Ixxiv General Results or the Makerstoun Observations. 
these remarks may be kept in view, in considering the numbers in the following Table, which are obtained from 
Plate VIII. 
Table 68. — Angular Distances between the Disturbed and Undisturbed Positions for each Hour in the 
motion of a freely-suspended Dipping-Needle, as obtained from Plate VIII. 
Mak. 
Dec. 
ibept. 
Sept. 
March 
Year. 
March. 
May. 
June. 
July. 
Aug. 
Jcin . 
Oct. 
to 
to 
Prom 
Mean 
Time. 
Feb. 
April. 
Nov. 
Feb. 
Aug. 
Mean 
of first 5 
Curve. 
Columns. 
h. 
12 
U-JO 
U-20 
A O /I 
0-34 
A OO 
0^2o 
A O C! 
0-3d 
0-35 
A O E 
0-2o 
0.^9 
1 o 
•ZD 
•o2 
O^J 
•2o 
0/1 
•24 
oo 
•2o 
OQ 
•2o 
■31 
.96 
.27 
14 
•z8 
•4o 
OA 
•20 
1 o 
•lo 
•14 
1 o 
• lo 
oo 
•2o 
.94 
.94 
15 
•09 
•Id 
• J.O 
•Oo 
1 o 
•12 
AO 
•Oo 
1 o 
• 1 2 
• 08 
•12 
16 
•Ofa 
A A 
•04 
1 Q 
•lo 
AO 
•Oo 
1 o 
•12 
A A 
■09 
•09 
.04 
17 
•15 
AO 
•u» 
AQ 
•Uo 
0/1 
•24 
1 A 
•14 
•VO 
1 A 
•14 
•08 
•14 
18 
•21 
OA 
•20 
AO 
•Oo 
•62. 
•34 
o c: 
• 2d 
1 o 
•lo 
• 22 
•24 
19 
•20 
•24 
1 A 
• 14 
•o2 
A A 
•40 
OA 
■29 
oo 
■22 
• 26 
• 27 
20 
1 o 
*J A 
•30 
O A 
•oU 
•4o 
A O 
•42 
OA 
•29 
O A 
■34 
•28 
•33 
21 
•22 
•OD 
OQ 
•2o 
Q A 
/I A 
•40 
on 
•oO 
o o 
•6Z 
•32 
•31 
22 
•24 
•28 
•26 
•20 
•26 
•28 
• 22 
•28 
•25 
2.3 
•24 
•30 
• 16 
•36 
•26 
•24 
•18 
•24 
•26 
0 
•28 
•28 
•12 
•14 
•.30 
•26 
•18 
• 22 
•23 
1 
•35 
•24 
•28 
•16 
•24 
•28 
•24 
•28 
•26 
2 
•36 
•36 
•40 
•16 
•38 
•34 
• 30 
•34 
•34 
3 
•29 
•32 
•26 
•24 
•36 
•30 
•28 
• 28 
•30 
4 
•28 
•44 
•46 
•44 
•16 
•40 
•44 
■32 
•33 
5 
•12 
•30 
•34 
•50 
•12 
•04 
• 35 
•18 
•26 
6 
•15 
•36 
•30 
•42 
•32 
•19 
•28 
•16 
•30 
7 
•18 
•42 
•30 
•26 
•38 
•27 
•22 
•24 
•30 
8 
•43 
•36 
•16 
•24 
•58 
•50 
• 24 
•38 
■38 
9 
•38 
•38 
•24 
•44 
•44 
•38 
•34 
• 38 
•38 
10 
•39 
•38 
•30 
•36 
■52 
•45 
•34 
■40 
•40 
11 
•42 
•26 
• 38 
•22 
•50 
•45 
•32 
•38 
•37 
166. The following are the conclusions from Table 68 : — 
l.s-t, In the two figures for the months from September to February, the effect of disturbance in displacing 
the needle is a minimum about 4'' a.m. and 4'^ p.m., the values for these hours being neai'ly equal, or near the 
hours when the sun is on the magnetic prime vertical. The maximum effect of disturbance occurs in both about 
lO** P.M., when the sun is on the magnetic meridian, a secondary maximum occurring in the figure December to 
February about l-g-^ p.m., and in the figui'e September to November about 8'* a.m. 
2d, In the figure for March-April, the minimum occurs about 4'' a.m., and the maximum probably about 
gh-lQi' P.M., the value, however, varying little for the 18 hours from 8^^ a.m. till 2^^ a.m. 
3d, The mean of the two results for the figures May-.Tune and July-August is to some extent the reverse 
of the result for December to February. The effect of disturbance is a minimum about 4'^ a.m., and about 
noon ; it is a maximum about 8'^ a.m. and 4"^ p.m. It would appear, therefore, that the diurnal law of the 
effect of disturbance varies with season as well as the law of the amount of disturbance (see Nos. 45, 77, 110) : 
a minimum is also shewn about 8>' p.m. 
ith, In all months of the year the eftcct of disturbance is a minimum about 4'^ a.m. In the winter months 
a minimum occurs at 4'^ p.m., the maximum occurs at the same hour in the summer months. 
bth, In the mean figure for tlic year, minima occur at 4'' a.m. and about 5,V' p.m., the maximum occurs about 
10'' P.M., and a maximum occurs between 8'' a.m. and 4'' p.m. If, making allowance for the effect of dis- 
turbance on the position of the centre of gravity with reference to dip (No. 1'21), we suppose the centre of 
gravity of the dotted figure for the year (Plate VIII.) raised 0'-15 on the line of moan declination, or that of 
the continuous figures lowered as much, we find the maxinuun effect of disturbance to occur about 10'' p.m. 
and 10'' A.M., and the niiuimum efl'oct about 4'' a.m. and o'' p.m. This result was obtained for tlie magnetic de- 
clination in 1844. See the Volume for that year, p. 345. 
