IN writing upon. At subjeet extensive and impottset in its nature, so neatly interesting to every dosem Motion of melt, and] opoa which nothing satisfactory has hitherto beett offered to the woi'ld, the Author is sensible that he has engaged himself in an arduous undertaking, At a perieci when a libemlity of seetiw meat predominates; when men, emerging from ohm eagerly relinquish the errors and prejudices of their ancestors, something on the present. Subject seemed absolutely necessary to give still greater some sistency' to the teesofiiogs and speculations of met-em lciné.