A. D. Bache on Declinometer Observations. 39 
representing a single value within + 0’11, the month of May, 
1843, is indicated as the epoch of minimum amplitude. 
The discussion of the disturbances, as far as they bear on the 
= inequality, next follows, taking in also some collateral 
results, 
The total number of observations for changes of declination 
recorded and discussed amount to 24,566; of these, according 
to the preceding investigation, 2,857 were separated as disturb- 
ances. ‘T'here’is one disturbed observation in every 10:4 obser- 
vations, The discussion.of the disturbances is divided into two 
quality in the distribution of the disturbances has been made 
out for each year, and the means and ratios are also given. The 
principal maximum occurs in October (at Toronto in September), 
the secondary in April; the two minima, nearly equal in amount, 
Occur in February and June (the first one in January at Toronto). 
The ratios of the number of monthly disturbances to the aver- 
age number are given in the following table, showing the same 
also divided into westerly and easterly values. 
RATIOS. RATIOS, 
E. Total Ww. _Total. 
January, | 127 | 042 | 077 | duly, 058 |118 |086 
February, 0-70 | 046 | 052m |August, |200M/114 | 159M 
arch, 083 | 057 | 068 September, | 0°93. | 1:86 | 1°36 
il, 0-95 | 0°80 | 091M, | October, | 1°58 | 250M) 212M 
MA 055 | 060 | 058 — | November,|/0°96 |1:12 | 1:08 
June, 0-44 | 0-61 | 053m | December, | 1°21 074 | 1:00 
Mean, [1°00 (100 [100 | 
b Wires ee eee 
1840 | 483 | weight 4 , 
539 end 
Proportional number of western disturbance 937, of east 
446 ; 
1843 | 275 weight $+ ern 912; at Toronto the eastern predominate over the 
808 western in the proportion of 1°17 to 1. 
| 1845 | 264 | weight 4 
_ These numbers do not indicate the law of the eleven year pe- 
tiod as plainly and systematically as found by the investigation 
