136 



THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



mum sun-spots since the returns began in 1813. 

 This deficiency is well-marked, not only in the 

 years of minimum sun-spots, but in the years 

 preceding and following them. Thus, even in- 

 eluding the month of May and the exceptional 

 rain-storm of May, 1843, the southern monsoon 

 during the six years of minimum sun-spots, and 

 the years immediately preceding them, yielded, 

 during the twelve years thus made up, 20£ per 

 cent, less rain than its average yield in the sixty- 

 four years. Or, expressed in another form, the 

 water-supply brought to Madras by the southern 

 monsoon is 2G L per cent, greater in ordinary 

 years than in the years of minimum sun-spots and 

 those immediately preceding them. 



The two monsoons are the great factors of the 

 rain-supply at Madras, and their fluctuations are 

 distinctly marked in the third element of com- 

 parison, the total rainfall for the year. In five 

 out of the six years of minimum sun-spots the 

 annual rainfall fell short for the average supply, 

 calculated over the sixty-four years. The excep- 

 tional year was 1843, and its exceptional charac- 

 ter was due to the sporadic rain-storm in May, al- 

 ready mentioned. Even including that rain-storm, 

 however, the six years of minimum sun-spots had 

 an average rainfall of less than 34£ inches, against 



the ordinary annual rainfall of 4S£ calculated over 

 the sixty-four years. The minimum years of sun- 

 spots, therefore, brought 29 per cent, less rain- 

 fall than ordinary years: or, put into another 

 form, the average annual rainfall supply at Ma- 

 dras is 40£ per cent, greater than in years of 

 minimum sun-spots. 



In each of the three elements of comparison, 

 the deficient rainfall is not confined to the mini- 

 mum year of sun-spots, but includes the preced- 

 ing year as well. But it should be clearly stated 

 that no numerical proportion exists between the 

 actual number of sun-spots and the number of 

 inches. There is a rain-cycle of eleven years at 

 Madias, which coincides with the cycle of sun- 

 spots. The periods of maxima and minima in 

 these two cycles disclose a striking coincidence. 

 That coincidence is common to all the three 

 elements of comparison : namely, the rainfall of 

 the year, of the great northern monsoon, and of 

 the southwestern monsoon. The following table 

 will show this. • The cycle of eleven years starts 

 from 1876, and runs back to 1813, at which year 

 the rain-returns commence. The eleventh, first, 

 and second series in the cycle include all the 

 years of minimum sun-spots since 1810, and form 

 the minimum group of rainfall: 



TABLE I. 



Eleven Years' Cycle of Sun-Spots and Rainfall at Madras. 



1 Namelv, 1876,- 1865, 1854, 

 a " * 1866,1855,1844, 



3 " 1867,1856,1845, 



4 " 1868, 1857. 1S46, 



5 " 1869, 1858, 1847, 



6 " 1870, 1859, IMS 



7 " 1871, 1860, 1S49, 



8 " 1872,1861,1850, 



9 " 1873, 1862, 1851, 

 " 1874,1868,1852, 

 > '• 1875,1864,1858, 



2 " 1S76, 18G5, 1854, 



1S43, 1832, 1821, [1810. sun-spots only]. 

 1833, 1822, [1811, sun-spots onlv"|. 

 1884, 1828. [1812, sun-spots only]. 

 1885, 1S24. 1813. 

 1636, 1825, 1814. 

 I-: 1 ,?. 1826.1815. 



1838. 1827. 1816. 



1839. 1828. 1817. 



1840. 1829. 1818. 



1841. 1830. 1819. 

 1842,1831, 1820. 



1843, 1832, 1S21, [1810, sun-spots only]. 



The cyclic coincidence may be tested in an- 

 other way. If there is a true coincidence it should 

 disclose a well-marked minimum group at the ex- 

 tremities of the cycle (in the eleventh, first, and 



second years), and a well-marked maximum group 

 in the middle of the cycle (the fifth and following 

 years). The years on both sides of the central maxi- 

 mum group should yield intermediate results, and 



