Nikola Tesla Books
THE CONSTRUCTION OF LARGE APPARATUS 197 test for accuracy in running and, if the final cut on the fibre hub has been carefully taken and all burrs removed from the edge of the openings, the disc cannot run other than true. The reader's attention is next called to the housing which consists essentially of a box of suitable size built up from 7/8-inch whitewood and lined throughout with sheet asbestos. A hole is drilled in the rear of the box to admit the boss of the rotor. The box is assembled with screws throughout and the top piece, D, Fig. 9, is made removable in order to afford access to the interior of the case. The front of the box carries the stationary electrodes of the gap and the construction of these demands our attention next. The stationary electrodes consist of a pair of the 34-inch nickel steel cylinders mounted upon threaded -inch brass rods supported in brass bushings which are threaded into the wooden front of the case. A 3-inch disc of fibre on the end of each of the threaded rods provides an adjusting handle by means of which the clearance between the studs on the rotor and the stationary electrodes can be closely regulated. A strip of heavy copper ribbon establishes connection between each stationary electrode and a binding post placed a few inches beneath it. The gap may now be assembled according to Fig. 9 which shows the relative positions of the various parts so clearly that further description is unnecessary. The motor may be of the ordinary fan motor type of H.P. or even less and its speed should be about 1800 revolutions per minute. The method of mounting the motor is, of course, dependent upon the nature of the base or bed plate. The builder's ingenuity will doubtless suggest the best form of mounting to meet his individual requirements. Care should be taken to see that there is practically no
