found in the pages of the Philosophical Magazine and Annals, and of 

 the Edinburgh Philosophical Journal. 



He was the first to make extensive use of the reflective goniometer 

 in determining the forms of the crystals of artificial salts. The An- 

 nals of Philosophy for 1823 contain the determination of the forms 

 of no less than fifty-five different laboratory crystals, a work of 

 much persevering labour. If only the chemical composition of these 

 salts had been accurately known in England at the time, their mea- 

 sures would have served as a basis whereon to found the theory of 

 Isomorphism. 



The treatise on Mineralogy in the Encyclopaedia Metropolitana 

 was the first systematic work on the subject with which the name of 

 Mr. Brooke is associated. This was originally intended to have 

 been a very complete treatise, but repeated editorial remonstrances 

 on account of want of space compelled our author to cut it down to 

 little more than a mere catalogue of minerals, with a few of their 

 more important chemical characters. The only complete treatise on 

 Mineralogy with which his name is connected is the recent re-edition 

 or rather reproduction of W. Phillips' s treatise, in conjunction with 

 Professor W. H. Miller, who took upon himself by far the greater 

 portion of the labour incidental to publication. 



It may be here remarked that Mr. Brooke entertained a strong 

 impression of the desirableness of rendering the study of crystal- 

 lography more attainable to many, whose minds are not so habituated 

 to the abstractions of analysis as to contemplate a plane merely as 

 the geometrical impersonation of ax-}- by + cz= : this object he pro- 

 posed to attain by means of a more direct reference of the existing 

 planes of crystals to simple geometrical, or primary, forms than the 

 last-mentioned treatise presents. 



Mr. Brooke's latest efforts were directed to the general relations 

 and geometrical similarity of all crystals belonging to the same sy- 

 stem. A paper on this subject, read before the Royal Society, which 

 was in the press at the time of his decease, contains a comparison of 

 the forms of all known minerals belonging to the Rhombohedral and 

 Pyramidal systems, and will probably be found to throw some new 

 light on the theory of Isomorphism. 



His unrivalled collection of minerals, comprising the choicest speci- 

 mens that he could, with ample opportunities, collect during half a 



