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Manufacturing

On The Exportation Of Machinery
437. A few years only have elapsed, since our workmen were n...

Extending The Time Of Action Of Forces
45. This is one of the most common and most useful of the em...

Enquiries Previous To Commencing Any Manufactory
298. There are many enquiries which ought always to be made ...

Increase And Diminution Of Velocity
32. The fatigue produced on the muscles of the human frame d...

On A New System Of Manufacturing
305. A most erroneous and unfortunate opinion prevails among...

Distinction Between Making And Manufacturing
163. The economical principles which regulate the application...

On The Influence Of Verification On Price
181. The money price of an article at any given period is us...

Sources Of The Advantages Arising From Machinery And Manufactures
1. There exists, perhaps, no single circumstance which disti...

Of The Identity Of The Work When It Is Of The Same Kind And Its Accuracy When Of Different Kinds
79. Nothing is more remarkable, and yet less unexpected, than...

Of Copying
82. The two last-mentioned sources of excellence in the work ...

Of Copying By Punching
133. This mode of copying consists in driving a steel punch ...

On Combinations Amongst Masters Or Workmen Against Each Other
353. There exist amongst the workmen of almost all classes, ...

On The Division Of Labour
241. We have already mentioned what may, perhaps, appear par...

On Contriving Machinery
318. The power of inventing mechanical contrivances, and of ...

On The Causes And Consequences Of Large Factories
263. On examining the analysis which has been given in chapt...

On The Effect Of Taxes And Of Legal Restrictions Upon Manufactures
414. As soon as a tax is put upon any article, the ingenuity ...

Of Raw Materials
210. Although the cost of any article may be reduced in its ...

Of Printing From Cavities
83. The art of printing, in all its numerous departments, is ...

Of Money As A Medium Of Exchange
166. In the earlier stages of societies the interchange of t...

On The Future Prospects Of Manufactures As Connected With Science
453. In reviewing the various processes offered as illustrat...



Of Copying With Altered Dimensions








147. Of the pentagraph. This mode of copying is chiefly used
for drawings or maps: the instrument is simple; and, although
usually employed in reducing, is capable of enlarging the size of
the copy. An automaton figure, exhibited in London a short time
since, which drew profiles of its visitors, was regulated by a
mechanism on this principle. A small aperture in the wall,
opposite the seat in which the person is placed whose profile is
taken, conceals a camera lucida, which is placed in an adjoining
apartment: and an assistant, by moving a point, connected by a
pentagraph with the hand of the automaton, over the outline of
the head, causes the figure to trace a corresponding profile.

148. By turning. The art of turning might perhaps itself be
classed amongst the arts of copying. A steel axis, called a
mandril, having a pulley attached to the middle of it, is
supported at one end either by a conical point, or by a
cylindrical collar, and at the other end by another collar,
through which it passes. The extremity which projects beyond this
last collar is formed into a screw, by which various instruments,
called chucks, can be attached to it. These chucks are intended
to hold the various materials to be submitted to the operation of
turning, and have a great variety of forms. The mandril with the
chuck is made to revolve by a strap which passes over the pulley
that is attached to it, and likewise over a larger wheel moved
either by the foot, or by its connection with steam or water
power. All work which is executed on a mandril partakes in some
measure of the irregularities in the form of that mandril; and
the perfect circularity of section which ought to exist in every
part of the work, can only be ensured by an equal accuracy in the
mandril and its collar.

149. Rose engine turning. This elegant art depends in a great
measure on copying. Circular plates of metal called rosettes,
having various indentations on the surfaces and edges, are fixed
on the mandril, which admits of a movement either end-wise or
laterally: a fixed obstacle called the 'touch', against which the
rosettes are pressed by a spring, obliges the mandril to follow
their indentations, and thus causes the cutting tool to trace out
the same pattern on the work. The distance of the cutting tool
from the centre being usually less than the radius of the
rosette, causes the copy to be much diminished.

150. Copying dies. A lathe has been long known in France, and
recently been used at the English mint for copying dies. A blunt
point is carried by a very slow spiral movement successively over
every part of the die to be copied, and is pressed by a weight
into all the cavities; while a cutting point connected with it by
the machine traverses the face of a piece of soft steel, in which
it cuts the device of the original die on the same or on a
diminished scale. The degree of excellence of the copy increases
in proportion as it is smaller than the original. The die of a
crown-piece will furnish by copy a very tolerable die for a
sixpence. But the chief use to be expected from this lathe is to
prepare all the coarser parts, and leave only the finer and more
expressive lines for the skill and genius of the artist.

