SEA-FISHERIES LABORATORY. 159 



rows of boxes which, allows the free ends of the boxes to 

 float up. The rod is then suddenly released, and the 

 boxes depressed rapidly into the water, which is forced 

 up in powerful currents through the perforated bottom of 

 the boxes. This separates the eggs in all directions, but 

 without injury to the developing embryos. 



The mechanism employed in other establishments 

 which use the same kind of hatching apparatus is driven 

 by a water wheel. This wheel turns a cam which has a 

 lever resting on its rim. One end of the lever is weighted 

 to give the necessary pull to the wires that suspend the 

 rods. The other end has the main wires attached, and 

 from these branches are led over pulleys to the various 

 weighted rods. As the cam revolves the lever is alter- 

 nately raised and depressed so pulling up and then 

 releasing the wires. 



The arrangement of the hatching apparatus at Piel does 

 not readily lend itself to the adoption of this method. 

 Some other system had, therefore, to he planned, and 

 after various experiments, the apparatus now adopted by 

 us was devised. This apparatus has given complete satis- 

 faction during the last season, and as it is less compli- 

 cated than the older systems, a description and illustra- 

 tion may be useful to others, and will now be given. 



The apparatus may be briefly described as a direct- 

 acting balance of the beam and scale pattern. It consists 

 in the main of a balanced beam (see Plate A, 3). One 

 end of the beam is attached to the middle of a light 

 framework, which carries the wires connected to the 

 weighted rods (5). The other end bears a frame contain- 

 ing a " tumbling " box (4) of a similar design to those 

 used in automatically measuring rainfall, washing photo- 

 graphic prints, hushing drains, &c. The box is so con- 

 structed that when empty it remains in a horizontal 





