18 KEPOET OF COMMISSIONER OF FISH AND FISHERIES. [16] 



each cylinder iiiul the cam moticu put in operation, which gives them a 

 very gentle ascent, occupying about three-quarters of the revolution ^ 

 the descent, being accomplished during the remaining fourth of the 

 revolution, is made more rapid, causing the eggs to rise from the bot- 

 tom and circulate freely through the water at every downward movement. 



The cylinders require but little attention during the hatching process^ 

 and, in moderately smooth weather, are undoubtedly equal, if not su- 

 perior, to all other appliances for shad hatching. They can also be made 

 available for the development of all non-adhesive eggs, no matter what 

 their specific gravity, as the requisite motion can be attained by simply 

 modifying the form of cam. 



Plate IV shows some of the apparatus used by the United States Com- 

 mission in fish hatching: the spawn pans of marbleized iron in which 

 the eggs are i)laced for impregnation; the spawn i)ail in which the im- 

 pregnated eggs are placed for transportation to the hatching establish- 

 ment; the dipper in which all eggs are meatfured when received on board^ 

 and the hatching cone, with goose-neck unscrewed; the three kinds of 

 cylinders used, the large one with the solid tin body, a smaller one with 

 a combination body of copper and wire gauze, and a third with gauze 

 body. 



Between the cylinders stands a funnel, with fine wire-gauze bottom, 

 used for siphoning water from hatching cones without removing eggs 

 or young fish. 



DREDGrING MACHINERY. 



The hoisting and reeling engine, the main features of which are given 

 in the general description of machinery, stands on the promenade deck 

 immediately forward of the foremast, as shown in the plates V and YI. 



The drum, or reel, holding a thousand fathoms of steel-wire dre<lge 

 rope, three-eighths inch in diameter, is carried on the main shaft of the 

 engine and driven by friction gear. An automatic guide lays the rope 

 fairly on the reel when heaving in. One man attends the engine, hoist- 

 ing and lowering the trawl and dredge without the necessity of touching 

 the rope by hand. 



The dredging beam is 36 feet in length and 10 inches in diametery 

 the heel secured to the foremast by a strong goose-neck 5 feet above 

 the deck. The forward end, when not in use, rests in a cradle on an 

 iron frame in which the ship's bell is suspended. 



There is an iron baud at the boom end for fore-and-aft guys; the 

 topping lift band is about 3 feet from the end, and has a strong link 

 on the under side, to which is hooked the dredging block. The topping 

 lift is composed of two 14-inch double blocks and a4-iuch manila rope. 

 The ui3i)er block is shackled to an iron collar on the foremast 3 feet 

 below the eyes of the rigging. There is a strong sheave in the boom 

 inside of the lower topping-lift block, over which is rove the pendant of 

 a tackle used for hoisting the bag of the trawl on board when the weight 

 is too great to be managed by hand. 



