ARTIFICIAL INCUBATION. 



1013 



struction, ease of management, and small cost have rendered them 

 successful, and placed.them within the reach of all. , 



The Graves Incubator. 



This is a Boston machine, and shows great study on the part of 



the inventor. As the apparatus is shown in Fig. 1363, at the bottom 



•is the cold-water tank for egg-moisture„ then follows the egg-tray, 



Fig. 1363. — The Graves Incubator. 



above this the hot-water tank, and at the top the temporary 

 " mother." The heat regulator, the difficulty of all machines, is 

 shown. The lamp G heats the boiler H, which communicates by 

 tubes with the hot-water tank. J, J are lamp oil-tanks. Under the 

 heating-tank run two glass tubes filled with alcohol, which at the 

 outer end communicate by the bent tube L with the cylinder M, 

 containing mercury, which has a piston float and rod N. When the 

 temperature of the tank rises above that for which the valves are ad- 

 justed, the expansion of the alcohol in the tubes acting on the 

 mercury in M, forces up the piston-rod N. The upper end of this rod 

 is attached to a lever O, pivoted on the top, but moving freely at the 

 outer end. Above, the free end of the lever is connected by a rod 

 R with a valve P, and below, by a spiral spring, with the lamp. 

 When, therefore, the piston is raised, the valve P opens, and the over* 

 heated air escapes. Q is a slide at the bottom to lower it still faster, 



