48 On ihe Influence of the Almosphere on the Electric Coluinms 
period the whole apparatus has been inclosed together in @ 
glass case, where all experience the same atmospheric influence. 
As my columns are constructed similar to those already de- 
scribed in your Magazine, it will be unnecessary to describe them 
any further than to say that the diameter of the balls is 2°65 
inches, their distance from each other 0- 58, and the diameter of 
the gold ball 0:4 inches. I have constructed several other co- 
lumns of different diameters; and from a comparison of one 
which is only 0:53 of an inch in diameter with one whieh is 
0:76 of an inch (and by which this register is kept), | am in- 
clined to believe that the power of the instrument is very little 
increased by the diameter of the plates, but that it regularly in- 
creases with their number. But, as I am engaged in making 
other columns of different construction and diameter, [ shall 
soon be enabled to speak more decisively on this head. 
JOseillations 
Direc-| Vher- 
Date. {sion af haeee. B i Elyero: ina 
Wind. | ter. MIEPES MBSE minute. 
Dec. 1 Ss 55 29:90 380 268 . 
2 S Hye 30°15 81 248 
3 SE 51 30°10 79 240 
4 NW 51 29°85 69 222 
5 SW 44 300 68 210 
6 NW 45 29'5 66 200 
7 NW 43 29°85 71 200 
8| N | 31 |30:05| 60 | - 186 * 
9 N 290 30°10 61 168 
10 N 384 80 40 65 182 
11 N 36 80°40 63 188 
12 N 44 80°35 63 194 
13 | SW |. 43 | 30:30 | 65 194 
14 SW 45 80°35 59 192 
15 SW 47 29°90 61 206 
16 W 50 29°20 |. 60 224 
17 W 45 29:10 55 200 
18 W 42 29°46 55 186 
In the | 
Galleryof} 
Lecture- 
Room. 56 | 29°50.| ‘50 284 
19 W 42 29:60 54 186 
20 45 29°40 56 200 
21 
I am, sir, 
Be Yours, . 
Darset-street, Salisbury-square, J. Tatum. 
Dec. 21, 1815. 
a 
XIII, De- 
