PREFACE. vii 



references, when judiciously distributed and arranged, will serve, like the 

 index of a book, but much more effectually, to conduct the reader from one 

 subject to another : they will enable him to perceive their relation to eacli 

 other ; and they will direct him how to collect and combine the dispersed 

 parts of any science into one entire and regular system. Each article will 

 afford him, as it were, a distinct lecture ; and he may pursue the same 

 course of study by the means now suggested, or vary it as he thinks proper. 

 Upon the whole, the advantage of separate treatises under each head of 

 science, such as the limits of a dictionary will allow, seems to be more 

 imaginary than real ; more especially as the want of them may be supplied 

 in the manner that has been mentioned. 



In conformity to our proposed plan, it has been our endeavour to give, 

 under each distinct head of science, an historical account of its rise, pro- 

 gress, and present state, concisely and yet as comprehensively as our limits 

 and our sources of information would allow ; to refer to those articles in 

 which the discussion of them occurs, and to point out such publications as 

 afford further information. References of this kind are introduced under 

 each separate article, wherever they are thought to be necessary and useful ; 

 and thus the reader is able to form his judgment concerning the authorities 

 upon which the compilers of the several articles depend ; and if he shall 

 have opportunity or inclination, he may recur to them for himself. 



Whilst the Editor and his co-adjutors in this work have availed themselves 

 of the assistance which other similar dictionaries have afforded them, they 

 have not contented themselves with mere transcripts ; they have resorted as 

 much as possible to original writers, which they have been enabled to do by 

 the facility of their access to large libraries; and by the citations which 

 they subjoin to the several articles, the Public will judge of the extent of 

 their research, and of the industry and labour which they have bestowed 

 on this compilation. In their account of the arts and manufactures, they 

 have consulted the artisans and manufacturers themselves, and derived from 

 them every kind of information that was likely to conduce to the credit and 

 utility of the work : and this they have not been able to do without incur- 

 ring a very considerable expence. 



Some apology may, perhaps, be thought necessary for the extension of 

 this work beyond the limits first proposed. Wlien it was determined to 



