170 GEOLOGICAL SURVEY OF NEW JERSEY. 



maximum from 1850 to 1860, and while the rain-fall at Newark 

 and New Brunswick may have been somewhat below the aver-, 

 age during those years, it certainly was not less in either the 

 New York, Philadelphia or Morrisville records than it was 

 earlier, and it was more in the Philadelphia record than it was 

 from 1825 to J 835. On the other hand the period of droughts 

 extending from 1869 to 1883 at New York and Newark, 

 and from 1874 to 1885 at New Brunswick, Trenton and Phila- 

 delphia, occurred after the forests had begun to grow again, and 

 had improved materially in the northern part of the State. But 

 taking a rather wide radius around Philadelphia there has been, 

 on the whole, progressive deforestation at a slow rate up to the 

 present time ; that is, the forest area has decreased. The Phila- 

 delphia record for the entire period of seventy-five years shows 

 no corresponding diminution in the amount of rain-fall. 



Indeed, it has been pointed out in Bulletin D, of the U. S. 

 Weather Bureau, that there has been a general tendency to in- 

 creased rain-fall in New England from 1834 up to the present time. 

 We have examined the long record at Troy, New York, and 

 this shows the same characteristics that we have pointed out in 

 the diagrams of New York and Philadelphia rain-fall, namely, 

 a progressive increase of rain-fall from about 1839 to about 1870, 

 with wide fluctuations since the latter date. 



The following table shows the result of grouping and aver- 

 aging the rain-fall of New York, Newark, New Brunswick, 

 Trenton-Morrisville and Philadelphia, by five-year periods : 



Average Annual 

 Yeats. Rain-fall. 



1825-1829 37.52 



1830-1834, 4T-3 2 



i835- I 839> 42.50 



1840-1844, ... 44 33 



1845-1849 ^ 42.78 



1850-1854, 46.00 



1855-1859, 44-53 



1860-1864, .... 45.81 



1865-1869 . . 49.16 



1870-1874 48 05 



1875-1879 43. 6 3 



1880-1884 42 04 



1885-1889 . 49.50 



1890-1894 . 45-75 



1895-1899 46.16 



