High Frequency Apparatus Page 178

178 HIGH FREQUENCY APPARATUS muscular contractive effects upon the body would be lessened to a considerable degree. The commercial alternating lighting current which has a frequency of 60 or perhaps 125 cycles per second, is fatal to a human being if applied in sufficient quantities. Available data discloses that voltages of from 200 to 500 are dangerous and in some cases fatal where the frequency is of the commercial order. If, however, the frequency is increased to 10,000 cycles and upward per second, it has been found that several thousand volts may be taken through the body with comparatively little discomfort. A further increase to 100,000 cycles and over renders the current practically painless. The possibility of using this peculiar form of current in the production. of unusual effects will therefore be appreciated. Points to Consider.—Before starting work on any of the apparatus, the reader had best satisfy himself in his own mind just what feature of entertainment work he desires to take up. This section deals with the construction of practically every useful form of high frequency apparatus designed especially for theatrical demonstration. The assembly of the entire lot of apparatus as described would entail a considerable expenditure of time and money and there are cases where this outlay is scarcely justified. For instance, the platform lecturer would scarcely care to burden himself with the costly and cumbersome equipment so essential to the performer on the stage. For the benefit of readers to whom this elaborate equipment does not appeal, a summary of the various types of outfits will be made in order that the worker may make an intelligent selection whether he be a modest "suit-case" lecturer or vaudeville performer, a parlor entertainer, or a theatrical producer of the most extravagant type. The one big feature of any electrical offering is the high frequency work. This fact is admitted by dozens of per