112 ZL. A. Bauer— Variation of Terrestrial Magnetism. 
Tasie II.—Secular Variation. 
LARGEST SECULAR CHANGE BETWEEN 1780 AND 1885. 
In Declination. In Inclination. 
Latitude. Latitude. . 
Long. ° fo) ° ° ° ° ° ° ° Oe ne) ° ° ° * 
EB. of G.|+60 +40+20 0 —20 —40 —60/Mean) + 60+40+2uv 0 —20 —40 —60|Mean 
"0 «| 60 65-2 66 57 112 15°4 14°5| 9-2 | 3°5 8:0 18:0 23°717°2 T1 — |14°8 
20 65° 73 70 69 3°T 9:1 13°23) TU | 28°63 16:3 22-1919 0 ee 
40 72 8077 69 49 2°0 O46 (1-245) 62 1405S oe eee 
60 95 80 5°0 4:2 2:7. 2:5 812) S49 198sS. 454 O33) sb:0 eee eee 
80 93 16 3°7 (0 2:7 3°5 9:0) 52 | 3:2 4e3 1820 2S ee one 
100 5D 5-7 26 2:0 17 2:5 15's) S57) 7] 3°) 3:8 96-5) d¢b 5 eee eee 
120 23 -3°1 0:9.-1°9 -41 -5°6°18°9) 53-4 273 -2:4a5 182 Se ee eee 
140 65 71399 1:5 45 4:9° 75:22) i 2-9 7b eee eee 
160 istnien Aisi) 575 eae el ee A 70! Al | 2:1 45 538 333 27 
180 45. 4°93 8 «18 91:5. Ort (559) 256 | 9 4°83 © 3 
200 3°9) 4:7 2:3 19) Weke Oi) 26921 22°8) 1192.. 5 2 10 Sale 
220 3°30 1°% 3°0: 4°0 3:72 05°6. ) 9:91r4e4.| 57 453 © 9°8: SiO eee ee 
240 1% 4:3-3°8 4°]. 8:0 11-4. 1651) 7:9. |:1:2.-9°6.._ 6°99. 5G Sa Oe en 
260 18°6 5°7. 24 -352. T-Oel1°2. 11:0) 8:4... | 2°6.9°5. 3°45 Zee see 
280 17-8. 3°6 2°T .2°3 456 .5°9-. 3:0) 5:7. | .3°3°3°8 + 2:7 15-6 ee aele aes 
300 18°2 10°2 4°99 4°5 4:99 64 .6.6] 8:0 |.1:0°3°5, 2°6 5:1 0-3 lee 
320 13:5. 12:1. 9:0: 10:2 13°9..13°6 LO-O}L1:8 \:2:6 1°59. (350) 3403 Oe sleet 
340 T 2. 653) COND AdGSii | 13°3/11°3. | 3°3 6°0 10°8 12°1 6-9 ala AO 
Mean 86 57 4:3 493 5:4 6° 10°3| 6°5 |) 2:5 4:2 TA S064 eee 
Range |16°3 10°8 8°1 11°7 15°2 16°4 15°9/13°5 | 4°7 6:1 15-4 22-2 16°9 13°9 — |14°9 
Kaplanation of Table [—The first column gives the dates 
to which the various quantities apply. The next seven columns 
give the mean declinations along the parallels of latitude desig- 
nated at the top, as derived from 18 equidistant scalings (at 
every 20° longitude). It will be noticed that the quantities, 
though small, are invariably positive, i. e. there is a preponder- 
ance of westerly declination along every parallel. This has 
been found to be true also for other dates than given. It can 
be accepted then as a fact and must have a meaning. 
The ninth column contains the mean declinations of the 
seven parallels. In looking over the figures it will be noticed 
that they are nearly constant. Whether the slight variation is 
real and not due to imperfection in the data cannot as yet be 
ascertained. 
The following seven columns give the range or total change 
in declination encountered in going along a parallel of latitude. 
For example in 1780, in latitude 60° N. the maximum westerly 
declination (40:0) occurred in longitude 300° E. of Gr. and the 
maximum easterly (80°8) in 220° E., hence, a range of 70°:8 
* This column gives the mean values for the five parallels +40° to —40°. 