151. Shoe-last making engine. An instrument not very unlike
in principle was proposed for the purpose of making shoe lasts. A
pattern last of a shoe for the right foot was placed in one part
of the apparatus, and when the machine was moved, two pieces of
wood, placed in another part which had been previously adjusted
by screws, were cut into lasts greater or less than the original,
as was desired; and although the pattern was for the right foot,
one of the lasts was for the left, an effect which was produced
by merely interposing a wheel which reversed the motion between
the two pieces of wood to be cut into lasts.

152. Engine for copying busts. Many years since, the late Mr
Watt amused himself with constructing an engine to produce copies
of busts or statues, either of the same size as the original, or
in a diminished proportion. The substances on which he operated
were various, and some of the results were shewn to his friends,
but the mechanism by which they were made has never been
described. More recently, Mr Hawkins, who, nearly at the same
time, had also contrived a similar machine, has placed it in the
hands of an artist, who has made copies in ivory from a variety
of busts. The art of multiplying in different sizes the figures
of the sculptor, aided by that of rendering their acquisition
cheap through the art of casting, promises to give additional
value to his productions, and to diffuse more widely the pleasure
arising from their possession.

153. Screw cutting. When this operation is performed in the
lathe by means of a screw upon the mandril, it is essentially an
art of copying, but it is only the number of threads in a given
length which is copied; the form of the thread, and length as
well as the diameter of the screw to be cut, are entirely
independent of those from which the copy is made. There is
another method of cutting screws in a lathe by means of one
pattern screw, which, being connected by wheels with the mandril,
guides the cutting point. In this process, unless the time of
revolution of the mandril is the same as that of the screw which
guides the cutting point, the number of threads in a given length
will be different. If the mandril move quicker than the cutting
point, the screw which is produced will be finer than the
original; if it move slower, the copy will be more coarse than
the original. The screw thus generated may be finer or coarser--
it may be larger or smaller in diameter--it may have the same or
a greater number of threads than that from which it is copied;
yet all the defects which exist in the original will be
accurately transmitted, under the modified circumstances, to
every individual generated from it.

154. Printing from copper plates with altered dimensions.
Some very singular specimens of an art of copying, not yet made
public, were brought from Paris a few years since. A watchmaker
in that city, of the name of Gonord, had contrived a method by
which he could take from the same copperplate impressions of
different sizes, either larger or smaller than the original
design. Having procured four impressions of a parrot, surrounded
by a circle, executed in this manner, I shewed them to the late
Mr Lowry, an engraver equally distinguished for his skill, and
for the many mechanical contrivances with which he enriched his
art. The relative dimensions of the several impressions were 5.5,
6.3, 8.4, 15.0, so that the largest was nearly three times the
linear size of the smallest; and Mr Lowry assured me, that he was
unable to detect any lines in one which had not corresponding
lines in the others. There appeared to be a difference in the
quantity of ink, but none in the traces of the engraving; and,
from the general appearance, it was conjectured that the largest
but one was the original impression from the copperplate.

The means by which this singular operation was executed have
not been published; but two conjectures were formed at the time
which merit notice. It was supposed that the artist was in
possession of some method of transferring the ink from the lines
of a copperplate to the surface of some fluid, and of
retransferring the impression from the fluid to paper. If this
could be accomplished, the print would, in the first instance, be
of exactly the same size as the copper from which it was derived;
but if the fluid were contained in a vessel having the form of an
inverted cone, with a small aperture at the bottom, the liquid
might be lowered or raised in the vessel by gradual abstraction
or addition through the apex of the cone; in this case, the
surface to which the printing-ink adhered would diminish or
enlarge, and in this altered state the impression might be
retransferred to paper. It must be admitted, that this
conjectural explanation is liable to very considerable
difficulties; for, although the converse operation of taking an
impression from a liquid surface has a parallel in the art of
marbling paper, the possibility of transferring the ink from the
copper to the fluid requires to be proved.

Another and more plausible explanation is founded on the
elastic nature of the compound of glue and treacle, a substance
already in use in transferring engravings to earthenware. It is
conjectured, that an impression from the copperplate is taken
upon a large sheet of this composition; that this sheet is then
stretched in both directions, and that the ink thus expanded is
transferred to paper. If the copy is required to be smaller than
the original, the elastic substance must first be stretched, and
then receive the impression from the copperplate: on removing the
tension it will contract, and thus reduce the size of the design.
It is possible that one transfer may not in all cases suffice; as
the extensibility of the composition of glue and treacle,
although considerable, is still limited. Perhaps sheets of India
rubber of uniform texture and thickness, may be found to answer
better than this composition; or possibly the ink might be
transferred from the copper plate to the surface of a bottle of
this gum, which bottle might, after being expanded by forcing air
into it, give up the enlarged impression to paper. As it would
require considerable time to produce impressions in this manner,
and there might arise some difficulty in making them all of
precisely the same size, the process might be rendered more
certain and expeditious by performing that part of the operation
which depends on the enlargement or diminution of the design only
once; and, instead of printing from the soft substance.
transferring the design from it to stone: thus a considerable
portion of the work would be reduced to an art already well
known, that of lithography. This idea receives some confirmation
from the fact, that in another set of specimens, consisting of a
map of St Petersburgh, of several sizes, a very short line,
evidently an accidental defect, occurs in all the impressions of
one particular size, but not in any of a different size.

