54 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
1890-91. 
An additional steam pump, as a reserve in case of accident, was pro- 
vided. In the month of July, 1890, the obstruction rack was placed in 
the dam to arrest the upward passage of the adult salmon. <A gate with 
sheerbooms, for facilitating the onward passage of drift timber on high 
water, was introduced into the dam. Five days were consumed in re- 
moving the saw logs, which had grounded in the seining area, but all 
could not be cleared out, and the strong current incident to their pres- 
ence being a barrier to successful operations in hauling, it became nec- 
essary to use gill nets in the capture of the adult fish. Owing to the 
construction of a dam in the river below the station and the operation 
of nets by commercial fishermen, the ascent of a great number of fish 
was hindered. 
The collection of the eggs was commenced September 16, 1890, and 
the first hatching took place about the end of October. Kggs continued 
to be taken until November 16, the total from 1,094 females amounting 
to 5,860,000. Of these, 700,000 were delivered October 22 and November 
5, 1890, to the Oregon fish commissioners. ‘The remainder were hatched 
at the station and the fry placed in Clackamas River and its tributa- 
ries. The fry produced were 4,902,000 or about 95 per cent of the eggs 
retained. 
In January, 1891, the hatching took place so rapidly that use had to 
be made of the troughs of the improvised hatchery of the previous year, 
to prevent suffocation among the fry. Hatching terminated in Febdru- 
ary, the fry having been liberated from week to week, within a river 
scope of 3 miles, as they arrived at the age to begin to take food. 
About 1,000,000 were released subsequent to March 1. In the months 
of May and June, 1891, the rack and traps were again overhauled and 
put in position for the operations of the coming season. 
AQUARIA AT CENTRAL STATION, WASHINGTON, D.C. (W. P. SEAL, IN CHARGE). 
1889-90. 
In July, 1889, a new hot-air engine, equipped with vuleanized rubber 
pump and piping, was introduced for circulating the salt water, the 
brass piping being laid aside. By February, 1890, the water was ren- 
dered so clear by means of filters that all objects could be distinetly 
seen. The salt water lost by leakage was made up by supplies produced 
at the station by dissolving Turk Island salt in filtered water at the 
proper density; 1,000 gallons of sea water from Chesapeake Bay were 
furnished by the steamer Fish Hawk, 
Collections of salt-water objects were received throughout the year, 
principally from Woods Holl Station, some being received from Glou- 
cester Station, Mass., and others from Portland, Me., and the New Jer- 
sey coast. Fresh-water specimens were derived from the fish ponds, 
