270 SEASON 1878-79. 



To take full advantage of the quadruple hatching-box I designed 

 a grille specially for it. The plan was similar to the ordinary 

 grille used in the 7-feet hatching-boxes (Fig. 69), only the 

 glass tubes were rather thicker, the hole in the strip of perforated 

 zinc being enlarged to bring the tubes closer together. This will 

 be easily understood from the longitudinal section (Fig. 194). 

 The two pieces of wood into which the zinc was fixed were slipped 

 into the frame, and held with four screws, so as to be easily 

 removed should it be necessary to replace a glass tube. The sides 

 were made sufficiently deep to allow four or five layers of salmon 

 ova to be placed on each grille ; although two layers, or about 

 7000 ova, were considered a fair stocking. The experiments with 

 this box were not satisfactory, the compartments being too large 

 to ensure an even distribution of the current through the whole 

 horizontal section, but I am of opinion that they indicated that, 

 so long as the ova are subjected to an even, uninterrupted flow 

 of pure water, the direction of the current is immaterial, and 

 if the water contains sediment, it will be deposited on the shell of 

 the ovum opposite to the direction of the current ; that is to say, 

 that an upward current keeps the lower portion of the shell clean, 

 and deposits sediment on the upper, while a downward current 

 keeps the upper portion of the shell clean, but deposits sediment, 

 though only to a very slight extent, on the under portion of the 

 egg ; the adherence is probably due to the absorption of water 

 through the pores of the shell. 



On the 17th March 1879 I experimented with various sizes 

 of zinc for screens, using S. fontinalis alevins. The result was 

 that the alevins passed through No. 9 perforated zinc with great 

 ease. I found No. 8 perforated zinc perfectly secure, and No. 7 

 dangerously small, as it not only was apt to clog and cause an 

 overflow, but the increased suction due to the increased depth 

 of water caused by the smaller hole, held the fish so tightly 

 against the screen, that many of them were unable to leave it if 

 they once touched. 



I also experimented on the quantity of water required to 

 carry trout. I netted the east 130-feet wooden pond, and selected 



