in. THERMOMETRY. 263 



In the first case the resistances of the single conductors (except the 

 resistances of the two soldered places, which are exposed to constant tempe- 

 ratures, and show always the same resistance) may be different. In the other 

 case the resistances of all soldered places must he capable to be made equal. 



1048. Diagrams, illustrating the application of the Apparatus 

 for the Measurement of the Temperature of the Earth 



and of metal tools. Dr. J. Fernet, Breslau. 



1049. Normal Thermometer, divided in tenths of a degree 

 from -5 to +105 C. Ch. F. Geissler and Son, Berlin. 



1050. Chemical Thermometer from - 10 to +360 C. 



Ch. F. Geissler and Son, Berlin. 



2582. Collection of Thermometers. 



Dr. H. Geissler, Bonn* 



105Oa. Thermometer for Cooking, range to 6OO F. 



Harvey, Reynolds, and Co. 

 See Mrs. Buckton's book "Jiealth in the House," page 153. 



1051. Apparatus for determining the Temperature of Fusion. 

 (Compare the adjoined description.) Prof. Dr. Himly, Kiel. 



1052. Air Thermometer on the plan of Jolly. Compare 

 PoggendorfF s Annalen, Jubelband, 1873. 



University of Munich (Prof. v. Jolly)* 



1053. Thermopile on the plan of Melloni of 64 bismuth anti- 

 mony elements. Wesselhoft, Halle* 



1054. Thermometer Stick for measuring temperatures at 

 some depth. Ludwig Meyer, Berlin. 



The instrument, adapted for depths down to 3 feet, is chiefly distinguished 

 by the strength of its construction. 



The bulb is in the nickel clamp, which latter stands by means of mercury 

 in thermal connexion with the bulb. This mercury serves also as buffer ta 

 the thermometer bulb. 



The horn clamp is replaceable by an iron screw, which facilitates the intro- 

 duction of the thermometer into the ground. 



Care is taken that only the clamp be thermo- conducting, not the whole 

 tube. 



1055. Milligrade Thermometer. The milligrade scale is 

 one in which the interval of temperature between the freezing 

 and boiling points of mercury is divided into one thousand 

 degrees. John Williams, F.C.S. 



According to Dulong and Petit, mercury freezes at ^39* 44 C., and boils 

 at + 360 C. For convenience, assuming that the freezing point is 40 C., 

 the interval is therefore 400 degrees C., thus it follows that 2| degrees 

 milligrade are equal to 1 degree centigrade. Upon this scale the following 

 results are obtained. Water freezes at 100 M. and boils at 350 M., the 



