108 



DAVID G. CARGO 



simple distribution system with a constant- 

 head supply so that the control of the vari- 

 ous taps is not as critical as it would be if 

 it were a closed, pressure-type system. 

 For distribution to the tanks, an under- 



sized hole is bored in the bottom of the 

 trough, a tap is run througli the hole, and 

 a hard-rubber petcock is threaded into the 

 hole. Our original design included weirs 

 at several places (fig. 5) which were de- 



FiGUEE 5. — Plan of distribution trough. 



signed to maintain a level in the trough. 

 Actually, only the weir at tlie discharge 

 box is required; the remainder have been 

 removed. 



In use, the trough has required a regular 

 scraping and removal of the accumulated 

 fouling. Fortunately, most of this foul- 

 ing occurs in the first one-quarter of the 

 path that the incoming water travels. Ac- 

 cess to the trough from the second floor of 

 the research building is provided by a 

 wooden plank embedded in the concrete 

 floor. Thus, the boring of an access hole 

 is an easy matter. 



The aquarium tanks, shown in some de- 

 tail in figures 6 and 7, have proved very 

 successful. The stainless-steel bolts can 

 be covered with a synthetic-rubber com- 

 pound. The condensation on the inner 

 walls has not proved bothersome ; however, 

 some leakage has been experienced so that 

 the groove for carrying off condensation 

 has seen considerable use. The problem 

 of adequately sealing the glass to the con- 

 crete has not been completely solved, but 

 we have not considered the slight leakage 

 worth the effort of resealing these places. 



Several other features of the tanks merit 



