114 COMMISSIONERS OF INLAND FISHERIES. 



they are removed and the rearing box raised and thoroughly washed . 

 (Plate XV.) The insides of the boxes are covered with a thin coating 

 of copper paint in order to prevent them from becoming overgrown. 

 This is quite an important matter because the fry often become 

 contaminated from contact with the foul sides of the car. Care in 

 seeing that there are no holes with a diameter greater than ^ of an 

 inch in the cars, and then guarding against their becoming foul, are 

 the two most essential points in the care of the cars. 



5. CONSTRUCTION AND ADJUSTMENT OF THE PADDLES. 



The paddles used at Wickford are two-bladed, not unlike those 

 used overhead in restaurants. (Plate XX.) Each blade is made 

 of one-inch cypress and is 8 inches wide at the end nearest the paddle 

 shaft, and tapers to about 4 inches at the outer end. The blades are 

 fastened by clamps to a piece of -f- inch galvanized iron pipe, which 

 is placed on the under side. (figs. 4,5.) Between the two blades 

 there is a cross coupling, into one opening of which a short vertical 

 galvanized iron pipe is screwed (fig. 6) which sets over a stud-bearing 

 in the bottom of the rearing car. (fig. 7) In the opposite opening 

 of the cross coupling is a long vertical galvanized pipe (fig. 8) which 

 is used as a shaft for that part of the paddle which is under water, 

 and connects with the shafting and gears as described in section 3, 

 page 110. The paddle used at present is broadly beveled on each 

 side, though the double beveling is unnecessan\ The length of the 

 paddle should be sufficient to clear the sides of the box by about 3 

 inches when revolving, and should be raised about the same distance 

 above the bottom. The blades of the paddle should, furthermore, be 

 painted white so that the lobsters will avoid them. 



Too great care can not be exercised in the proper adjustment of 

 the paddle. With a paddle of the above width and length, a little 

 less than ten revolutions per minute are sufficient. The angle which 

 the paddle should oppose to the water is a matter which requires 

 experience to determine. It is, however, a very important factor. 

 Many times in two lots of larvae, under apparently similar conditions, 



