200 



PROFESSOR FORBES'S RESEARCHES ON HEAT. 



Dark Hot Brass. March 31. 1838. 



Measure of 

 Diagonal a b, 

 Plate xiii. Fig. 1, 

 in Inches. 



Galvanometer-Needle 



Excess. 



Ratio to Result 

 with Diagonal 

 = 14.5. 



Stands at 



Swings to 



14.5 

 15.0 

 15.25 

 15.5 



16.75 

 16.0 

 16.25 

 16.6 



A0.°1 

 0.0 

 0.15 

 0.15 

 0.3 

 0.25 

 0.15 

 0.2 

 0.15 



All!o 

 9.3 

 8.0 

 6.2 

 6.3 

 4.6 

 3.15 

 2.25 

 1.9 



10'.9 

 9.3 

 7.85 

 6.051 

 6.0 ) 

 4.36 

 3,0 

 2.05 

 1.75 



100 : 100 

 85 : 100 



72 : 100 



56 : 100 



40 : 100 

 28 : 100 

 19 : 100 

 16: 100 



14.6 



0.05 



10.8 



10.75 



Incandescent Platinum. February 10. 1838. 



Measure of 

 Diagonal a b. 

 Platexiii. Fig. 1, 

 in Inches. 



Galvanometer-Needle 



Excess. 



Ratio to Result 

 with Diagonal 

 = 14.5. 



Stands at 



Swings to 



14.0 



14.5 



15.0 



15.26 



15.5 



15.75 



16.0 



16.26 



16.5 



16.75 



B 0.°26 

 A 0.05 

 B0.15 

 0.0 

 0.1 

 0.1 

 0.1 

 0.0 

 0.15 

 0.0 



A 15!25 



15.6 



13.66 



11.76 



8.8 



6.1 



4.05 



3.3 



2.5 



2.25 



15°.6 



16.46 

 13.8 

 11.75 

 8.9 

 6.2 

 4.15 

 3.3 

 2.66 

 2.25 



100 : 100 

 100 : 100 

 89 : 100 

 75 : 100 

 68 : 100 

 40 : 100 

 27 . 100 

 21 : 100 

 17 : 100 

 15 : 100 



14.0 



0.9 



1.25 



1.7 



14.4 



13.76 



13.75 



15.3 

 15.0 

 15.45 



Heat from Locatelli Lamp sifted by a plate of Alum. March 31. 1838. 



Diagonal. 



Dynamical Effects. 



Mean Effect. 



Ratio to 14.5. 



Direct Series. 



Reversed Series. 



14.5 



15.0 



15.26 



16.5 



15.75 



16.0 



16.25 



16.5 



17.0 



3°.l 



2.96 



2.9 



2.15 „ 



1.76 1.7 



1.2 



0.8 



0.75 0.76 



0.55 



3.°2 3.°25 



2.9 



2.65 2.5 2.7 



2.1 



1.75 



1.26 



0.6 0.6 



0.7 



3.°18 

 2.92 

 2.69 

 2.12 

 1.73 

 1.22 

 0.67 

 0.73 

 0.55 



100 : 100 

 91 : 100 

 84 : 100 

 66 : 100 

 54 : 100 

 38 : 100 

 21 : 100 

 23 : 100 

 17: 100 



averages and ratios taken, generally on the same day on which they were made. This methodical plan 

 cannot be too strongly recommended. Much after anxiety is spared, the calculations are lightened, 

 errors avoided in the reduction after minute circumstances have been forgotten, and suggestions are 

 afforded by the result of past experiments for the conduct of new ones. 



