154 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



of the tube to rise, pushing up with it its index, which is, in 

 its turn, left in its place where the maximum thermometer 

 has passed. The graduations of the second or minimum stem 

 of the thermometer are counted downward, and those of the 

 maximum stem are counted upward. As constructed by 

 Casella, it is said this instrument is extremely sensitive, con- 

 venient, and reliable. Quar. Jour. Meteor. Soc. of London, 

 1875,11,193. 



NEW SELF-EECOEDING THEEMOMETEE. 



In constructing a thermometer in which the dilatation of 

 the metal shall give the measure of the temperature of the 

 air, Tremeschini states that he has endeavored to eliminate 

 the inconvenience peculiar to the nature of glass by making 

 use of a metallic band as an indicator of the temperature. 

 In his thermometer, which he exhibited lately to the French 

 Meteorological Society, he employs a band of copper slightly 

 platinized in order to preserve it from oxidation. This band 

 is nine centimeters long and seven millimeters broad, and has 

 a thickness of one twentieth of a millimeter, and is therefore 

 extremely sensitive to atmospheric temperature changes : 

 it is coiled about a central axis, very much like the hair- 

 spring of a watch, and is contained within a case similar 

 to that of an ordinary aneroid barometer. The temperature 

 is read on the face of the thermometer bv an index, which 

 may even describe an entire circle in passing from 40 to 

 + 100 Fahrenheit. JVouv. Meteor., 1875, 14. 



OX THE EXPANSION OF INDIA EUBBEE BY HEAT. 



According to the studies of Schmulewitsch, based in part 

 on the studies of Puschl and Exner, as well as his own ex- 

 periments, the somewhat anomalous behavior of caoutchouc 

 under the influence of heat may be expressed by the follow- 

 ing four propositions : First, caoutchouc is a body whose 

 density is a minimum at a certain temperature. Second, this 

 minimum temperature changes with the mechanical exten- 

 sion, being lower the more the body is extended by the ap- 

 plication of some external force. Third, in the case of caout- 

 chouc unexposed to any strain, the temperature of the min- 

 imum density is higher than ordinary temperatures, but 

 approaches the latter by heating ; its co-efficient of expan- 