155. Machine to produce engraving from medals. An instrument
was contrived, a long time ago, and is described in the Manuel de
Tourneur, by which copperplate engravings are produced from
medals and other objects in relief. The medal and the copper are
fixed on two sliding plates at right angles to each other, so
connected that, when the plate on which the medal is fixed is
raised vertically by a screw, the slide holding the copperplate
is advanced by an equal quantity in the horizontal direction. The
medal is fixed on the vertical slide with its face towards the
copperplate, and a little above it.

A bar, terminating at one end in a tracing point, and at the
other in a short arm, at right angles to the bar, and holding a
diamond point, is placed horizontally above the copper; so that
the tracing point shall touch the medal to which the bar is
perpendicular, and the diamond point shall touch the copperplate
to which the arm is perpendicular.

Under this arrangement, the bar being supposed to move
parallel to itself, and consequently to the copper, if the
tracing point pass over a flat part of the medal, the diamond
point will draw a straight line of equal length upon the copper;
but, if the tracing point pass over any projecting part of the
medal, the deviation from the straight line by the diamond point,
will be exactly equal to the elevation of the corresponding point
of the medal above the rest of the surface. Thus, by the transit
of this tracing point over any line upon the medal, the diamond
will draw upon the copper a section of the medal through that
line.

A screw is attached to the apparatus, so that if the medal be
raised a very small quantity by the screw, the copperplate will
be advanced by the same quantity, and thus a new line of section
may be drawn: and, by continuing this process, the series of
sectional lines on the copper produces the representation of the
medal on a plane: the outline and the form of the figure arising
from the sinuosities of the lines, and from their greater or less
proximity. The effect of this kind of engraving is very striking;
and in some specimens gives a high degree of apparent relief. It
has been practised on plate glass, and is then additionally
curious from the circumstance of the fine lines traced by the
diamond being invisible, except in certain lights.

From this description, it will have been seen that the
engraving on copper must be distorted; that is to say, that the
projection on the copper cannot be the same as that which arises
from a perpendicular projection of each point of the medal upon a
plane parallel to itself. The position of the prominent parts
will be more altered than that of the less elevated; and the
greater the relief of the medal the more distorted will be its
engraved representation. Mr John Bate, son of Mr Bate, of the
Poultry, has contrived an improved machine, for which he has
taken a patent, in which this source of distortion is remedied.
The head, in the title page of the present volume, is copied from
a medal of Roger Bacon, which forms one of a series of medals of
eminent men, struck at the Royal Mint at Munich, and is the first
of the published productions of this new art.(3*)

The inconvenience which arises from too high a relief in the
medal, or in the bust, might be remedied by some mechanical
contrivance, by which the deviation of the diamond point from the
right line (which it would describe when the tracing point
traverses a plane), would be made proportional not to the
elevation of the corresponding point above the plane of the
medal, but to its elevation above some other parallel plane
removed to a fit distance behind it. Thus busts and statues might
be reduced to any required degree of relief.

156. The machine just described naturally suggests other
views which seem to deserve some consideration, and, perhaps,
some experiment. If a medal were placed under the tracing point
of a pentagraph, an engraving tool substituted for the pencil,
and a copperplate in the place of the paper; and if, by some
mechanism, the tracing point, which slides in a vertical plane,
could, as it is carried over the different elevations of the
medal, increase or diminish the depth of the engraved line
proportionally to the actual height of the corresponding point on
the medal, then an engraving would be produced, free at least
from any distortion, although it might be liable to objections of
a different kind. If, by any similar contrivance, instead of
lines, we could make on each point of the copper a dot, varying
in size or depth with the altitude of the corresponding point of
the medal above its plane, than a new species of engraving would
be produced: and the variety of these might again be increased,
by causing the graving point to describe very small circles, of
diameters, varying with the height of the point on the medal
above a given plane; or by making the graving tool consist of
three equidistant points, whose distance increased or diminished
according to some determinate law, dependent on the elevation of
the point represented above the plane of the medal. It would,
perhaps, be difficult to imagine the effects of some of these
kinds of engraving; but they would all possess, in common, the
property of being projections, by parallel lines, of the objects
represented, and the intensity of the shade of the ink would
either vary according to some function of the distance of the
point represented from some given plane, or it would be a little
modified by the distances from the same plane of a few of the
immediately contiguous points.

