PRELIMINARY REMARKS. 
7 
mittecl to it; as a body moving in great ocean rivers, as the 
Gulf stream, it also bears these materials forward to certain 
and well determined regions. It thus arranges and moulds the 
ocean’s bottom from the matter committed to it by the terres¬ 
trial rivers. By mechanical force the waves break down the 
strong rocky barriers of coasts, as well as those shores which 
are girded with sand. The ocean then is a moulder and dis¬ 
tributer of all the plastic matter committed to its bosom. In 
fine, moving water, under whatever name it has received, 
whether rivers, waves, tides, or ocean currents, is both destruct¬ 
ive and constructive, according to the conditions and circum¬ 
stances of the moving mass. 
The changes of temperature which a country undergoes, and 
the amount of rain which it receives, produce important changes 
in the physical condition of its surface. The observations 
which have been hitherto recorded are however too few to 
become the basis of important geological reasoning; yet they 
are sufficiently so to require some notice in this place. The 
following facts are recorded in the periodicals of the day, and 
are among the most important of this class: 
Mean Rain 
Latitude. Place. an. temp, in inches. 
Huntsville (9 years),... 51*13 
Natchez (8 years),... 64*76 
Columbia, S. C ,.. 56*8 49*90 
Washington, D. C. } . 56‘57 
39° 56' Philadelphia, . 53'42 
39° 06' Cincinnati, 510 ft. above tide water,... 53*78 
41° 14' Hudson, Ohio (3 years,) 9 A. M., .... 48*7 37*63 
(The amount of rain varies some nine or ten inches.) 
The average at 3 P. M., ........... 55*6 
Trenton, N. J.,... 48*22 
For six summer months,. 60’60 
Wintermonths,... 35*79 
Prevailing winds S. W. 
State of New York— 
40° 37' Flatbush, L. I.,. 51*25 
41° 30' Newburgh (17 years), . 48*96 35*54 
Albany, do ... 48*27 39*91 
