222 SKC. 8. HEAT. 



tions of temperature are thus readily seen by a large class, e.g., the expansion 

 of the glass of the bulb causing a momentary retreat of the index hand, is 

 seen to be the first effect produced by heat on the bulb. By making the scale 

 on glass the dial can be projected on a screen and determination of specific and 

 latent heat made before a large class ; electric contact can also be made by 

 the hands, and thus a self-registering thermometer constructed. The instru- 

 ment was made by Mr. Yeates, of Dublin. 



1011. Various Thermometers, of different kinds, in metal, 

 ivory, porcelain, glass, and wood. Elliott Brothers. 



1012. Standard Thermometer. Elliott Brothers. 



1013. Insolation Thermometer, for determining the inten- 

 sity of the rays of the sun (maximum thermometer), with holder. 



Ch. F. Geissler fy Son, Berlin. 



1014. Eight Normal Thermometers, executed by Greiner 

 and Geissler, Joint Stock Company, Berlin. 



Imperial Admiralty Hydrographical Bureau at Berlin, 

 and Deutsche Seewarte in Hamburg. 



These thermometers are employed in the stations of the Naval Observatory 

 and in the Imperial Navy. 



101 5a. Thermometer, with corrected Freezing Point* 



W. Gloukhoff, St. Petersburg (Russia). 



This thermometer is constructed on a principle much used in Germany. 

 To it is added only a contrivance to render the scale more steady, and to 

 correct the error of freezing point, by raising or lowering of the scale. By 

 unscrewing the upper metallic cap of the thermometer, this contrivance 

 becomes visible. 



1016. Reaumur's Scale. Dring and Page. 



Formerly much used in Germany and Russia, now mostly in Norway and 

 Sweden, and some parts of Denmark. The zero of this scale is at the point 

 of melting ice. The interval between this and boiling point is divided 

 into 80 degrees. 



1017. De Lisle's Scale. Dring and Page. 



This scale is seldom used ; zero is fixed at boiling point ; the interval 

 between this and freezing is divided into 150 degrees. 



1018. Six's Thermometer on a porcelain scale (named 

 after its inventor, Mr. Six of Canterbury) for registering extremes 

 of temperature. Dring and Page. 



The indices are little pieces of steel coated with glass which are enabled to 

 retain their position in the tube by means of a hair fastened round them, and 

 by this means the highest or lowest temperature is recorded. 



lO18a. Six's Thermometer with a very flat bulb which 

 renders it as sensitive as an ordinary mercurial thermometer. 



S. G. Dent cm. 



