IV PREFACE. 



spared to improve it in every particular. Among these addi- 

 tions are the Meteorological Tables, prepared expressly for us, 

 the tables of Weights and Measures, and the Review of the 

 Year, into which, while glancing at the progress made in the 

 world of science, we have introduced much interesting infor- 

 mation. 



In regard to the Index to Articles in Scientific Journals, we 

 would say, that it is not intended to be a complete index to such 

 journals, but simply to embrace references to such articles as 

 contain important or interesting information, and are not no- 

 ticed in the body of the work. Great irregularity has been 

 experienced in the reception of our foreign journals, which fact 

 will account for some apparent omissions on our part. Want 

 of room has compelled us in general to omit extracts from new 

 books sent us, but we shall endeavour to supply the defect here- 

 after. 



The favorable reception which the Annual has received in- 

 sures its continued publication, but it is highly probable that 

 hereafter some important changes will be made in it, by which 

 its value will be further increased. We should be happy to re- 

 ceive original communications, provided they are in our hands 

 as soon as the first of December. 



CAMBRIDGE, February 1, 1851 



