Nikola Tesla Books
66 HIGH FREQUENCY APPARATUS In the mercury-turbine break, a stream of mercury is raised through the medium of a pump and projected in a fine stream against a series of metallic vanes with which it makes successive contacts. This device is even more difficult of contruction than any of the other types and no attempt will therefore be made to describe it in detail. The mercury-turbine interrupter costs in the proximity of $9.00 and it requires a small electric motor for its operation. It may be used on practically any voltage from six to 110. The relation of the vibrating interrupter to the rest of the coil is shown in Fig. 9, while the details of the interrupter are given in Fig. 10. Using the reference numbers in the drawing, 5 is a spring of phosphor bronze, 3 in. long, 1 in. wide and approximately 1/32 in. thick. To the end of this spring is secured the armature, 6, of soft iron, by means of four small screws. This armature may be turned from ½ in. soft iron bar or it may be cut from the end of a 1 in. rod of the same material. The contact, 7, is cut from a piece of fin. silver rod, drilled and tapped for the small screw that secures it to the spring in the position shown. The stationary contact, 8, is made of the same material and it is carried on the end of the 14-20 milledhead screw, 9, which is threaded into the stud of silver. The adjusting screw, 9, is carried by a cross arm of heavy brass bar, 10, which, in turn, is supported by pillars of brass, 11, at either end. The vibrating spring, 5, is supported at its lower end upon a bar of brass, 12, to which it is secured with screws passing through a washer plate. This construction is essential in order that the spring may have a definite point or edge from which to vibrate. The condenser to be shunted across the interrupter should be adjustable. The builder is strongly advised to purchase this condenser outright. The task of making up a condenser of tinfoil and paraffined paper is a discouraging
