Nikola Tesla Books
HIGH FREQUENCY PLANT CULTURE with the dimensions of the various pieces. 167 The secondary cylinder is of cardboard and made expressly for the purpose. In designing the coil, the writer has purposely chosen, wherever practicable, dimensions which correspond with the standard sizes of the parts now obtainable through electrical manufacturers. Accordingly, the cylinder has been made eight inches in diameter and 13 inches long. The wall is about one fourth inch thick. Into each end of the cardboard cylinder is fitted tightly a head turned up from whitewood and soaked for an hour in melted paraffin. The heads are drilled for the terminal post and the brass stud, respectively. The details of the terminal are given in Fig. 20 but the stud has been omitted, since its construction is obvious. The next operation is to treat the cardboard cylinder to three coats of shellac, making certain that each coat is bone-dry before applying the next and baking the cylinder after each coat in a moderately warm oven. Secondary cylinder of cardbord read -85Freqd To fit cardbord cylinder regd Heads for cylinder of whitewood sow cuts deep Support for primary (of block fibre 4red Overhead Base of whitewood regd 14 Soft rubber feetPrunary clip copper Primary a turns of edgewise wound copper strip With of strip regid Ethickness hside diam of helix of Terminal post of black fibre-rega Ground Diagram of connection I-regd Fig. 20.-Details of the oscillation transformer
