollect that you surprised and much interested
all who were present, by strenuously urging the
use of Chilled Cast-iron for shot and shell,
intended for penetrating armour plates.
"Having
embraced all opportunities, and I had many at
that time, of ascertaining all that was done in
the way of improving rifled projectiles, I
entertained a very strong opinion that
experiments had shown that ordinary cast-iron
was, as compared with steel, of very little value
for shot and shell to be used against iron
plates. For that reason, I remember I took an
opportunity, after the termination of the
discussion, in which you held your own against
all comers in favour of chilled cast-iron, of
questioning you closely on the subject, and you
gave me, I admitted, good reason for the opinion
you expressed. You also urged me to cause a trial
to be made of chilled cast-iron for shell, such
as I had shown to the section, and which (in
hardened steel shot) had been fired by Mr.
Whitworth through thick iron plates. This I had
not an opportunity of doing. Term began soon
after, and Temple occupations then took up all my
time. "There can be no doubt whatever that
any one who may claim to have been before you in
teaching the public the use of Chilled Cast Iron
for projectiles intended to penetrate iron
plates, must give proof of having so done prior
to your vigorous advocacy of that material at the
Cambridge Meeting in 1862. -- Yours very
sincerely, "J.Aston."
In
another letter Mr. Aston says -- "It is
quite right of you to assert your claim to that
which in fact belongs to you." I did not,
however, assert my claim; and, with these
observations and extracts, I leave the matter,
stating again the fact that my public
communication of the invention was made in
October 1862; and that the patent for the
invention was taken out by Major Palliser in May
1863.
I have
only mentioned the more prominent of my
inventions and contrivances. Had I described them
fully I should have required another volume. I
have the satisfaction to know that many of them
have greatly advanced the progress of the
mechanical arts, though they may not be
acknowledged as mine. I patented very few of my
inventions. The others I sowed broadcast over the
world of practical mechanics. My reward is in the
knowledge that these "children of my
brain" are doing, and will continue to do,
good service in time present and in time to come.
In
mechanical structures and contrivances, I have
always endeavoured to attain the desired purpose
by the employment of the Fewest Parts,
casting aside every detail not absolutely
necessary, and guarding carefully against the
intrusion of mere traditional forms and
arrangements. The latter are apt t
James Nasmyth's Expansometer, 1826.