42 



was knocked down by a horse suddenly turning the corner of a road 

 near his residence at Stockwell, and the fall produced a slight con- 

 cussion of the brain ; after which, for a considerable period, his 

 accustomed mental efforts were followed by sleeplessness and other 

 symptoms of undue cerebral excitement. During this period, finding 

 absolute inaction extremely irksome, he sought pursuits which would 

 occupy his hands, with less demand on the brain than those to which 

 he had been devoted. He formed a large collection of shells, but 

 feeling the pursuit to be objectless, if irrespective of the structure 

 and functions of their living tenants, he abandoned it, and presented 

 the collection to the University of Cambridge. Mr. Brooke then 

 became a collector of engravings, having in early life imbibed a 

 taste for art, and exercised that of water-colour drawing. These he 

 was so successful in cleaning and restoring, that when, having so far 

 recovered as to resume his original pursuits, he disposed of his collec- 

 tion, the aggregate value was greatly augmented, notwithstanding the 

 presentation of some specimens of rare excellence to the national 

 collection in the British Museum. 



Having been blessed to the last with an unusually perfect enjoy- 

 ment of his faculties, his favourite studies were actively pursued until 

 a very short period before his decease, which occurred from natural 

 decay, accelerated by the depression of the system produced by a 

 severe cold, on. the 26th of June, 1857. 



The ' Familiar Introduction to Crystallography,' the first system- 

 atic treatise on this branch of science, was published in 1823. In 

 this, following the steps of Haiiy, he referred the existing forms of 

 crystals to an unnecessarily large number of primary forms ; but the 

 trigonometrical relations of the various existing plane surfaces of 

 crystals were then first clearly traced out. 



In the subsequent treatise on Crystallography published in the 

 Encyclopaedia Metropolitana, the former system was much simpli- 

 fied and the number of primary forms reduced to six, which, differing 

 essentially from each other, correspond with the six systems generally 

 adopted by continental crystallographers. 



The discovery and description of thirteen new mineral species are 

 due to Mr. Brooke's researches : to these may be added two others, 

 the published descriptions of which were just anticipated, in point of 

 time, by those of continental mineralogists. These notices will be 



