On the Economy of Machinery and Manufactures, Charles Babbage [classic romance novels .TXT] 📗
- Author: Charles Babbage
- Performer: -
Book online «On the Economy of Machinery and Manufactures, Charles Babbage [classic romance novels .TXT] 📗». Author Charles Babbage
would, however, be of little avail, unless an easy method was
contrived of producing an unlimited number of cards, each exactly
fitting the bore of the barrel. The small steel tool used for
this purpose cuts out innumerable circles similar to its cutting
end, each of which precisely fills the barrel for which it was
designed.
138. Ornaments of gilt paper. The golden stars, leaves, and
other devices, sold in shops for the purpose of ornamenting
articles made of paper and pasteboard, and other fancy works, are
cut by punches of various forms out of sheets of gilt paper.
139. Steel chains. The chain used in connecting the
mainspring and fusee in watches and clocks, is composed of small
pieces of sheet steel, and it is of great importance that each of
these pieces should be of exactly the same size. The links are of
two sorts; one of them consisting of a single oblong piece of
steel with two holes in it, and the other formed by connecting
two of the same pieces of steel, placed parallel to each other,
and at a small distance apart, by two rivets. The two kinds of
links occur alternately in the chain: each end of the single
pieces being placed between the ends of two others, and connected
with them by a rivet passing through all three. If the rivet
holes in the pieces for the double links are not precisely at
equal distances, the chain will not be straight, and will,
consequently, be unfit for its purpose.
Copying with elongation
140. In this species of copying there exists but little
resemblance between the copy and the original. It is the
cross-section only of the thing produced which is similar to the
tool through which it passes. When the substances to be operated
upon are hard, they must frequently pass in succession through
several holes, and it is in some cases necessary to anneal them
at intervals.
141. Wire drawing. The metal to be converted into wire is
made of a cylindrical form, and drawn forcibly through circular
holes in plates of steel: at each passage it becomes smaller.
and, when finished, its section at any point is a precise copy of
the last hole through which it passed. Upon the larger kinds of
wire, fine lines may sometimes be traced, running longitudinally.
these arise from slight imperfections in the holes of the
draw-plates. For many purposes of the arts, wire, the section of
which is square or half round, is required: the same method of
making it is pursued, except that the holes through which it is
drawn are in such cases themselves square, or half-round, or of
whatever other form the wire is required to be. A species of wire
is made, the section of which resembles a star with from six to
twelve rays; this is called pinion wire, and is used by the
clockmakers. They file away all the rays from a short piece,
except from about half an inch near one end: this becomes a
pinion for a clock; and the leaves or teeth are already burnished
and finished, from having passed through the draw-plate.
142. Tube drawing. The art of forming tubes of uniform
diameter is nearly similar in its mode of execution to wire
drawing. The sheet brass is bent round and soldered so as to form
a hollow cylinder; and if the diameter outside is that which is
required to be uniform, it is drawn through a succession of
holes, as in wire drawing: If the inside diameter is to be
uniform, a succession of steel cylinders, called triblets, are
drawn through the brass tube. In making tubes for telescopes, it
is necessary that both the inside and outside should be uniform.
A steel triblet, therefore, is first passed into the tube, which
is then drawn through a succession of holes, until the outside
diameter is reduced to the required size. The metal of which the
tube is formed is condensed between these holes and the steel
cylinder within; and when the latter is withdrawn the internal
surface appears polished. The brass tube is considerably extended
by this process, sometimes even to double its first length.
143. Leaden pipes. Leaden pipes for the conveyance of water
were formerly made by casting; but it has been found that they
can be made both cheaper and better by drawing them through holes
in the manner last described. A cylinder of lead, of five or six
inches in diameter and about two feet long, is cast with a small
hole through its axis, and an iron triblet of about fifteen feet
in length is forced into the hole. It is then drawn through a
series of holes, until the lead is extended upon the triblet from
one end to the other, and is of the proper thickness in
proportion to the size of the pipe.
144. Iron rolling. When cylinders of iron of greater
thickness than wire are required, they are formed by passing
wrought iron between rollers, each of which has sunk in it a
semi-cylindrical groove; and as such rollers rarely touch
accurately, a longitudinal line will usually be observed in the
cylinders so manufactured. Bar iron is thus shaped into all the
various forms of round, square, half-round, oval, etc. in which
it occurs in commerce. A particular species of moulding is thus
made, which resembles, in its section, that part of the frame of
a window which separates two adjacent panes of glass. Being much
stronger than wood, it can be considerably reduced in thickness,
and consequently offers less obstruction to the light; it is much
used for skylights.
145. It is sometimes required that the iron thus produced
should not be of uniform thickness throughout. This is the case
in bars for railroads, where greater depth is required towards
the middle of the rail which is at the greatest distance from the
supports. This form is produced by cutting the groove in the
rollers deeper at those parts where additional strength is
required, so that the hollow which surrounds the roller would, if
it could be unwound, be a mould of the shape the iron is intended
to fit.
146. Vermicelli. The various forms into which this paste is
made are given by forcing it through holes in tin plate. It
passes through them, and appears on the other side in long
strings. The cook makes use of the same method in preparing
butter and ornamental pastry for the table, and the confectioner
in forming cylindrical lozenges of various composition.
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
Comments (0)