(float), an equipment box, and an antenna. The buoyancy unit is made of 

 styrofoam covered with fiberglas cloth impregnated with epoxy resin to 

 give it strength. The float is 3 feet by 3 feet by 3 inches with a 1-foot 

 by 1-foot hole through the center. (See Figure 1.) The equipment box is 

 mounted through the hole and held fast to the float by sheet aluminum 

 angles. Two eyebolts are mounted through the float to be used when it is 

 necessary to lower the assembly over the side of a ship into the water. 



The equipment box is made of plywood and is coated inside and out 

 with epoxey resin to assure its watertightness for the period of operation. 

 The top of the box is held in place with machine screws and has a rubber 

 gasket between it and the lip of the box to make a watertight closure. 

 The antenna mast is mounted through the top of the box. A ground plane 

 antenna, cut to operating frequency, is mounted on the top of the mast 

 with its feed line running down through the mast into the box. The 

 transmitter unit is attached to one side of the box and the batteries 

 that provide its power are located in the bottom of the box (Figure 3) . 

 A bar switch is located on the outside of the box and is used to turn on 

 the equipment . 



ACCELEROMETER 



The accelerometer is composed of a beryllium copper cantilever arm 

 mounted on a pedestal. The pedestal is attached to the transmitter unit 

 chassis (Figure 4) . An aluminum cup is mounted on the lever arm near its 

 free end. When the accelerometer arm moves, the aluminum cup moves in a 

 magnetic field created by a magnet from a dynamic speaker. The motion 

 creates eddy currents in the aluminum cup which are proportional to the 

 relative velocities of the arm and the base, thereby providing a damping 

 force. 



TRANSMITTER 



The SPLASHNIK transmitter appears at the top in Figure 4. The trans- 

 mitter uses a single tube which operates as a self-controlled oscillator 



