104 



Chemical PhilosophiJ. 



of this kind to the Royal Society of London. It 

 was soon found that this fluid was preferable to 

 all others, being more homogeneous, more easily 

 freed from air, more regularly expansible by dif- 

 ferent degrees of heat, and more difficult to con- 

 geal. Mr. Fahrenheit also proposed a new mode 

 of graduating the instrument. His thermometer 

 has since come into general use in Great-Britain, 

 America, and in the various parts of the world in 

 which British habits prevail. 



In 1730 M. Reaumur, a French philosopher, 

 constructed a thermometer on a new plan. He 

 adopted a mode of graduation different both from 

 Newton and Fahrenheit, and resumed the use 

 of alcohol. His plan was, of course, still far from 

 being perfect. The thermometer now in use in 

 France, and through a great part of the conti- 

 nent of Europe, under the name of Reaumur's, 

 ought strictly to be called Mr. De Luc's, who 

 made a very important alteration in Mr. Reau^ 

 •mur's mode of graduating the instrument, and 

 again exchanged alcohol for mercury. In 1733 

 M. De L'Isle, of Petersburgh, constructed a mer- 

 curial thermometer on the principle of that form- 

 ed by Reaumur. This is generally used in Russia. 

 .Another, graduated in a different manner, by Cel- 

 sius, and also filled with mercury, is most popular 

 in Sweden.'^ 



Besides these leading inventions and revolutions 

 .which the history of thermometers presents, the 

 plans which have been suggested in modern times, 

 for improving this instrument, are many and in- 

 genious. These have been successively proposed 

 by Lord Cavendish in 1757; by Mr. Six in 1782; 

 by Dr. Rutherford in 1790; and still more re- 

 cently by Mr. Keith, whose new self -registering 



/ Sec Marti Ne's Essay on thermometers. 



