616 EEPORT OP COMMISSIONER OF FISH AND FISHERIES. 



low the surface; the refuse matter, including the ISaprolegnia, constant- 

 ly flowed off. The engine was worked night and day. When the stock 

 on hand was small the engineers also attended at night to the cylinders 

 and cones, but during the height of the season, when everything was 

 filled, night and day attendants were required. Some little difficulty 

 was at first experienced with the cyUnders in time of storm, a very lit- 

 tle increase in wind or wave occasioning too much agitation of the water 

 and eggs within the cylinders, and our first warning of this danger was 

 the loss of over 300,000 eggs, by a strong wind and sea setting against 

 the cylinders containing them on one side of the barge. This we were 

 afterward able to prevent in part by stopping the machinery and allow- 

 ing the wave alone to give the movement to the eggs within the cylinders. 

 A screen or breakwater might, however, easily be devised by placing a 

 frame work outside the cylinders, reaching a little below the water, and 

 nailing or fastening to it either canvas or thin boards ; not being pre- 

 pared with this device during the present season, it was thought best to 

 use the cones to the largest extent before utilizing the cylinders, and some- 

 times, when bad weather threatened, we took the precaution to remove 

 the eggs and fish from the cylinders to the cones inside the building, if 

 any of them happened at the time to be empty, as was exj^lained in my 

 report of J 877. Very much less loss was experienced by this apparatus 

 than could be expected from any form of floating box where only side 

 currents are to be depended on. 



Where a continual river current is found, the cheaper floating boxes 

 may be used quite as efficiently, except for the greater area required ; 

 but the larger i^ortion of the shad-spawning grounds being within tide- 

 water and where currents are very slight, the great advantage of this 

 certain and constant agitation of the water is readily appreciated. 



As in all artificial i>ropagation of fishes the i)resence of a skillful expert 

 is necessary ; trusting the work to beginners and those who have little 

 experience and ability in fish-hatching will afford as small results as it 

 does with any other api^aratus. 



A small experiment was made with the Chase jar. This Mr. Oren M, 

 Chase has used at Detroit for the past four years in hatching white-fish. 

 It was found to work with quite as much efficiency in hatching shad, and 

 it is quite probable that with some modifications to suit the different con- 

 ditions of shad-hatching it would be found to excel everything else in the 

 concentration of space and hatching a very large quantity of eggs in 

 masses contained in quite small vessels. 



A device invented by one of the working members fo the corps, Mr. 

 W. T. W^roten, also deserves notice. It embodies the principle of the 

 Chase jar, except that instead of applying the current through a rubber 

 tube and diffusing it from the center of the vessel it is applied through 

 vertical funnels or channels on the sides of the vessel, forcing the water 

 in through a narrow space or slot extending round the bottom. This is 

 an advantage in the fact that the vessel being made sufficiently small — 



