338 Review of Alhn^s Mechanics. 



higher than the surface of the ground in an extensive surroundmg 

 country. Hence by sinking a shaft that may penetrate this stratum, 

 a flow of water would be obtained at the surface of the ground. 



Another observation may be made with regard to the vapor exha- 

 lations from the earth. In the winter,* the earth receives no water 

 by rains, yet the surface of the ground, in cold latitudes, obtains 

 moisture sufficient to be frozen into a solid crust ; and all springs and 

 wells give a full discharge of water. Rivers that are supplied by 

 springs, are also found to contain more water in winter than summer, 

 although nothing is received from the surface of the ground. 



Art. X. — The science of Mechanics as applied to the present im- 

 provements in the useful arts in Europe, and in the United States : 

 adapted as a Manual for Mechanics and Manufacturers ; by 

 Zachariah Allen. Providence, R. I. 1829. 



(Communicated.) 



This is the first work of tlie kind, of domestic origin, thai has been 

 put into the hands of our practical mechanics and manufacturers. 

 Some of the subjects contained in it, have appeared in separate trea- 

 tises and in periodical journals, but no American book has hitherto 

 been published, calculated to afford instruction in so many depart- 

 ments of a manufactory and workshop, as the one before us. Rob- 

 inson's Mechanical Philosophy, and Brewster's edition of Ferguson's 

 Mechanics, pubhshed in England, can seldom be procured in this 

 country. Nicholson's Operative Mechanic, and Gregory's Mechanics, 

 republished in Philadelphia, have served as books of reference to our 

 millwrights and machinists, and in connexion widi the Encyclopffi- 

 pia, have been their principal sources of information. These works, 

 however, contain a great amount of matter totally irrelevant to the 



* The writer doubtless intends the winter of polar regions, as in the winters of tlic 

 temperate latitudes, rain is not an uncommon occurrence. A question will of course 

 arise as to the origin of the subterranean water, which affbid.s tlie exba^aiions; and 

 the writer intimates no opinion, whether it is ultimately derived from percolation, 

 from rains and waters upon the surface, which are thus ultimately, although, itriiay 

 be, variously and unequally distributed through the interior of the earth, or whethei-, 

 as some geologists suppose, there may be great subterranean reservoirs of water. 

 This, however, will not militate against the author's hypothesis, for from whatever 

 sources the water may he derived, it i: fair to reason upon the formation and condeu- 

 satiou of its vapor. — Ed. 



