202 A. D. Bache on Declinometer Observations. 
cycle, and arriving at its eastern elongation aneety before 8 a. M. 
gee nocturnal deviation is well marked in winter, vanishes in 
oak the 
that if if Fhe effect of disturbances was completely obliterated in 
the results, this small cugican would disappear. In summer 
when it is not noticed the needle remains near! y stationary from 
8p.M.to3a.M. The ie curves for the year, show a similar 
result. The diurnal curves for the months when the sun’s decli- 
nation is north, = those when. it is ne. resemble each other 
closely, as is shown by diagrams D and E. 
For greater peteisien in regard to the epoch and amount of the 
diurnal variation we must recur to the analytical expressions 
representing the numbers of the table. 
he following table contains the results for each month and 
for the summer and winter seasons and the whole year, also the 
critical interval between the two adjacent hours of the mean po- 
sitions. 
stical ¢ Epoch of mean oo 
OE ne ae ge ee 
: Ps ae M.- 2. min. to ma A.M EM) eee 
58 1s 429 10 52 7 08 8 16 
$4 1 32 458 10 52 4 26 8 34 
07 1 34 5 27 10 46 4 35 8 46 
12 1s 15 10 34 7 40 8 56 
29 12 5 bY 10 19 6 57 § 38 
33 1 20 547 10 25 8 26 10 01 
36 1 238 5 52 10 80 9 32 11 02 
18 1 05 B47 10 10 8 40 10 30 
30 0 45 5 15 9 58 6 45 8 47 
00 11% 517 10 30 5 23 6 53 
54 1 O§ 5 14 10 16 6 08 7 62 
54 140 4 46 10 50 617 Lae 
33 1 08 B35 1017 7 43 9 26 
24 125 5 O01 10 40 6 49 8 09 
48 116 5 28 10 26 7 08 3.42 
The formule also give for the time of the seondary minimum 
of tore declination in winter 9h 42m p. wr. and for its amount 
For the time of the secondary maximum of western declina- 
tion in winter, 18 15™ 4. w., and for its amount —0'26; differ- 
ences 35 33™ and O”71. 
For the secondary minimum of eastern deflection for the year: 
104 11™ p. m. and its amount, —0”62. ; 
For the secondary maximum of western deflection for the 
year, 12 13, and its amount —0°47; differences 34 02™ and 0’ 15. 
in the foregoing table, the eastern elongation occurring earliest 
the summer solstices and the autumnal equinox, 
latest about the winter solstice. 
