510 
DR. Gr. NEUMAYER ON THE LUNAR-DIURNAL VARIATION 
we must remember that during both periods the same instruments were used ; but still 
we perceive that towards the end of the latter period the abnormities above pointed out 
make themselves clearly manifest, even in the yearly curve with the moon’s declination 
north and south (see Plate XIX.). This seems to speak strongly in favour of a pro- 
gressive change rather than of an accidental irregularity. It would be premature to 
enter upon an explanation of these facts at present, as it is evident that for such a 
purpose we are in need of similar discussions from other localities ; suffice it to call 
attention to so important a class of phenomena. The subjoined Table shows the results 
of this last-mentioned inquiry, and on Plate XIX. are found the lunar-diurnal variation 
curves for the periods above delineated. 
Table III. — Lunar-diurnal Variation of the Magnetic Declination for the periods May 
1858 to April 1859, and May 1860 to April 1861. 
1st. From the superior to the inferior passage. 
Declination of the 
May 
Lunar hours. 
Sun. 
Moon. 
to 
April. 
0. 
i. 
2. 
3. 
4. 
5. 
6. 
7. 
8. 
9. 
10. 
11. 
S. and N. 
S. andN. 
rise 
+12-18 
+13-37 
+ 9-61 
- 0-31 
- 4-98 
- 0-14 
- 8-48 
- 12-63 
- 2-15 
+ 3-82 
+ 5-84 
+ 3-29 
1 18ff 
+ 4-16 
+ 4-57 
+ 8-85 
+ 4-48 
- 1-35 
- 2-89 
-10-30 
- 2-38 
- 5 98 
- 5-24 
+ 3-45 
+ 13-55 
S. 
f 18ft 
4- 5-47 
+ 9 00 
+ 9-24 
- 6 95 
-12 02 
- 2-29 
-1175 
-16 39 
- 7 90 
+ 0-55 
- 1-39 
- 4-52 
” 
+ 7-43 
+ 5-44 
+ 10-96 
+ 8-48 
- 1-85 
+ 2-05 
- 9-56 
+ 2-35 
- 7-87 
+ 0-20 
+ 4-49 
+ 11-63 
N. 
nm 
+20*3o 
+ 18-73 
+ 1005 
+ 7-52 
+ 3-64 
+ 2-46 
- 4-78 
- 8-42 
+ 5-20 
+ 7-96 
+ 14-83 
+12-41 
118« 
+ 0 96 
+ 3-73 
+ 6-73 
+ 0-28 
- 0-82 
- 8-21 
— 11-08 
- 7-40 
- 3 95 
— 11-05 
+ 2-30 
+ 15-63 
2nd. From the inferior to the superior passage. 
Declination of the 
May 
to 
April. 
Lunar hours. 
Sun. 
Moon. 
12. 
13. ! 14. 
15. 
16. 
17. 
18. 
19. 
20. 
21. 
22. 
23. 
S. and N. 
S. and N. 
S. 
N. 
1 
1 
’ 
L lip 
[11 
+ 7-96 
+ 9-72 
+ 0-93 
+ 6-55 
+ 16-43 
+ 1313 
+ 1-91 
+ 4-22 
- 9-60 
- 2 03 
+ 16-40 
+ 1111 
- 6-94 
+ 2-26 
- 3-69 
- 7-21 
-10-75 
+ 12-43 
- 4-36 
+ 3-65 
+ 1-29 
- 2-51 
-10-83 
+ 10-38 
- 12-90 
- 2-41 
- 9-57 
-16-88 
- 0-98 
- 6-81 
- 8-83 
- 4-46 
-13-38 
- 9 55 
- 4 04 
- 5-44 
- 4-73 
- 2-78 
-10-58 
- 8-41 
+ 1-64 
- 2-93 
- 6-67 
+ 1-66 
-10-36 
- 8-24 
- 2-89 
- 5-27 
- 6-09 
- 9-53 
- 11-12 
— 0 32 
- 0-91 
- 107 
- 4-66 
- 7-30 
- 6-87 
+ 608 
- 2-42 
+ 7-85 
+ 706 
- 2 03 
+ 7-21 
+ 19-60 
+ 6-91 
+10-89 
+ 5-79 
+ 4-00 
+ 6-96 
+ 19-51 
+ 4-60 
On Plate XIX. we represent furthermore the two annual curves of the same periods 
without reference to the moon’s declination, and we perceive that there is a depression 
in the curve for 1860-61 near the moon’s upper transit, as likewise an increase of 
easterly declination near her inferior passage, while the curve for 1858-59 bears more 
the character of the mean curves for five years. 
These few facts may for the present suffice to induce those who are engaged in similar 
pursuits to enter upon such a laborious task as is the classification of magnetic observa- 
tions for the purpose of examining into the law and nature of the lunar-diurnal variation, 
according to the moon’s position north or south of the equator. We may, however, 
rest assured that such inquiries will ultimately prove to be conducive of the greatest 
