Nikola Tesla Patents
currents are conveyed to the device. The tubular space between the plugs is partially filled with a conducting sensitive powder, as indicated, the proper amount of the same and the size of its grains being xxx determined and adjusted before hand by experiment. This tube I rotate by clockwork or other means at a uniform and suitable rate of speed, and under these. conditions I find that this device behaves towards disturbances of the kind before assumed in a manner similar to that of a stationary cell of selenium towards rays of light; its electrical resistance is diminished when it is acted upon by the disturbances, and is automatically restored upon the cessation of their influence. It is of advantage to employ round grains of powder in the tube, and in any event it is important that they should be of as uniform size and shape as possible and that provision should be made for maintaining an unchanging and very dry atmosphere in the tube. To the terminals T and T' of the condenser C¹ is connected a coil p, usually consisting of a few turns of a conductor of very small resistance - which is the primary of the transformer before referred to -in series with a dethe vice d which effects the discharge of condenser through the coil p at predetermined intervals of time. In the present case this device consists of a cylinder made partly of conducting and partly of insulating material, e and e' respectively, which is rotated at the desired rate of speed by any suitable means. The conducting part e is in good electrical connection with shaft S, and is provided with tapering segments as f upon which slides a brush k which should preferably be capable of longitudinal adjustment along the cylinder. Another brush b; which is connected to the condens15 This page retyped from microfilm for better readability - Ed.] 425
