450 Professor Forbes's Researches on Heat. 



may continue to exist in one direction, even after the wire has 

 been transmitting a powerful current in the opposite one. We 

 have not now time to dwell upon the peculiarities of the instru- 

 ment. I content myself, therefore, with stating, that I obtained 

 satisfactory results after several patient trials, and obtained the 

 following table of reduction to true degrees, or uniform measures 

 of heating effect, by projecting my results, and drawing through 

 them an interpolating curve. 



Table for reducing Galvanometer Readings to Degrees of uniform 



value. 



Reading. Corresponding Intensity. 



0.0 



0.0 



2.0 



2.1 



4.0 



4.2 



6.0 



6.3 



8.0 



8.6 



10.0 



10.8 



12.0 



13.0 



14.0 



15.4 



16.0 



17-8 



18.0 20.0 



20.0 22.4 



The measures in the first column refer to the stationary de- 

 viation of the needle of the galvanometer by the influence of any 

 heating cause. The result is remarkably uniform ; the curve from 

 which these numbers are derived, not differing very materially 

 from a straight line. 



8. Another mode of estimating the indications of the instru- 

 ment has been used by M. Melloni, and it is one particularly 

 adapted to our researches. It likewise gives much more uniform 

 results than might have been anticipated. Instead of noting the 

 final ox stationary deviation due to any heating cause, it is sufficient 

 if we note the arc through which the needle is first impelled, and 



