Lifting Power of the Electro- Magnet. 

 Table V. 



513 



(13) 



giving 



L = 911-85 j 1 - i! . log-' (7-09736) + 1\ log' (5-08868) 

 -iMog-' (2-61666) |. 



Thirdly. With the cylinders = 101, with the helices (5), (/), (K), (L) 

 and {M), containing 1002 spires, and with ^= 55375, I obtained,* 



giving 



Table VI. 



L = 735-69 \l-t. log-' (7-30919) + e . log"' (5-40470) 

 -zMog-' (2-98826) j. 



(14) 



It must be remembered, that these equations are mere formulsB of interpo- 

 lation, and not the actual functions expressing the change due to temperature ; 

 yet there is an evident correspondence between them and the forces which are 



* As the slide was at the bottom of the magnet, the plan of heating it, used for the others, 

 was not availahile ; but by placing a brass curved funnel over a double argand gas-burner, a stream 

 of heated air was thrown within the covering of the magnet ; and by placing its orifice so that 

 part impinged on the slide, while the rest circulated within tlie confined space, 1 insured the same 

 temperature in the slide and cylinders. 



