159 



Oba. 

 For 1850, mean epoch — 



mean of May 22, 70°„ 17*24 (8) 



mean of June 27, 70 17 35 (6) 



mean of July 6, 70 15 (5) 



General mean, June 14 70 15 63 (19) 



For 1851, April 29 70 18 95 (1) 



For 1853, Aug. 2 70 10 1 (2) 



The mean epoch of the whole period is Feb. 3, 1842, and the mean 

 dip of the period 70«> 37'3. 



The early period including 1837, 1838 and 1839, will be represented 

 by a mean epoch of 1838, Jan. 27, and a mean dip of 70 47 9 

 The late period 1850 to 1853, will be represented by a mean 

 epoch of 1850, Oct. 27, and a mean dip of 70 15 4. 



\^ 



The straight line a h drawn in the diagram represents the 

 result of this computation. It passes through the three cal- 

 culated mean points, and near to all the others, and indicates an 

 annual diminution of the dip of 2'*54, a result only a little 

 different from that found between 1821 and 1838, by Col. Sabine 

 for Britain, and by Dr. Lloyd between 1833 and 1836 for 

 Ireland. The remarkably low observations of 1846, and the 



