Nikola Tesla Books
HIGH FREQUENCY PLANT CULTURE 161 baseboard and cover of wood separated by two end pieces. The plates slide in grooves formed by ½-inch square strips of wood nailed to the base and cover. A bar of ½-inch by 1 inch copper runs across from one end piece to the other on either side and affords a means of connecting the many plates in multiple. This connection is accomplished by means of the special contact leads shown in Fig. 16, These leads are merely pieces of lamp cord tipped at one end with a lug and at the other with a contact made from a piece of spring brass ribbon bent into the shape shown in the drawing. The object of the contact is to establish connection between both plates of tinfoil when the spring is inserted. In making the connections to the bars on either side, the contacts are alternated in order that the plates may all be in multiple. That is, referring to Fig. 15, in starting to insert the contacts, on the one side the first contact spring is inserted between the first and second plate; on the other side the contact would be between the second and third; returning to the nearer side, the second contact is inserted between the third and fourth plates, and so on until all have been put in place. The contact with the first and last coatings are of course made by inserting the clip between the tinfoil and the wooden end piece, placing a small sheet of glass between the spring and the wood to prevent the metal coming into contact with the wood. When the four units have been made as described, they are to be connected up as shown in Fig. 14, the connecting leads being strips of copper ribbon. The setting up will receive due attention when the rest of the apparatus has been described. Construction of the Spark Gap.-Perhaps no one portion of the high frequency apparatus is more likely to give trouble and to require frequent attention than is the spark
