A. D. Bache on Magnetical Observations in Maine. 145 
- declination to its av erage value of the day. The minutes given 
in the table are to be added to 17°. 
is | tee2” | teed” | eat | Means 
’ ‘ 4 i 
ug., 581 595 60'1 642 605 
Sept., 569 611 611 63 6 60-7 
Oct., 57-2 60-1 60°8 63-7 605 
Nov., 598 61-7 63:5 643 62:3 
Dec., 585 59°2 623 627 60°6 
an., 565 61-0 621 62:8 606 
April, 58-7 612 62-0 63-0 61:2 
f 80 60°71 611 616 60°2 
June, 61-0 59:3 60-7 61-2 605 
July, 58°] 59-2 607 62:0 60:0 
Meuns, 58 2 601 61-4 62'9 60 65 
The average value for the period is 18° 00’-65. 
Annual effect of the secular change-—We deduce the annual 
effect of the secular change directly from the preceding table. 
Sonal increase of eter gerne between 1861 and 1862, 1"9 
18 es 
“ i “ 1868 “ 1864, © 1°5 
Average annual increase of west declination, 
which, considering the locality, appears a remarkably srhall 
value. Acc ording to our previous information we might have 
cted an annual increase of about 4. Either the above 
obtain a ponfignaG ion of its s scald Sorta increase; from four 
days of observation 18° 04"7 was found, and since ’ the annual 
mean is found by adding 14 (vide previous years) the declina- 
tion for 1865 becomes 18° 06’-1, and the annual increase appar- 
ently eqnrals 2’4 
e annual mean declination corrected for a number 
of observations in,1860 and 1864, is as follow 
In 1860, 17° 57°11 W. In 1863, ‘a 02"3 W. 
“1861” “it os - 1504, 18° )3'-7 = 
a Pe 18° 006 “ . ape 18° 0671 « 
beaten: Saal afalidation of this ties in refobelie to 
hich ey go oast Survey Report for 1860, pp. 811-12, may bs 
