632 



APPENDICES. 



water-chamber, aud the others for thermometers and for regulating 

 the air supply in the cavity of the cylinder. The cylinder is con- 

 tinued below by a cone, also double- walled, and there is a perforated 

 grating at the line of junction of the cylinder and cone. The cone 

 terminates in a projecting tube provided with an adjustable 

 ventilator. The apparatus is fixed on three supports united to 

 one another below. One of them is utilised for adjusting the height 

 of the heating apparatus. Situated above this leg is the heat- 

 regulating apparatus (Fig. 265), attached to a circular, lipped 



aperture in the outer wall of the 

 incubator. To the lip is fixed with 

 six screws the corresponding lip of 

 a brass box, with a tightly-stretched 

 diaphragm of indiarubber inter- 

 vening. Thus the diaphragm 

 separates the cavity of the box from 

 the water in the interspace of the 

 incubator. The cap of the box, 

 which screws on, is bored in the 

 centre for the screw- pipe, by which 

 the gas is supplied. Another pipe 

 entering the box from below is connected with the gas-burners. 

 Around the end of the screw-pipe a collar loosely fits, and is pressed 

 against the diaphragm by means of a spiral wire spring. Close 

 to the mouth of the screw-pipe a small opening exists, so that the 

 gas supply to the burners is not entirely cut off even when the 

 diaphragm completely occludes the mouth of the screw-pipe. 



Fig. 265.— Sohlosing's Membrane 

 Regulatob. 



To work the apparatus the tube and plug must be removed, and 

 the water-chamber filled completely with distilled or rain water at the 

 temperature required. The caoutchouc plug is replaced and the tube 

 placed in position. Gas enters through d (Fig. 265), and passes through the 

 opening at its extremity into the chamber of the box. Thence it passes 

 through the vertical exit which is connected with the gas-burners. As 

 the temperature rises the water rises in the tube, and at the same time 

 exercises a pressure on every part of the walls of the incubator, and 

 hence on the diaphragm. In consequence of this, the diaphragm bulging 

 outwards approaches the end of the tube d, and gradually diminishes the 

 gas supply. As a result the temperature falls, the water contracts and 

 sinks in the tube, and the diaphragm receding from d, the gas supply 

 is again increased. By adjusting the position of the tube d to the 

 diaphragm, any required temperature within the limits of the working of 

 the apparatus can be regulated to the tenth of a Aegree— provided (1) 

 that the gas supply is rendered independent of fluctuations of pressure 



