High Frequency Apparatus Page 119

PHYSICIANS' OFFICE EQUIPMENT 119 groups, one of which is the exciting apparatus comprising transformer, spark gap and condenser, while the other group embraces the oscillation or high frequency transformers, of which there are three. Of the latter, No. 6, the first instrument on the left in Fig. 1, is a coil of the Oudin type capable of producing a high frequency current of moderate potential for vacuum tube work; high potential current of very high periodicity for producing a spray or affleuve; and a current of great intensity, moderate potential and high periodicity for the removal of moles and warts by means of fulguration. The maximum spark length of this coil is about 3 in. The winding is coarse and the coil may therefore be used for high potential auto-condensation work. The variation in frequency and potential is effected by means of an adjustment of the number of primary turns. The coil shown in the center of the table, Fig. 1, is designed for X-Ray work. This instrument is an oil-immersed oscillation transformer which may be termed a combination of the Oudin and Tesla types since two Oudin coils are placed base to base to form a Tesla coil of sound mechanical construction. The X-Ray coil produces a thick and very hot 10 in. discharge between the points connected with its terminals. With a suitable high frequency tube, radiographs may be made of any part of the body in a comparatively short space of time. The oscillation transformer at the right, No. 8 in Fig. 1, is intended for general D'Arsonval treatment and its design is such that the work may be made to cover both autocondensation and diathermy. The latter is a comparatively new method of treatment which consists in placing a plate of metal on either side of the localized area to be treated and passing a very heavy current of from 800 to 2,000 milliamperes. The frequency, potential, and intensity of