Nikola Tesla Books
PHYSICIANS' OFFICE EQUIPMENT 129 ing of a length of heavy incandescent lamp cord is soldered to each of the 3 outer turns on both sides of the helix and brought to its proper terminal in the cover of the case. The containing case should be of rather heavy stock and lined with sheet zinc with corners carefully soldered. The reader will note that when the cover of the case is removed the entire coil comes out with it and there is accordingly no necessity for attempting to make any connections underneath the oil which fills the zinc-lined case. When the mechanical work on the transformer is finished, the cabinet may be filled nearly full of transformer oil, or, if this is not available, double-boiled linseed oil may be employed. The oil should be made very hot before the transformer is lowered into it in order that the air may be expelled. The essential details of construction are clearly shown in the drawing, Fig. 3. Further discussion is not deemed necessary. The D'Arsonval Oscillation Transformer.-This is a standard "loose coupled" helix of the wireless type and it may be purchased complete for $12.00. It is simple of construction, however, and the builder, if he so desires, may purchase merely the edgewise wound copper strip, making the slotted hard rubber supporting posts and the wooden heads in his own work shop. The copper helix is 7½ in. in diameter and the strip may be purchased already wound at 15 cts. per turn. The primary or lower portion of the transformer comprises 8 turns while the secondary or upper portion contains 22 turns. There is no electrical connection between the two, the closed oscillating circuit taking in the primary while the patient's body is connected with the secondary. Assembly. The entire lot of apparatus is assembled as shown upon a substantial table fitted with a shelf beneath.
