1866.J Extract of Letter from Mr. Chambers, Bombay. 



113 



The Table of aggregate values of disturbance in the several years points 

 very distinctly to a minimum as occurring early in 1864, thus adding 

 another to the determinations of this turning-point in three former cycles 

 given by you in the third volume of the * St. Helena Observations/ and 

 confirming the conclusions you arrived at as to the propriety of the appel- 

 lation " decennial " to the period in question. The Table does not extend 

 far enough backwards to fix the time of maximum distinctly, but it suf- 

 fices to place it with probability in the year 1859. 



The principal requests that I have made in my Report are for a set 

 of Kew magnetographs, and for a suitable room, and for a body of com- 

 puters to work up the old observations. 



Astronomical hours. 



Ratios of the aggregate values of 

 the declination - disturbances 

 exceeding 1' '4 in amount at the 

 several hours in the seven 

 years from 1859 to 1865 in- 

 clusive. 



Bombay. 



Kew 

 (approximate). 



Westerly 

 disturbances. 



Easterly 

 disturbances. 



12 

 13 

 14 

 15 

 16 

 17 

 18 

 19 

 20 

 21 

 22 

 23 

 

 1 



8 

 9 

 10 

 11 

 12 

 13 

 14 

 15 

 % 

 17 

 18 

 19 

 20 

 21 

 22 

 23 

 

 1 

 2 

 3 

 4 

 5 

 6 



•05 

 •17 

 •16 

 •14 

 •18 

 •36 

 •80 

 •96 



1- 64 

 2^35 



2- 73 

 2-76 

 2-84 

 2-57 

 1-86 

 1-41 

 106 



•61 

 •40 

 •45 

 •16 

 •11 

 •16 

 •08 



•70 

 •68 

 •64 

 •84 

 •69 

 •71 

 •92 

 M7 

 1-00 

 1-08 

 1-61 

 1-83 

 1-68 

 1^56 

 1-29 

 •99 

 •91 

 •85 

 •85 

 •80 

 1-00 

 •79 

 •70 

 •72 



3 

 4 



5 

 6 

 7 

 8 

 9 

 10 

 11 



Aggregate values in the seven 

 years 



2801-1 



4538-7 



7339-8 



