PREFACE. 



THE idea of preparing the present work was first suggested by 

 the examination of similar works, which have been published in 

 Europe for several years past. We believed that such a work could 

 not fail to be useful to many persons, by enabling them to see at a 

 glance what has been accomplished during the past year, and thus 

 showing them in what direction they can most profitably apply their 

 labors. The language of Bacon concerning one branch of science 

 applies with equal force to all its branches : " Nothing is of greater 

 efficacy in procuring a stock of new and useful inventions, than to 

 have the experiments of numerous mechanic arts known to a single 

 person or to a few, who might mutually improve each other by con- 

 versation; so that by this translation of experiments, arts might 

 mutually warm and light up each other, as it were, by an inter- 

 mingling of rays." 



In the preparation of the Annual, nothing has been inserted ex- 

 cept upon good authority. While many of the articles have not 

 been previously in print, many others have been furnished directly 

 to us by their authors, but have also been published elsewhere. In 

 the exercise of a proper discretion, we have rejected some articles 

 which it would perhaps have been well to retain ; but the limits 

 assigned to the work compelled us to omit much that we at first 

 intended to include. We have, however, inserted nearly all that is 

 at once new and important which is to be found in the standard sci- 

 entific publications of America, Great Britain, France, and Germany. 



Although great care has been bestowed upon every portion of the 



