On the Economy of Machinery and Manufactures | Page 9

to which such a mode of communication can be extended,
does not appear to have been ascertained, and would be an interesting
subject for enquiry. Admitting it to be possible between London and
Liverpool, about seventeen minutes would elapse before the words
spoken at one end would reach the other extremity of the pipe.
8. The art of using the diamond for cutting glass has undergone, within
a few years, a very important improvement. A glazier's apprentice,
when using a diamond set in a conical ferrule, as was always the
practice about twenty years since, found great difficulty in acquiring
the art of using it with certainty; and, at the end of a seven years'
apprenticeship, many were found but indifferently skilled in its
employment. This arose from the difficulty of finding the precise angle
at which the diamond cuts, and of guiding it along the glass at the

proper inclination when that angle is found. Almost the whole of the
time consumed and of the glass destroyed in acquiring the art of cutting
glass, may now be saved by the use of an improved tool. The gem is set
in a small piece of squared brass with its edges nearly parallel to one
side of the square. A person skilled in its use now files away the brass
on one side until, by trial, he finds that the diamond will make a clean
cut, when guided by keeping this edge pressed against a ruler. The
diamond and its mounting are now attached to a stick like a pencil, by
means of a swivel allowing a small angular motion. Thus, even the
beginner at once applies the cutting edge at the proper angle, by
pressing the side of the brass against a ruler; and even though the part
he holds in his hand should deviate a little from the required angle, it
communicates no irregularity to the position of the diamond, which
rarely fails to do its office when thus employed.
The relative hardness of the diamond, in different directions, is a
singular fact. An experienced workman, on whose judgement I can rely,
informed me that he has seen a diamond ground with diamond powder
on a cast-iron mill for three hours without its being at all worn, but that,
on changing its direction with respect to the grinding surface, the same
edge was ground away.
9. Employment of materials of little value. The skins used by the
goldbeater are produced from the offal of animals. The hoofs of horses
and cattle, and other horny refuse, are employed in the production of
the prussiate of potash, that beautiful, yellow, crystallized salt, which is
exhibited in the shops of some of our chemists. The worn-out
saucepans and tinware of our kitchens, when beyond the reach of the
tinker's art, are not utterly worthless. We sometimes meet carts loaded
with old tin kettles and worn-out iron coal-skuttles traversing our
streets. These have not yet completed their useful course; the less
corroded parts are cut into strips, punched with small holes, and
varnished with a coarse black varnish for the use of the trunk-maker,
who protects the edges and angles of his boxes with them; the
remainder are conveyed to the manufacturing chemists in the outskirts
of the town, who employ them in combination with pyroligneous acid,
in making a black die for the use of calico printers.

10. Of tools. The difference between a tool and a machine is not
capable of very precise distinction; nor is it necessary, in a popular
explanation of those terms, to limit very strictly their acceptation. A
tool is usually more simple than a machine; it is generally used with the
hand, whilst a machine is frequently moved by animal or steam power.
The simpler machines are often merely one or more tools placed in a
frame, and acted on by a moving power. In pointing out the advantages
of tools, we shall commence with some of the simplest.
11. To arrange twenty thousand needles thrown promiscuously into a
box, mixed and entangled in every possible direction, in such a form
that they shall be all parallel to each other, would, at first sight, appear
a most tedious occupation; in fact, if each needle were to be separated
individually, many hours must be consumed in the process. Yet this is
an operation which must be performed many times in the manufacture
of needles; and it is accomplished in a few minutes by a very simple
tool; nothing more being requisite than a small flat tray of sheet iron,
slightly concave at the bottom. In this the needles are placed, and
shaken in a peculiar manner, by throwing them up a very little, and
giving at the same time a slight longitudinal motion to the tray. The
shape of