260 SEC. 8. HEAT. 



101 5a. Thermometer, with corrected Freezing Point. 



W. Gloukhqff, St. Petersburg. 



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 melt- 

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

 into 80 degrees. 



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



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

 between this and freezing point 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 Fage. 



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. 



1018a. Six's Thermometer with a very flat bulb which 

 renders it as sensitive as an ordinary mercurial thermometer. 



S. G. Denton. 



1018b. Six's Thermometer with mercurial wet bulb ther- 

 mometer attached, thereby combining four instruments in one, 

 namely, maximum, minimum, hygrometer, and present tempera- 

 ture. S. G. Denton. 



1019. Long Brass-Cased Thermometer. Showing the 

 difference in length of the mercurial column after being pointed 

 and divided with the whole length of the tube immersed in water 

 at the various temperatures between 32 and 212 ; the same with 

 the bulb only in the water. Dring and Fage. 



1020. Very delicate Spiral Bulb Thermometer. Ex- 

 tremely sensitive, capable of indicating small variations of tem- 

 perature. Dring and Fage. 



1022. Standard Thermometer, calibrated throughout, 



Dring and Fag c, 



A standard thermometer divided on the tube, used for purposes where 

 great accuracy is required. The tubes used for these thermometers are 

 selected with great care, particular attention being paid to the uniformity of 

 the bore. The method of ascertaining this is usually performed as follows : 

 A portion of mercury is introduced into the tube, and the length it occupies 

 is noted ; it is th%p carried a little further on, and its length compared with 



