MXS. SOMERVILLE. 5 



was originally intended to form one of the works 

 published by the Society for the Diffusion of Useful 

 Knowledge, though it soon outgrew the dimensions 

 suited for such a purpose. Indeed, it is remarkable 

 that either Mrs. Somerville herself or Lord Brougham, 

 at whose suggestion the work was undertaken, should 

 suppose it possible to epitomise Laplace's magnum 

 opus, or so to popularise ft as to bring it within the 

 scope of the Society's publications. 



It will be well, in weighing the value of the book, 

 to consider it first with reference to the purpose of its 

 author, though a judgment based on that consideration 

 alone would not be a fair one. These, then, are the 

 words in which Mrs. Somerville presents the scope and 

 purpose of her work : 



' A complete acquaintance with physical astronomy 

 can only be attained by those who are well versed in 

 the highest branches of mathematical and mechanical 

 science : such alone can appreciate the extreme beauty 

 of the results, and the means by which these results 

 are obtained. Nevertheless, a sufficient skill in ana- 

 lysis to follow the general outline, to see the mutual 

 dependence of the several parts of the system, and to 

 comprehend by what means some of the most extraor- 

 dinary conclusions have been arrived at, is within the 

 reach of many who shrink from the task, appalled by 

 difficulties which perhaps are not more formidable than 

 those incident to the study of the elements of every 

 "branch of knowledge, and possibly overrating them by 

 not making a sufficient distinction between the degree 



