ON COMPARISON OF MAGNETIC INSTRUMENTS. 
97 
Comparison of Dip Circle No. 94 with the Instrument in use in the 
Valentia Observatory (Caherciveen). 
: Instru- | Position of . 
Date Time ment | Instrument Dip art tes 
We M. sage L 
s (V M.H. 68 39-7) : 
Aug. 28 16 57 is outside 39:2) +05 
- Vi outside 42°] : 
” 18:63 is MH. 386) +35 
(11 43 V é 41:9 
Aug. 29 37 | 8 3 41-0} +09 
(13 29 Vv if 41-9 18 
” 113 23 Ss _ 40-7} iT sky 
12 15 Vv x 425 ( 
Sept. 1 {4211 S 4 49-5} +00 
Mean +1'2 
Summary. 
The following is a summary of the results obtained at the different 
observatories :— 
— K-S r_-s =-S vV-s 
Declination —O'4 +04 —1"5 —O'4 
Horizontal Force —0-:00011 + 0:00007 —0:00005 —0:00040 
Dip. —0'6 +1"0 —2'8 +1"2 
By subtraction we eliminate the instruments used in the comparisons, 
and get the following relations among the instruments of the observatories : 
The three figures refer to declination, horizontal force, and dip—in 
order—the differences of H being expressed in terins of 0:00001 C.G.S. 
units. 
The table is to be read from left to right, thus :— 
The declination given by the Kew standard=that given by the 
Falmouth instrument — 08. 
— Kew | Falmouth Stony hurst | Valentia 
. { — —0'8 +11 0''0 
RCS Gat el Seis ale — | —18 —6 +29 
| ane dM +2"2 ~1'8 
| +0'8 | — +1'9 +0'8 
| Falmouth . . - | +18 —_ +12 +47 
{ +16 = +318 —0"2 
(| aay UE | | —1'9 a= ier 
Stonyhurst . : : | +6 —12 _ +35 
; —2"2 —3'8 — —4'0 
{| 00 -0'8 +1'1 — 
Valentia 5 4 —29 —47 —35 = 
| +1°8 +0°2 +40 = 
1896. Sheet ¢ H 
