On the Economy of Machinery and Manufactures - Charles Babbage (interesting books to read in english .TXT) 📗
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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.
On the Method of Observing Manufacturies
160. Having now reviewed the mechanical principles which
regulate the successful application of mechanical science to
great establishments for the production of manufactured goods, it
remains for us to suggest a few enquiries, and to offer a few
observations, to those whom an enlightened curiosity may lead to
examine the factories of this or of other countries.
The remark—that it is important to commit to writing all
information as soon as possible after it is received, especially
when numbers are concerned—applies to almost all enquiries. It
is frequently impossible to do this at the time of visiting an
establishment, although not the slightest jealousy may exist; the
mere act of writing information as it is communicated orally, is
a great interruption to the examination of machinery. In such
cases, therefore, it is advisable to have prepared beforehand the
questions to be asked, and to leave blanks for the answers, which
may be quickly inserted, as, in a multitude of cases, they are
merely numbers. Those who have not tried this plan will be
surprised at the quantity of information which may, through its
means, be acquired, even by a short examination. Each manufacture
requires its own list of questions, which will be better drawn up
after the first visit. The following outline, which is very
generally applicable, may suffice for an illustration; and to
save time, it may be convenient to have it printed; and to bind
up, in the form of a pocket-book, a hundred copies of the
skeleton forms for processes, with about twenty of the general
enquiries.
GENERAL ENQUIRIES
Outlines of a description of any of the mechanical arts ought to
contain information on the following points
Brief sketch of its history, particularly the date of its
invention, and of its introduction into England.
Short reference to the previous states through which the
material employed has passed: the places whence it is procured:
the price of a given quantity.
[The various processes must now be described successively
according to the plan which will be given in (161); after which
the following information should be given.]
Are various kinds of the same article made in one establishment,
or at different ones, and are there differences in the processes?
To what defects are the goods liable?
What substitutes or adulterations are used?
What waste is allowed by the master?
What tests are there of the goodness of the manufactured
articles?
The weight of a given quantity, or number, and a comparison
with that of the raw material?
The wholesale price at the manufactory? (L s. d.) per ( )
The usual retail price? (L s. d.)
Who provide tools? Master, or men? Who repair tools? Master,
or men?
What is the expense of the machinery?
What is the annual wear and tear, and what its duration?
Is there any particular trade for making it? Where?
Is it made and repaired at the manufactory?
In any manufactory visited, state the number ( ) of
processes; and of the persons employed in each process; and the
quantity of manufactured produce.
What quantity is made annually in Great Britain?
Is the capital invested in manufactories large or small?
Mention the principal seats of this manufacture in England;
and if it flourishes abroad, the places where it is established.
The duty, excise. or bounty, if any, should be stated, and
any alterations in past years; and also the amount exported or
imported for a series of years.
Whether the same article, but of superior, equal, or inferior
make, is imported?
Does the manufacturer export, or sell, to a middleman, who
supplies the merchant?
To what countries is it chiefly sent? and in what goods are
the returns made?
161. Each process requires a separate skeleton, and the
following outline will be sufficient for many different
manufactories:
Process ( ) Manufacture ( )
Place ( ) Name ( )
date 183
The mode of executing it, with sketches of the tools or
machine if necessary.
The number of persons necessary to attend the machine. Are
the operatives men. ( ) women, ( ) or children? ( ) If mixed,
what are the proportions?
What is the pay of each? (s. d.) (s. d. ) (s. d.) per ( )
What number ( ) of hours do they work per day?
Is it usual, or necessary, to work night and day without
stopping? Is the labour performed by piece—or by day-work?
Who provide tools? Master, or men? Who repair tools? Master,
or men? What degree of skill is required, and how many years’ ( )
apprenticeship?
The number of times ( ) the operation is repeated per day or
per hour?
The number of failures ( ) in a thousand?
Whether the workmen or the master loses by the broken or
damaged articles?
What is done with them?
If the same process is repeated several times, state the
diminution or increase of measure, and the loss, if any, at each
repetition.
162. In this skeleton, the answers to the questions are in
some cases printed, as “Who repair the tools?—Masters, Men”; in
order that the proper answer may be underlined with a pencil. In
filling up the answers which require numbers, some care should be
taken: for instance, if the observer stands with his watch in his
hand before a person heading a pin, the workman will almost
certainly increase his speed, and the estimate will be too large.
A much better average will result from enquiring what quantity is
considered a fair day’s work. When this cannot be ascertained,
the number of operations performed in a given time may frequently
be counted when the workman is quite unconscious that any person
is observing him. Thus the sound made by the motion of a loom may
enable the observer to count the number of strokes per minute,
even though he is outside the building in which it is contained.
M. Coulomb, who had great experience in making such observations,
cautions those who may repeat his experiments against being
deceived by such circumstances: ‘Je prie’ (says he) ‘ceux qui
voudront les repeter, s’ils n’ont pas le temps de mesurer les
resultats apres plusiers jours d’un travail continu, d’observer
les ouvriers a differentes reprises dans la journee, sans qu’ils
sachent qu’ils sont observes. L’on ne peut trop avertir combien
l’on risque de se tromper en calculant, soit la vitesse, soit le
temps effectif du travail, d’apres une observation de quelques
minutes.’ Memoires de l’Institut. vol. II, p. 247.
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