92 INCUBATING OVENS AND THERMO-REGULATORS. 



maintain a small flame which must not be sufficient by itself to keep 

 up the desired temperature in the water bath. 



Altmann has recently (1891) described a thermo-regulator which 

 is made by Miincke, of Berlin, and which is shown in Fig. 65. This 

 is said to act with great precision. It is a modification of Reichert's 



FIG. 65. 



FIG. <>6. 



regulator. Its mode of action will be readily understood by a refe- 

 rence to the figure. 



A thermo-regulator which gives very accurate results, which are 

 not influenced by differences in pressure, is that invented by the 



FIG. 67. 



writer over thirty years ago. The regulating thermometer may 

 contain mercury only, or air and mercury, as shown in the thermo- 

 regulator for gas (Fig. 59). In the simplest form a large bulb con- 

 taining mercury is used, and a platinum wire is hermetically sealed 

 in the glass so as to have contact with the mercury (Fig. 66, a). 



