194 On the Revolution of the Seasons. [March, 



tion took place in 56 years, or three cycles. In pursuance of this idea 

 it was intended to described the first 56 years, beginning with 1835, 

 and then to place in a line above them the next 56 years beginning 

 with 1779 — so that their parallelism, or the contrary, might be more 

 easily detected. This has been done (see below) for the first 21 years 

 of each period, viz. from 1835 to 1815 both inclusive, and from 1779 

 to 1759, both inclusive ; and it will, I think, hardly be denied that some 

 degree of parallelism does exist between them. In the 35 last years of 

 each period, from 1815 to 1780, and from 1759 to 1723 the irregula- 

 rities were too great to allow their being placed in a similar manner. — 

 But 1 have traced out the variations from 1815 to 1780 (see the thin 

 continuous line in the plate from 1815 to 1780), and it will be observed 

 that the principal maxima run thus, 1815, 1806, 1796, 1787. 



Now we must consider that it is only by taking an average of differ- 

 ent cycles that we can get rid of the effect of such disturbing causes as 

 are only temporary — say, for instance, the inroad of an army, or the 

 decrease of the population. The average therefore of the four cycles 

 1815 to 1796, 1796 to 1779, 1759 to 1741, and 1741 to 1723, was 

 taken, and this average is represented by the dotted line from 1815 to 

 1796, and from 1796 to 1779. It appears to be nearly regular, and 

 probably succeeding observations may enable us to make it more cor- 

 rect. The dotted line from 1815 to 1835 represents the average of the 

 two periods, 1815 to 1835, and 1759 to 1779. 



Since writing my last paper I have also received a list of corn prices 

 from the Cape of Good Hope from 1835 to 1812, and another from 

 Bickanir in the desert for the same period. These prices have been 

 added to those of Dundwala in the Panjdb for the same years and from 

 the average a line has been traced similar to that of fig. 2, Plate, 

 (Journal, No. 64.) 



This long and tedious investigation was entered into in the hope that 

 certain useful results might be obtained, and the results that have been 

 obtained do make it highly probable that there is a certain degree of 

 regularity in the revolution of the seasons. If the number of rain- 

 gauges in different parts of the country should be greatly increased, 

 and the prices of corn accurately registered, may we not hope that 

 something more definite may be established, even so far as to enable us 

 to fix the variation which may be due to each particular locality. Nay 

 more, if certain combinations of light, heat, and moisture be conditions 

 essential to every kind of animal and vegetable existence, may we not 

 conjecture that other productions than corn are affected by peculiar 





