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II. Temperature Box. 

 This temperature box is made of galvanized iron. It is 25 cm. long, 

 9 cm. wide and 3 cm. deep, all inside measures. It is held to the stage 

 of the microscope by means of a curved iron clamp hooked over the edge 

 of the box at A. Near the lower side B is a rectangular slit 4 cm. wide 

 and 4 mm. high, extending entirely across the box for the reception of a 

 slide caiTying the object for observation. By noticing Fig. 2 it will be 



Fig. 2. 



seen that the slit. B. is elevated about 2 mm. above the bottom of the box 

 as at C, thus allowing the hot or cold water used to flow under and all 

 around the space occupied by the slide. By this means the temperature 

 may be increased or decreased as desired, in B to the most perfect state 

 of etiiciency possible in such a simple contrivance. At D is a cylindrical 

 tube 3 cm. higli and 2.."> cm. in diameter for the reception of the objective. 

 In Fig. 2 both the tube D and the side of the box toward the observer 

 are cut partly away to show the interior. The top is provided with a 

 lid. By means of a proper mixture of salt and ice it is possible to reduce 

 the temperature in the slit B, as shown by the thermometers kept con- 

 stantly in the spaces E and E\ to zero centigrade or below. If, however, 

 a high temperature is desired, this may be accomplished by placing a 

 flame under the end of the box F which projects over the stage of the 

 microscope. Or one may arrange a vessel, somewhat higher than the 

 box on the stage of the microscope, and by placing a lamp under this 

 vessel, which is nearly tilled with water, easily heat it to any desired 

 temperature as shown l)y a tliermometer. This heated water could then 

 be siphoned into the box A and out again, and in this way the desired 

 temperature in B obtained. The inflow and outflow to A can easily be 

 regulated and made uniform l)y opening or closing pinch-cocks fastened 

 on the rul)ber tube. Injury to the microscope is prevented by a sheet of 

 asbestos placed on the stage. Tliis temperature box can be turned either 

 to the right or left or turned and used in anv anale of 180° or less. 



