NIPHER MAGNETIC OBSERVATIONS IN MISSOURI, 1878. 89 



Magnet laid on table on cotton batting, and room allowed to 

 cool gradually by shutting ofT heat and opening windows more 

 and more ; finally put in bath as before, at ah. 05m. p.m. 



Scale before deflection Si.o 

 " after " i57-i ^t 2h, o8m. 



TEMPERATURE OF ROOM 65°. 



Results and Computation. 



Calling s =3 scale value of C^j ; 



u =z deflection at the lower temperature 



to (= 76^33, 

 = 3° 40' 6); 



/ =. length of I' in units of radius; 



d =^ change in deflection of C^^ for change of 



temperature of 

 t _ /q (=44°. 8) ; then 



C s. d. I. cot u ) 



