REPORT OF COMMISSIONERS OF INLAND FISHERIES. 21 



vse,, through the absence of fungal growths and parasites^ were much 

 healthier and sturdier than was formerly the case. 



In the year 1901 a mechanical device was employed for the first 

 time to keep up the motion of the water, and in connection with it 

 an enlarged and improved form was given to the whole hatchery, 

 and this essentially has been retained. 



The arrangement of the hatchery, housed on a large float can 

 easily be_ seen from the illustrations.* In the midst is a so-called 

 "houseboat," with two superstructures, a laboratory and a tool 

 room in which is a small, 2h HP gasoline motor. The middle por- 

 tion carries two small hatching bags, 6 by 6 feet on the bottom 

 and 4 feet deep. On each side, connected with the middle portion 

 is a float built of 6-inch beams and kept up by barrels. In the spaces 

 between these beams are in each case five large hatching bags, 

 12 by 12 feet on the bottom and 4 feet deep. 



The hatching bags consist of sail-cloth and have in the bottom 

 a large window filled with wide-mesh gauze, which allows the water 

 free entrance. They are fastened to sliding poles, on which they 

 can be lowered or raised at will. 



While the machine is running the upper rims of the bags are 

 above the water. To the shafting on the float are attached a num- 

 ber of tw^o-bladed propellers, so that one is in the middle of every 

 hatching bag and by its turning keeps the water within the hatching 

 bag in constant motion. The motion is very slow^ and gauged to 

 about ten revolutions a minute. The action can be regulated by 

 adjustment of the propellor blades on the axle. It produces an 

 upward w^hirl in the water strong enough to keep constantly in 

 suspension the larvae and the finely divided food. The vertical 

 axle of each propeller is connected to horizontal shafts by means 

 of gears. The horizontal shafts on their part are carried often long 

 distances, by means of repeated couplings, to the motor. The con- 

 nection of the shafting of the great side floats with the main shaft 

 on the middle pontoon requires a kind of ball joint and a very flex- 



[* Illustrations showing the arrangement of the hatchery can be found in previous reports, 

 especially in the report for 1905.] 



