ON COMPARISON OF MAGNETIC INSTRUMENTS. 93 
Comparison of Magnetometer No. 70 with the Instrument used in the 
Falmouth Observatory. Horizontal Force. 
Instrument = (he Kg 
Date Time and H Curve ween. Pe 8 x10" | é Sai 
Observation A 
iN | | 
H. M. | 
Aug. 6] 10 56 FV = 0718572 _— —_ _ +0'00003 
a 12 43 FD 0718545 018569 0718571 —26 
cA 13 24 FD 0°18537 | 0718560 0°18566 —29 | 
i 11 24 F zh 0718578 ) 
Pe 12 0 FD 0718554 0°18578 | 0°18578 (—44] 
5 15 22 8 bt 0°18594 ) 
- 16 22 sD 0°18555 0°18578; | 0°18586 _ —31 
Aug. 7 10 44 EF bf 0718519 0718541 ) 0718542 —23 
Fe 11 32 FD 0718543 f } 6 
a 12 27 s ut 0°18520 | 018549) | 0°18549 —_ —29 
ss 13 15 sD 018549 } 
Aug. 8 he 3% FV } 0718521 0718542 } 0718545 —24 
© 11 49 FD 0718548 13 
i 12 50 iS) ai 0°18523 0°18564 ) 0°18565 - -37 
4 13 34 sD 0°18566 J 
Aug. 9 10 45 F a 0°18536 018558 ) 018553 -17 
‘J aay FD 0°18548 j | 9 
os ll 44 Ss yi 0718529 | 0°18555) | 018557 —- —28 
As 12 50 sD 0718559 | | 
Aug. 10} 10 55 FV 018468 | 0°18490) | 0718492 —24 
x 11 43 Fr p} 018494 f | 6 
ea 12 50 SV 018487 | 0718514) | 018517 — —30 
as 13 31 Ss p} 0°18521 
Aug. 12} 10 53 FV 0°18500 | 0°18519) | 0°18525 —25 
a 11 37 F p} 0718530} | 5 
- 12 50 Sv) 0°18520 | 0718548) | 018550 _ —30 
33 13 31 8s Dj) 0718552 ) | 
ee | | | 
Mean . _ _ _ = SS _ =_ +0:00007 
Comparison of Dip Circle No. 94 with the Instrument in use in the 
Falmouth Observatory. 
Date Time Instrument Dip | F—S=B 
H. M, | Cinipal f 
August6 . . 17 32 | S 66 588 Bins 
iS = 7 18 46 } F 66 58-0 
August 7 . 0 16 14 5 66 57:1 ae 
” : 2 14 38 | EF 66 58°6 
August 9. ; 15 25 iS) 66 57°8 417 
” : e 15 28 | F 66 59°5 
é pei v.- 17 35 Ss 66 545 
; cae 17 35 F 66 aaa! +19 
August 10. ‘ 15 27 ) 67 0-6 : 
‘ pasa | 15 24 F 67 ed +05 
August i2 . A 15 32 iS) 66 59°8 +403 
, bog eee 15 28 Fr 67 O1 
5 16 17 S 66 59:0 
4 16 42 F 67 ast U8 
Mean : c ; ¢ 5 - : 7 3 - | +1:0 
The curves used were those obtained from the self-recording instruments 
in use in the Observatory ; but as the vertical force instrument was not 
working well the dip circles were directly compared with each other, as in 
the first method used at Kew. Each of the dips given in the above 
table is the mean of the two observations, one of which was made with 
each of the two needles employed with the instruments. The individual 
