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Manufacturing

On The Effect Of Machinery In Reducing The Demand For Labour
404. One of the objections most frequently urged against mac...

On The Method Of Observing Manufacturies
160. Having now reviewed the mechanical principles which reg...

On The Division Of Labour
217. Perhaps the most important principle on which the econo...

Saving Time In Natural Operations
47. The process of tanning will furnish us with a striking i...

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

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

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

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

On The Position Of Large Factories
277. It is found in every country, that the situation of lar...

On The Duration Of Machinery
340. The time during which a machine will continue to perform...

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

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

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

Proper Circumstances For The Application Of Machinery
329. The first object of machinery, the chief cause of its e...

Of Price As Measured By Money
201. The money price at which an article sells furnishes us ...

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

On Over Manufacturing
284. One of the natural and almost inevitable consequences of...

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

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

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



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
the perfect identity of things manufactured by the same tool. If
the top of a circular box is to be made to fit over the lower
part, it may be done in the lathe by gradually advancing the tool
of the sliding-rest; the proper degree of tightness between the
box and its lid being found by trial. After this adjustment, if a
thousand boxes are made, no additional care is required; the tool
is always carried up to the stop, and each box will be equally
adapted to every lid. The same identity pervades all the arts of
printing; the impressions from the same block, or the same
copperplate, have a similarity which no labour could produce by
hand. The minutest traces are transferred to all the impressions,
and no omission can arise from the inattention or unskilfulness
of the operator. The steel punch, with which the cardwadding for
a fowling-piece is cut, if it once perform its office with
accuracy, constantly reproduces the same exact circle.

80. The accuracy with which machinery executes its work is,
perhaps, one of its most important advantages: it may, however,
be contended, that a considerable portion of this advantage may
be resolved into saving of time; for it generally happens, that
any improvement in tools increases the quantity of work done in a
given time. Without tools, that is, by the mere efforts of the
human hand, there are, undoubtedly, multitudes of things which it
would be impossible to make. Add to the human hand the rudest
cutting instrument, and its powers are enlarged: the fabrication
of many things then becomes easy, and that of others possible
with great labour. Add the saw to the knife or the hatchet, and
other works become possible, and a new course of difficult
operations is brought into view, whilst many of the former are
rendered easy. This observation is applicable even to the most
perfect tools or machines. It would be possible for a very
skilful workman, with files and polishing substances, to form a
cylinder out of a piece of steel; but the time which this would
require would be so considerable, and the number of failures
would probably be so great, that for all practical purposes such
a mode of producing a steel cylinder might be said to be
impossible. The same process by the aid of the lathe and the
sliding-rest is the everyday employment of hundreds of workmen.

81. Of all the operations of mechanical art, that of turning
is the most perfect. If two surfaces are worked against each
other, whatever may have been their figure at the commencement,
there exists a tendency in them both to become portions of
spheres. Either of them may become convex, and the other concave,
with various degrees of curvature. A plane surface is the line of
separation between convexity and concavity, and is most difficult
to hit; it is more easy to make a good circle than to produce a
straight line. A similar difficulty takes place in figuring
specula for telescopes; the parabola is the surface which
separates the hyperbolic from the elliptic figure, and is the
most difficult to form. If a spindle, not cylindrical at its end,
be pressed into a hole not circular, and kept constantly turning,
there is a tendency in these two bodies so situated to become
conical, or to have circular sections. If a triangular-pointed
piece of iron be worked round in a circular hole the edges will
gradually wear, and it will become conical. These facts, if
they do not explain, at least illustrate the principles on
which the excellence of work formed in the lathe depends.





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Previous: Economy Of The Materials Employed



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