22 Mr Harris on Magnetic Intensity by the 
TABLE III. 
Oscillations taken in Shade, Temperature 62°. Oscillations taken in Sunshine, Temperature 70°. 
Time of ||_. Time of 
Vib. /Are. Time. |Vib.|Arc.| Time. | 100 Vib. })Vib.{Arc.| Time. |Vib.JArc.) Time. | 100 Vib. 
2 4 |100) 4 | 13 54.5)11 50.5 
3 14.5) 10 15 5 {11 50.5 
4 25.2! 20 16 16 |11 50.8 
5 36.5) 30 17 27.5)11 51 
6 47.5| 40 18 38.5) 11 51 
7 58.5} 50)3.5|19 49.5) 11 51 
° 4 a“ ‘ 
0| 5 |24 4 |100) 4 [35 53.5) 11 
10 25 14.5) 10 37 AL 
20 26 25.5) 20) 38 15 |11 
30 27 36.5) 30) 39 26 | 11 
40 28 47 | 40 40 36.5] 11 
50 29 58 as Al 47.5) 11 
—_—| ———| 
60 31 9 11 
9° 95 304,8 
10 21.5|Mean of 100 Vib.| 11 50.8 
11 32.2)/Time of 150 Vib.|17 45.5 
12 43.3/Term. are, one. 
70 32 20 |Time of 100 Vib.| 11 
80 33 31.5/Time of 150 \ ib.) 17 
90 34 42.5'Term are, 
Although the differences in time, in the above Table, in the 
shade and in sunshine, are somewhat small, and might not be 
considered, upon an insulated series of experiments, of great im- 
portance ; yet the constancy of the result, on repeating the expe- 
riments for many successive days, together with the general 
agreement with the phenomena in Table I, and the great suscep- 
tibility of the bar in indicating such differences when oscillat- 
ing in a void and in small arcs, are considerations which claim 
for these researches some degree of confidence. 
36. With a view of examining, in some measure, the accu- 
racy of the preceding deductions, I resorted to the following ex- 
periments :— 
(e) A bar of copper, of the same dimensions as the magnetic 
bar above described, was made to vibrate under a closed receiver 
in air and in a void, and the vibrations, arcs, and times noted, as 
before (Table II), both in the sunshine and in the shade : the vi- 
