310 Transactions of the American Institute. 



the law of gravitation, extended to the planets, revealed a more 

 exact system of longitudes, thus giving increased security to com- 

 merce. 



Was it then surprising that this law should obtain in the domes- 

 tic history of families? In the fluctuations of colleges, congi-ega- 

 tions and political parties? In the circulation of periodicals, in 

 epidemics, and in vast conflagrations? In the transmission of letters 

 and telegrams? The number of passengers, and freightage? In 

 the accidents of travel, marine losses, fisheries, and in the annual 

 yield of fruits and harvests? 



I had previously learned, from the writings of M. Quetelet, that 

 choice itself was no antagonist of this law, as applied to mental 

 and moral contagions, and the designed destruction of persons and 

 property. 



But that which fixed my attention particularly was your published 

 list of the famines and periods of scarcity in France during the last 

 three centuries, whence" you deduce a septennial failure, adding 

 that this law is applicable to other countries, and concluding that 

 this is " plainly owing to some law of nature, yet undiscovered, that 

 these unfruitful seasons recur at comparatively regular periods." 



This "undiscovered law" was the very one which engaged my 

 investigations, and I soon found similar facts, viz: "Four drouths 

 in Montgomery county, Md., at intervals of sixteen years; in parts 

 of Illinois, a similar recurrence in seven years; a change in the 

 Delaware peach hai-vest in twenty years; and in Texas, a general 

 expectation among the old settlers, of abundance every twenty 

 years." 



Closely connected with this periodic agricultural law was a field 

 where chance hitherto held sway, viz: meteorology and fluviology; 

 for, if by certain, though partially discovered law, we may predict 

 the coming stomi, we may with equal facility anticipate the river 

 flood — a cycle of modified vapor — "the waters above the waters." 

 It is remarkable that while much attention has been given to meteo- 

 lology, this river law and the agricultural cycles, have been over- 

 looked; and yet the connection between the two is so indissoluble 

 that any fact discovered in the one must elucidate the other. I 

 might further suggest that the septennial fallow of the Jewish law, 

 may have been this veiy undeveloped periodicity, written ages 

 previously, on the ground itself. 



In the report for 1865, page 572, the Agricultural Department 

 at Washington published the above facts, calling the attention of 



