X-Rays, Apparatus and Methods Page 11

the tube, rapid fluctuations of the vacuum, and general deterioration of the tube. We doubt whether, with any coil of size suitable for X-ray work, a rate of break greater than 5,000 per minute should ever be employed.

Tesla Coil or Induction Coil — Which? — Having carefully examined the results, apparatus and methods of others all over the country, devotees some of the "high-frequency" coil, some of the induction coil, and having made many and careful experiments with both forms of apparatus ourselves, we favor the induction coil. Our reasons for this preference are briefly stated:

(a) Simplicity. — One coil instead of two.

(b) Ease of Manipulation. — There being more than double the number of factors to attend to in the Tesla coil than in the induction coil.

(c) Cleanliness. — The "high-frequency" coil requires an oil bath, which must be renewed from time to time to avoid gumming. It is difficult, also, to find an oil which will not, eventually, act upon the insulation of the wire by virtue of the acid or other impurities which the former may contain.

(d) Sharp Definition. — The "high-frequency" coil produces an alternating discharge — thus with the double focus tube giving us two sources of X-radiation and consequent blurring of the image. If a single focus tube be used, the discharge in one direction is either lost or tears off particles of the platinum reflector, thus blackening the tube and soon destroying its effectiveness.

(e) Noiselessness. — This, from the surgeon's and physician's standpoint is, perhaps, the most important consideration. With tube in action, the induction coil is practically noiseless, save for the low hum of motor or vibrator. Improperly designed vibrators often rattle and rasp in a very irritating manner. In the "high-frequency" coil, however, the disruptive discharge over the air gap is the vital cause of its action. It is much more violent than a discharge of corresponding length from the induction coil, being of a rattling, cracking character. That such noise cannot but have a most unpleasant effect upon the patient who comes