Rain 



inches 



Rain inches 



1775 



5.5 24 



58-78 



1831 



—1776 



39-26 



50-25 



1832- 



1777 



62-07 



60-36 



1833 



1778 



59-30 



68-73 



1854 



+1779 



64-51 



85-50 



1835- 



1780 



64-20 



45-66 



1836 



1781 



59-90 



43-61 



1837- 



—1782 



41-07 



53-02 



1838 



1783 



52'22 



.... 



.... 



1784 



51-58 



.... 



.... 



-fl785 



69-75 



.... 



.... 



1839,] Rain and Drought of the last Eight Seaso?is in India. 315 

 Annual depth of rain at Calcutta in inches. 



It will be observed that the depths 

 are much less in the earlier period than 

 in the later. This is partly owing to 

 1836 ^he height °f the Gauge above the 

 ground in the former case, for which 

 allowance might be made, but this would 

 not be worth while, as there are other 

 sources of error which could not be cal- 

 culated. For the years 1784-85 we have another register published 

 in the Asiatic Researches, which gives the annual amount thus : — 



Year, 1784 1785. 



Inches, 81*0 77*5 



Let us now recapitulate the principal maxima and minima for 

 56 years. They are — 



Max. 1779. ..1786. ..1796. ..1806.. .1815. ..1822-23. ..1829.. .1835-36 

 Min. . . 1782-3. ..1792-3. ..1802. ..1811-12. ..1819-20.. .1826. ..1832 



The maxima for Bengal are generally earlier than the above. They 

 are, 1784-5 1794 1804 1813. 



On referring to the list we see that no minimum recurred at the end 

 of 56 years from 1782 viz. in 1838; but somewhat earlier, viz. in 

 1837. It was not, however, to be expected that the recurrences would 

 happen regularly in the same locality, and our lists are much too few to 

 enable us to estimate the average effect over the whole surface of the 

 country. The maxima above stated shew very nearly four equal in- 

 tervals of seven years each = 28 years ; one of ten years, and two of 

 nine years each = 28 years. 



Admitting the case to be as we have supposed, then we might 

 reasonably expect that similar phenomena would be observed in other 

 parts of the world, in particular, such lakes or large natural reservoirs 

 as the Caspian, and the North American lakes would indicate, by their 

 increase or diminution, the variations of the seasons over an extended 

 surface, better than any other artificial means that could be devised. 

 In Brewster's Edin. Journal of Science, vol. 7. 1827 (July to October), 

 we find a paper by Mr. De Witt Clinton, on the periodical rise and fall 

 of the North American lakes. Unfortunately no record has been kept 

 of the changes, but it is stated that there is a rise for three years, and a 

 corresponding declension — being altogether a period of six years. It is 

 added, that some extend the time of rise to five, and others to nineteen 



t t 



