202 



PROFESSOR FORBES ON THE TEMPERTAURE OP THE EARTH. 



at freezing for 1°. cent.,* or -000555 for 1° Fahr., a quantity one-tenth greater than 

 its mean dilatation usually adopted. I accordingly had a Table constructed on 

 tliis basis, with a double entry, one for the number of degrees, or space in the 

 tube filled with the expanded liquid, and the other for the excess of temperature to 

 which it is exposed. The arguments used for the two corrections, with this Table, 

 were the following : — 



2d Argument. 



Degrees of Temperature 



to be corrected for 



7a + 3 b + c 



Ist ArgUDient. 



Capacity in Degrees 



to be corrected. 



\st Correction (for Temperature of Stem), Table, p. 198. 



Id Correction (for Temperature of Air), 



T-h 



T-«: 



The sign of the correction is always opposite to that of the second argument. 



* Fechner's Repertorium, II. 430. The expansion of absolute alcohol is somewhat greater as 

 given by Muncke, in a paper in the Petersburg Transactions, read 5th September 1834. 



