and can record velocities in salt water and 

 in fresh water, and can be used easily in 

 the field as well as in the laboratory. 



DESCRIPTION AND OPERATION OF THE METER 

 AS DESIGNED FOR LABORATORY USE 



The meter is made up of three main 

 parts as shown in figure 1: chassis (1), 

 rod assembly (2), and gun (3). Wherever 

 possible, parts are labelled to correspond 

 with the electrical diagram (fig. 3). 



The rod assembly (fig. 2) is brass 

 and houses the penlight lamp, photoelectric 

 cell, and propeller. Parts of the assembly 

 containing the lamp and the photoelectric 

 cell have been made waterproof by silver- 

 and soft-soldering. The photoelectric cell 

 is further sealed from contact with water 

 with plastic resin. The propeller shaft is 

 stainless steel mounted on bronze bearings. 



The gun assembly, constructed of 

 aluminum , houses the contact-register 

 counter switch. 



The chassis (5 inches long by 6 inches 

 wide by 4 inches high) is constructed of 

 aluminum (1/32 inch thick). It houses the 

 12AU7 tube, condenser, rectifiers, register 

 counter, transformer, potentiometer, and 

 main switch. 



When in operation, the rod assembly 

 is submerged in the water to the desired 

 depth. Care should be taken to be certain 

 that the propeller assembly is in direct 

 line with the water flow. The test is be- 

 gun by closing the switch (E) and releasing 



PROPELLER ASSEMBLY 



DRILL TWO HOLES THROUGH 

 BRASS FORWIRES- 



,4 THK PLASTIC CEMENTED- 

 " FOR WATERTIGHT SEAL 



BRASS RING i THK. INSERTED AT EACH END 



PROPELLER ASSEMBLY "" NBRONZE BEARING 



TOP VIEW- SECTION CUT AWAY TO SHOW 

 PROPELLER ASSEMBLY 



SHOWN 2XX SIZE 



Figure 2. — Detailed drawings of the portion of the rod assembly housing the bulb, photoelectric cell, 

 and propeller. 