157. The system of shading maps by means of lines of equal
altitude above the sea bears some analogy to this mode of
representing medals, and if applied to them would produce a
different species of engraved resemblance. The projections on the
plane of the medal, of the section of an imaginary plane, placed
at successive distances above it, with the medal itself, would
produce a likeness of the figure on the medal, in which all the
inclined parts of it would be dark in proportion to their
inclination. Other species of engraving might be conceived by
substituting, instead of the imaginary plane, an imaginary sphere
or other solid, intersecting the figure in the medal.

158. Lace made by caterpillars. A most extraordinary species
of manufacture, which is in a slight degree connected with
copying, has been contrived by an officer of engineers residing
at Munich. It consists of lace, and veils, with open patterns in
them, made entirely by caterpillars. The following is the mode of
proceeding adopted: he makes a paste of the leaves of the plant,
which is the usual food of the species of caterpillar(4*) he
employs, and spreads it thinly over a stone, or other flat
substance. He then, with a camel-hair pencil dipped in olive oil,
draws upon the coating of paste the pattern he wishes the insects
to leave open. This stone is then placed in an inclined position,
and a number of the caterpillars are placed at the bottom. A
peculiar species is chosen, which spins a strong web; and the
animals commencing at the bottom, eat and spin their way up to
the top, carefully avoiding every part touched by the oil, but
devouring all the rest of the paste. The extreme lightness of
these veils, combined with some strength, is truly surprising.
One of them, measuring twenty-six and a half inches by seventeen
inches, weighed only 1.51 grains; a degree of lightness which
will appear more strongly by contrast with other fabrics. One
square yard of the substance of which these veils are made weighs
4 1/3 grains, whilst one square yard of silk gauze weighs 137
grains, and one square yard of the finest patent net weighs 262
1/2 grains. The ladies' coloured muslin dresses, mentioned in the
table subjoined, cost ten shillings per dress, and each weigh six
ounces; the cotton from which they are made weighing nearly six
and two-ninth ounces avoirdupois weight.

Weight of one square yard of each of the following articles(5*)

Weight of
Weight cotton used
Value finished of in waking
per yard one square one square
Description of goods measure yard yard

s. d. Troy grains Troy grains

Caterpillar veils -- 4 1/3 --
Silk gauze 3-4 wide 1 0 137 --
Finest patent net -- 262 1/2 --
Fine cambric muslin -- 551 --
6-4ths jaconet muslin 2 0 613 670
Ladies' coloured muslin dresses 3 0 788 875
6-4ths cambric 1 2 972 1069
9-8ths calico 0 9 988 1085
1/2-yard nankeen 0 8 2240 2432


159. This enumeration, which is far from complete, of the
arts in which copying is the foundation, may be terminated with
an example which has long been under the eye of the reader;
although few, perhaps, are aware of the number of repeated
copyings of which these very pages are the subject.

1. They are copies, by printing, from stereotype plates.

2. These stereotype plates are copied, by the art of casting,
from moulds formed of plaster of Paris.

3. These moulds are themselves copied by casting the plaster
in a liquid state upon the moveable types set up by the
compositor.

[It is here that the union of the intellectual and the
mechanical departments takes place. The mysteries, however, of an
author's copying, form no part of our enquiry, although it may be
fairly remarked, that, in numerous instances, the mental far
eclipses the mechanical copyist.]

4. These moveable types, the obedient messengers of the most
opposite thoughts, the most conflicting theories, are themselves
copies by casting from moulds of copper called matrices.

5. The lower part of those matrices, bearing the impressions
of the letters or characters, are copies, by punching, from steel
punches on which the same characters exist in relief.

6. These steel punches are not themselves entirely exempted
from the great principle of art. Many of the cavities which exist
in them, such as those in the middle of the punches for the
letters a, b, d, e, g, etc., are produced from other steel
punches in which these parts are in relief.

We have thus traced through six successive stages of copying
the mechanical art of printing from stereotype plates: the
principle of copying contributing in this, as in every other
department of manufacture, to the uniformity and the cheapness of
the work produced.

NOTES:

1. The late Mr Lowry.

2. I posses a lithographic reprint of a page of a table, which
appears, from the from of the type, to have been several years
old.

3. The construction of the engraving becomes evident on examining
it with a lens of sufficient power to show the continuity of the
lines.

4. The Phalaena pardilla, which feeds on the Prunus padus.

5. Some of these weights and measures are calculated from a
statement in the Report of the Committee of the House of Commons
on Printed Cotton Goods; and the widths of the pieces there given
are presumed to be the real widths, not those by which they are
called in the retail shops.





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