116 BULLETIN OF THE UNITED STATES FISH COMMISSION. 
I had from time to time been experimenting on a small scale with 
young cod, and found that the water must have, besides the proper tem- 
perature, a specific gravity of 1.022, which is absolutely necessary in 
order to keep them from sinking to the bottom. If the specific weight 
of the young fish is more than that of the water they have too great a 
tendency to sink ; and as their swimming power in their early stage is 
very small, they will touch the bottom at last, no matter how they 
struggle against it, and then their destruction is certain. 
In view of these facts, it was considered necessary to construct a 
basin in such a place and in such a manner that the saltness of the water 
and its renewing would be under absolute control. I therefore proposed 
one entirely separate from the sea, which could be filled with proper sea- 
water by aid of a steam pump. A good place for such a basin was easily 
found. A plan of such was sent to the branch directors, which they 
accepted, and the work was commenced and finished during the fall of 
1885. The dimensions of the basin are: Greatest length, 43 meters; 
greatest breadth, 20 meters ; greatest depth, 5 meters [about 140 by 66 
by 16 feet]. 
The capacity is about 2,500 cubic meters [about 88,000 cubic feet], and 
its overflow lies about 8 meters [26| feet] above sea-level. It is situated 
in a natural indentation in the cliffs and has a wall 40 meters [131J feet] 
long to the south, and one 15 meters [49^ feet] to the northeast. The 
pumping is done by a small steam-engine and a windmill, erected in 
the neighborhood ; but they are found rather too weak to perform the 
work satisfactorily, especially as a hill to the southeastward shelters the 
windmill from that direction. 
During the month of April the basin was cleaned out and filling it was 
commenced, during which several kinds of sea-plants were put in. On 
the 3d of May about 500,000 young cod, hatched on the 27th of April, 
were put into it; the pumping continued steadily until the basin was 
filled, and afterwards at certain intervals. 
With regard to the further progress of the young cod, I copy from my 
day-book as follows : 
May 3-8. — Saw the fry every day, most of them at the eastern side. 
They never swim in schools, always by themselves. 
May 9. — Development goes on. In the most of those I examined was 
seen a yellow content. 
May 10.—The greatest number were seen about the mouth of the pipe 
through which the water was pumped in, probably because the water 
was fresher there than elsewhere in the basin. 
May 11.— Continue to grow. Yellow spots are seen on the head and 
backs. Great numbers of crab larvae (zoea stage) are found in the 
basin, and are very lively, swimming about near the waste- water over- 
flow. 
May 13.— About 5,000 young fry were put in the basin. Cod fry 
grow steadily* and* as mentioned before* are in greatest numbers about 
