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Updated: May 14, 2025
The rock was singularly striated, the scratches arranged concentrically and in helicoidal curves.
The extremity of the axles forms a nut into which pass vertical screws, c c. These latter are connected above with cone-wheels, l l, which, gearing with bevel wheels keyed to the shafts, e, secure a complete interdependence of the whole. The ascending motion, which is controlled by the endless screws, f, and the helicoidal wheels, m, is in this way effected with great regularity.
At the upper part, a frame, B B, formed of double T-irons cross-braced here and there, supports a transmission composed of gearwheels, R R, and a pitch-chain, G G. Along the columns of the frame, which serve as guides, move two kinds of pulley-carriers, C C. The pulleys, D D, are channeled, and receive the cable, a a, which serves as a helicoidal saw.
P. Gray has, however, devised a new process, which is based upon the theoretical considerations given above. His helicoidal saw is, in reality, an endless cable formed by twisting together three steel wires in such a way as to give the spirals quite an elongated pitch.
As early as the Seventeenth Century the possibility of developing a propulsive thrust by the use of a submerged helicoidal, or screw, propeller, had been vaguely recognized, and during the following, or Eighteenth Century, the same idea had been brought forward. It had been viewed in this connection, however, merely as a curiosity, and led to no immediate results.
The extremity, v, of the axle of the pulley to the right is threaded, and actuates a helicoidal wheel, E, which transmits motion to the wheel, R, through the intermedium of the vertical shaft, F. This transmission, completed by the wheels, R R, and the pitch-chains, G G, is designed to move the saw vertically, through the simultaneous shifting of the carriages, C C. A tension weight, P, through the intermedium of pulleys, D D , permits of keeping the saw taut.
When a magnetic field acts on the cathode particle, the latter follows a trajectory, generally helicoidal, which is anticipated by the theory. We here have to do with a question of ballistics, and experiments duly confirm the anticipations of the calculation.
Uprights, a a, of double T-iron, fixed to joists, k k, and connected and braced by pieces, d d, form a strong frame. The power necessary to run this kind of saw is less than n × ¼ H.P., on account of the number of passive parts. The most interesting application of the helicoidal saw is in the exploitation of quarries. Gay's method. Tubular Perforators. Mr.
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