V1U PREFACE. 



work, it would be presumptuous for us to hope that we have been 

 entirely successful in our earnest endeavors to render the Annual 

 perfectly accurate, and we must plead, in excuse for any errors which 

 may be detected, the peculiar difficulties necessarily attending the 

 preparation of the first volume of a work of this nature. 



We must not neglect this opportunity of acknowledging the aid 

 we have received from many distinguished gentlemen, but especially 

 from Professors Agassiz, Horsford, and "Wyman, and Dr. A. A. 

 Gould, whose counsel and assistance have greatly aided us in our 

 labors. To Messrs. Folsom and Fairbanks, of the Boston Athe- 

 naeum, and Messrs. Harris and Abbott, of the library of Harvard 

 College, we are indebted for many facilities. 



Should this our first volume receive the approbation of the public 

 the work will be continued annually ; and while we hope hereafter 

 to be free from some embarrassments which have prevented us from 

 making it as complete as we could desire, the experience already 

 gained and the aid promised for the future will, we believe, enable 

 us to render the succeeding volumes more satisfactory both to the 

 public and ourselves. 



"VVe shall be happy to receive original communications relating to 

 new inventions or discoveries, for insertion in the next volume. 



CAMBRIDGE, March 1, 1850. 



NOTE TO THE SECOND EDITION. 



THE Editors have improved the opportunity afforded by the rapid 

 sale of the first edition and the consequent demand for the new one, 

 by correcting a few errors, which had previously escaped notice. 

 The list of scientific publications and the index to articles in scientific 

 journals have been considerably enlarged. "We hope, hereafter, to 

 render this important feature of the work still more valuable. 



APRIL 10, 1850. 



