54 



DEPAkTMElfT OP TBE NAVAL SERVICE 



8 GEORGE V, A. 1918 



Last year, 1914, because of the excessive leakage of water from the pound, the 

 Board approved of the location of an experimental rearing plant of four boxes at the 

 southwest end of the pond, and my report upon the operations of that year has been 

 already published. 



LEAKAGE. 



On December 18, 1914, the Board was notified that the leakage, which had per- 

 sisted throughout the i>revious summer, had been stopped, and that there was at that 

 date a depth of 6J feet of water in the pound at low tide. During the winter of 1915, 

 however, the leakage again developed and was again rei^orted stopped on June 26, 

 1915. At this date there was said to be a depth of 5 feet 8 inches of water at low tide. 



On my arrival, July 3, 1915, the pound was again leaking, not copiously, it is 

 true, but sufficiently to show that in the course of a few days or weel^s the rearing 

 boxes, 4 feet in depth, would likely be resting in the mud. As a precaution, there- 

 fore, against possible injury to our larv?e, the boxes were reduced in depth to 2^ feet. 

 On the assumption that there would be, as intimated, 6^ feet of water at low tide, a 

 space of 4 feet would intervene between the bottom of our shallow boxes and the mud 

 beneath. 



At Wickford, R.I.- — the original home of the plant — the depth of water below the 

 boxes is 12. feeti at low tide, excepting at one corner, where it is only 5^ feet. At 

 Long Beach it was hoped that a depth of 4 feet might suffice to test the scheme. Last 

 year at low tide there were only between 20 arid 22 inches of water below our boxes ; ' 

 this year, after operating our plant for seventeen days, the boxes were resting in the 

 mud, so great was the leakage. 



Fig. 2. — West side of cement puund showing leakage of water Over tlie ironrods at the 

 upper left hand coi-ner of the illustration can be seen the gearing of the rearing apparatus inside 

 of the cement pound. 



hes 



At the extreme low water of August 7, two of the boxes were resting 5 inches ^^^ 

 in the mud. Measurements at eleven diflerent points around our apparatus gave the 



