XVI PREFACE. 



edges of the prism; such however, that any three plates at 

 angles of 120 have an equal acoustical elasticity. He 

 found also that by the acoustical properties he could deter- 

 mine the cleavage planes of Quartz, and in general whether 

 a given portion of a mineral belongs to a simple crystal, or 

 to a mass of compound individuals, as the vibration in the 

 different cases gives corresponding differences of note, 

 amounting to a full tone. 



Besides its own peculiar attractions, and the recommen- 

 dations it possesses from its affiliation with many branches 

 of general Physics, there is necessarily superadcied to min- 

 eralogy in this country a strong interest arising out of the 

 unexplored state of its mineral riches. By far the largest 

 part of our territory still waits for the first labors of the Min- 

 eralogist ; and as proof that the full harvest of discovery has 

 not yet been gathered in even in the New England states, 

 New York, New Jersey and Pennsylvania, in which mine- 

 ralogical inquiries commenced, and where they have been 

 followed up with the greatest activity, it needs only to be 

 mentioned that these stales still continue to develope with 

 each passing year, discoveries of increasing interest. Should 

 the present work contribute to promote investigations so in- 

 viting in themselves, and so important to mankind, whereby 

 the science may reap fresh acquisitions, and the country 

 increased resources, I shall experience a reward greatly be- 

 yond the merits of such imperfect labors. 



CHARLES U. SHEPARD. 

 New Haven, May, 1835. 



