f 416 ] 



LXir. Observations respecting a New Scale for (he Tlief^ 

 mometer. By Richard Walker, Esq, of Oxford. 



JL HERE are four different thermometers in use at this 

 lime, viz. Fahrenheit's, Reaumur's, Celsius's, and De 

 risle's. 



Fahrenheit's scale, which is used in Great Britain, has the 

 zero, or commencement of the scale, placed at 32 degrees be- 

 low the freezing point, and 2 1 2 is the boiling point of water* 



Reaumur's, or the French scale, modified by De Luc, in 

 which the is placed at the freezing point, and from thence 

 to the boiling point are 80 degrees*. 



Celsius's scale is used in Sweden; in this is placed at 

 the freezing point, and from thence to the boiling point 

 are 1 00 degrees. 



De risle's scale is used in Russia; in which is placed 

 at the boiling point of water, and the freezing point is 150. 



With respect to Fahrenheit's scale, it may be considered, 

 now, as having no foundation whatever in any principle, 

 and is in fact upon that account universally disapproved 

 of, and evidently upon (he decline. 



Reaumur's scale, and others in which the freezing point 

 of water has been adopted for placing the O, or com- 

 mencement of the scale, has been hitherto deemed the least 

 objectionable, on account of its being an invariably fixed 

 point. 



In the construction of thermometers two fixed points 

 are required : accordingly, the scales of all thermometers 

 have hitherto been, and probably ever will be, adjusted by- 

 means of the freezing and boiling points of water; the latter, 

 as is well krvown, being an equally fixed point with the 

 former, under certain circumstances well known to the 

 philosopher and the artist. 



The freezing and boiling points of water, then, may be 

 considered as applicable only to the due arrangement of 

 the proportions and precision of a thermometrical scale, 

 and consequently either of them unfit for the place of com- 

 mencement of it : hence the place where should be 

 placed is yet a desideratum. 



Considering the thermometer as a measure of heat, leav^ 

 ing the negative term cold out of the question, the pro- 



* A thermometer called the centigrade has lately been hitroduced in> 

 France, which is in fact uo other than that of Celsius,^ with the addition of 

 decimal divisions. 



per 



