96 A. M. Mayer—Effects of Magnetization 
of the induced currents formed on making and breaking the 
circuits in the various manners given in the following experi- 
ments. 
(1.) Made circuit in inner helix, rod elongated 1:4 division. 
oh 4c ““ outer 73 ti oe . ab 
Broke oe 4c “ec 
oe cc ag jnner oe 
(2.) Made circuit in outer helix, rod elongated 1°5 divisions. 
“i “ “inner ‘rod suddenly retracted “4 div., 
and then suddenly elongated ‘4 division. 
Broke circuit in inner helix, rod suddenly retracted °4 div., 
and then suddenly elongated -4 division. 
Broke circuit in outer helix, rod retracted 1:5 divisions. 
(3.) Made circuit in inner helix, rod elongated 1:4 divisions. 
oe “ 4c outer ing 4s “ ‘95 ae 
- “ retracted 25 “ 
ce ce 1-4 4¢ 
Broke circuit in inner helix, rod suddenly retracted ‘35 
division, then suddenly elongated ‘35 division. 
Broke circuit in outer helix, rod retracted 1°65 divisions. 
(4) Made circuit in outer helix, rod elongated 1°5 divisions. 
Made circuit in inner helix, rod suddenly retracted ‘5 divi- 
sion, then suddenly elongated -05 division. 
Broke circuit in outer helix, rod retracted 1 division. 
” “-toner- © * “14 divisions. 
On the times occupied in the elongations and retractions of a rod 
when the two component helices are joined as one helix, and 
placed in the circuit of one battery. 
The determinations I here give were made with the eye and 
a chronograph, and although not as accurate as the interest of 
the research demands, yet are near enough to the truth to show 
that the subject is worthy of a careful investigation. 
experiments given under the above heading and the succeeding 
one, give an insight into the velocities of the molecular motions, 
and therefore these determinations, taken in connection wi 
the measures of the corresponding elongations and retractions, 
will be of considerable theoretic interest, when they have been 
determined with the precision which the following proposed 
- apparatus will, in all probability, afford. 
I thus propose to attack this problem. The mirror of the ap- 
paratus will be made of the minimum weight consistent witl 
stability. The mirror will reflect a pencil of light from an elec- 
tric lamp to a revolving glass disc coated with sensitized collo- 
dion. This converging pencil will form a dot of light on the 
dise and when the latter is stationary will, on the elongation of 
the rod, describe a portion of one of its radii, which will appear 
on developing the sensitized plate. If, however, the disc have 
