86 Prof. B. Stewart on Magnetic [Feb. 7, 



Table IV. — Spotted Solar Areas, Nine-Monthly Values. 







1853. 



1854. 



1855. 



1856. 



1857. 



January 



(2) 



475 



214 



170 



17 



87* 



February 



(2) 



AQCi 



1 73 

 i-l o 



1.00 



1 7 



X4 



101 



March 



(2) 



"±1 o 



1 4,1 



138 



io 



117 



-L-L / 



April 



(2) 



450 



126 



112 



21 



144 



May 



(2) 



438 



127 



83 



27 



182 



June 



(2) 



434 



131 



48 



26 



214 



July 



(2) 



425 



140 



20 



26 



235 



August 



(2) 



390 



147 



15 



32 



287 





353 



165 



15 



40 



350 



October 



(2) 



318 



191 



15 



44 



400 





283 



193 



16 



51 



450 





252 



182 



17 



70 



479 



6. The results of Tables III and IV are exhibited in the diagram 

 which accompanies this paper. 



In fig. 1 we have a curve representing the nine-monthly values of 

 spotted area. 



In fig. 2 we have the Kew and in fig. 3 the Trevandrum declina- 

 tion curve represented by nine-monthly values of the proportional 

 numbers. 



In fig. 4 we have a curve representing the mean between the pro- 

 portional numbers of Kew and those of Trevandrum. 



From these figures it will be seen that a lagging behind the sun 

 is a feature both of the Kew and the Trevandrum curves, while 

 generally the prominent points in the Kew and Trevandrum curves 

 agree well together in point of time. 



On the whole it would appear that by taking the mean of the pro- 

 portional numbers for the two stations, we get a curve that represents 

 the solar curve better than one derived from a single station. 



The whole period compared together represents both for the solar 

 curve (fig. 1) and the mean curve (fig. 4), a series of three smaller 

 periods, one extending from B to C and embracing the maximum ; 

 another extending from C to c, and a third from c to e ; and this is as 

 far as the observations common to both stations allow us to go in 

 point of time. 



7. It may be of interest to compare, by means of the tables, the period 

 between the solar minimum of 1855 and that of 1867, with the period 

 between the corresponding declination-range minima. The first of these 

 declination minima occurred at Trevandrum (the Kew observations 

 not having then begun) on February 15, 1856, and the second of 



* The numbers for the years 1858-64 are given in Proceedings of Eoyal Society, 

 March 22, 1877, page 109. 



