122 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
dent to transfer being small. About 20 per cent of eggs obtained here | 
were unimpregnated, but the relative loss in the season’s hatching was | 
small. Could the rack have been placed earlier on the Sandy River it 
is believed that larger collections could have been made, the migration 
of fish having been in progress two months before completing the rack. 
The liberation of fry was commenced December 29, continuing almost 
daily, as they developed, until April 20, deposits being made in: the 
Clackamas River and in Clear Creek, a tributary. The young were 
scattered over an area of about 5 miles. In January the water tem- 
perature was very low, and as a result of ice formation in the troughs | 
the flow was almost cut off. In the cold water the development of fry | 
was retarded, and but few were released during the month. Those 
released in February amounted to about 1,000,000, in March to 1,500,000, — 
and in April to about 1,000,000, the total reaching 4,100,000. 
After the termination of the egg-collecting season the racks and | 
inclosures on the Clackamas were removed and stored above the freshet 
line. From the commencement the pump was required to supply the 
hatchery, it being employed throughout November with the exception 
of three days. It was also used occasionally in December, but after 
December 21 there was, as a result of rainfall, sufficient brook water. 
On February 1 and 2 snow falling in the brook compelled constant 
attention to keep the water flowing. Once during February and again 
early in April Clear Creek was very high, floating one end of the bridge. 
On February 7 there were received from Northville Station 20,000 
eggs of brook trout. These arrived in good condition and hatched with 
slight loss, but the young began dying just before the sac was absorbed, 
all soon perishing. After March 31 the station force was reduced. 
AQUARIA, CENTRAL STATION, WASHINGTON, D. C. (L. G. HARRON, IN CHARGE). 
Both fresh-water and marine species were successfully maintained for 
purposes of study. Before the expiration of the fiscal year the super- 
intendent was temporarily transferred to Chicago, where he was in 
immediate charge of the salt-water section of the aquaria maintained 
by the United States Fish Commission. The salt-water section at 
Chicago having proved relatively more successful than the fresh-water 
section, it is apparent that studies carried on at the aquaria in Wash- 
ington brought about the result, the water in Chicago being circulated 
and aérated after the processes developed here. 
In July, 1892, an experiment was made looking to the reduction of 
temperature in the aquaria by applying ice to the pipes in which salt 
water was circulated, but the consumption ran up to about 2,000 pounds 
per day, making the cost too great. No attempt has been made to 
reduce temperature by application of compressed air. The salt water 
being in circulation and subject to surrounding air temperature, reaches 
a high point in the warm months, attaining 88° in August. In winter 
it is also subject to low temperatures, which, however, are not so 
_ extreme, the surrounding air being tempered by means of artificial 
