elet. These sands, silicates, chalks, and
carbonates--rough contributions from Oken's 'silent realm of the
minerals'--are first crushed and mingled together by machines--one of
the best of them, I was glad to hear, of American invention--then passed
on into the great rectangular hall, in which they are shot into the
crucibles of the melting furnaces and fused, mainly by gas, on a system
invented and perfected by the late Dr. Siemens, I believe, who made such
a stir a decade ago at Glasgow by his discourse on the storage of force
before the British Association. The furnaces which, according to their
varying capacity, now require from eight to ten tons of coal a day,
consumed, before the development of the Siemens system, from sixteen to
twenty tons. Twenty-four hours now suffice for the fusion and the
casting of the glass, and if the casting were now to be conducted as
ceremoniously as in the time of that fine old martinet M. Deslandes, M.
Henrivaux would pass his life in a cocked hat, knee-breeches, peruke,
embroidered coat, and sword, for the casting now takes place every day
and at a fixed hour. None the less, rather the more, it is a work still
of extreme nicety, one to be done by experts, who must be as cool as
soldiers under fire. In a certain way and measure it is like ladling out
the molten lava of Vesuvius and pressing it into slabs for a lady's
toilette-table. The plates, once cast, must be smoothed and made even.
This is a very pretty process, and used to be performed by machines
which bore the very pretty names of _valseuses_. That paviour's rammers
should be called _demoiselles_ has always seemed to me an outrage and an
impertinence, though I may suppose it finds its excuse in the
short-waisted costumes of our grandmothers. But the movement of the
glass-smoothing _valseuses_ was really a sort of waltz movement. The
plates of glass were fixed with plaster on a solid rectangular table.
Granite-dust was scattered upon the plates, and then a wooden plateau,
armed on the under side with bands of cast iron or steel, was set to
waltzing over it backwards and forwards with a semi-rotatory motion, the
granite-dust supplied becoming finer and finer as the waltzing went on.

Instead of these _valseuses_ two great plates of glass are now fixed
side by side with plaster on huge tables, and two large ashlars are set
turning by steam on their own axes while they describe a great orbit
over the plates of glass. A stream of w