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Page 7
In sawing hard stones, it is necessary, as well known, to keep up a
flow of water and fine sand upon the blade in order to increase its
friction. Upon two platforms, _b_, at the extremities of the machine,
are fixed the water reservoir, C, and the receptacles, C', containing
fine sand or dry pulverized grit stone. As may be seen from Figs. 5
and 6, the bottom of the sand box, C', is conical and terminates in a
hopper, T, beneath which is adjusted a slide valve, _t_, connected
with a screw that carries a pulley, T'. By means of this valve, the
bottom of the hopper may be opened or closed in such a way as to
regulate the flow of the sand at will by acting upon the pulley, T',
through a chain, _t'_, passing over the guide pulley, _t�_. A rubber
tube, _u_, which starts from the hopper, runs into a metal pipe, U,
that descends to the guide, H, with which it is connected by a collar.
Under the latter, this pipe terminates in a sphere containing a small
aperture to allow the sand to escape upon an inclined board provided
with a flange. At the same time, through the rubber tube, _c_, coming
from the reservoir, C, a stream of water is directed upon the board in
order to wet the sand.
As the apparatus with but a single endless saw makes but two kerfs at
once, Mr. Auguste has devised an arrangement by means of which several
blades may be used, and the work thus be expedited.
Without changing the general arrangements, he replaces the pulleys, P
and P', by two half drums, V and V' (Figs. 8, 9, and 10), which are
each cast in a piece with the crosspieces, D� and D�, designed to
replace D and D', and, like them, sliding up and down the columns, A,
of the frame. Motion is transmitted to all the saw blades by a cog
wheel, X, keyed to the vertical shaft, _f_, and gearing with small
pinions, _x_, which are equally distant all around, and which
themselves gear with similar pinions forming the radii of a succession
of circles concentric with the first. All these pinions are mounted
upon axles traversing bronze bearings within the drum, which, to this
effect, is provided with slots. The axles of the pinions are prolonged
in order to receive rollers, _x'_, surrounded with rubber so as to
facilitate, through friction, the motion of all the blades running
between them.
The other drum, V', is arranged in the same way, except that it is not
cast in a piece with the carriage, D�, but is so adjusted to it that
a tension may be exerted upon the blades by means of the screw, _d_,
and its hand wheel.
Through this combination, all the blades are carried along at once in
opposite directions and at the same speed.--_Publication
Industrielle._
* * * * *
ROBURITE, THE NEW EXPLOSIVE.
A series of experiments of great interest and vital importance to
colliery owners and all those engaged in mining coal has been carried
out during the last ten days in the South Yorkshire coal field. The
new mines regulation act provides that any explosible used in coal
mines shall either be fired in a water cartridge or be of such a
nature that it cannot inflame firedamp. This indeed is the problem
which has puzzled many able chemists during the last few years, and
which Dr. Roth, of Berlin, claims to have solved with his explosive
"roburite." We recently gave a detailed account of trials carried out
at the School of Military Engineering, Chatham, to test the safety and
strength of roburite, as compared with gun cotton, dynamite, and
blasting gelatine. The results were conclusive of the great power of
the new explosive, and so far fully confirmed the reports of the able
mining engineer and the chemical experts who had been sent to Germany
to make full inquiries. These gentlemen had ample opportunity of
seeing roburite used in the coal mines of Westphalia, and it was
mainly upon their testimony that the patents for the British empire
were acquired by the Roburite Explosive Company.
It has, however, been deemed advisable to give practical proof to
those who would have to use it, that roburite possesses all the high
qualities claimed for it, and hence separate and independent trials
have been arranged in such representative collieries as the
Wharncliffe Silkstone, near Sheffield, Monk Bretton, near Barnsley,
and, further north, in the Durham coal field, at Lord Londonderry's
Seaham and Silksworth collieries. Mr. G.B. Walker, resident manager of
the Wharncliffe Colliery Company, had gone to Germany as an
independent observer--provided with a letter of introduction from the
Under Secretary of State for Foreign Affairs--and had seen the
director of the government mines at Saarbruck, who gave it as his
opinion that, so far as his experience had gone, the new explosive was
a most valuable invention. Mr. Walker was so impressed with the great
advantages of roburite that he desired to introduce it into his own
colliery, where he gladly arranged with the company to make the first
coal mining experiments in this country. These were recently carried
out in the Parkgate seam of the Wharncliffe Silkstone colliery, under
the personal superintendence of the inventor, Dr. Roth, and in the
presence of a number of colliery managers and other practical men.
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