a7td the actual Forms of Inorganic Bodies. 145 



are affected, such a mode of conceiving of these phenomena may 

 form a very legitimate resting place for the mind. 



In conformity with this method, then, adopted in other 

 branches of science, I have, in the preceding pages, endeavoured: 

 to shew that the form of every inorganic lx)dy, possessing indi- 

 vidualitv, may be regarded as the result of antagonist forces: 

 One, which may be compared to a central force, ever tending 

 to group the aggregating particles in the most symmetrical man- 

 ner possible, and possessing therefore a uniform definite agency, 

 and entitled as much as any other phenomenon to the name of 

 a law of nature ; the others, of specific characters having their 

 origins in the particular forms of the particles aggregating ; or, 

 in other circumstances, of unknown nature. 



Auffwt 14. 1832. 



A few Remarks on the Relation zvhich subsists between a Ma- 

 chine and its Model, By Edwakd Sang, Teacher of Ma- 

 thematics, Edinburgh. Communicated by the Author. 



At first si^ht, a well constructed model presents a perfect re- 

 presentation of the disposition and proportion of the parts of a 

 machine, and of their mode of action. 



Misled by the alluring appearance, one is apt, without enter- 

 ing minutely into the inquiry, also to suppose that the perform- 

 ance of a model is, in all cases, commensurate with that of the 

 machine which it is formed to represent. Ignorant of the inac- 

 curacy of such an idea, too many of our ablest mechanicians and 

 best workmen waste their time and their abilities on contrivances 

 which, though they perform well on the small scale, must, from 

 their very nature, fail when enlarged. Were such people ac- 

 quainted with the mode of computing the effects, or had they a 

 knowledge of natural philosophy, sufficient to enable them to 

 understand the basis on which such calculations are founded, 

 we would see fewer crude and impracticable schemes premature^ 

 ly thrust upon the attention of the public. This knowledge, 

 however, they are too apt to regard as unimportant, or as diffi- 



• Read before the Society of Arts for Scotland, 28th November 1832. 

 VOL. XIV. NO. XXVIT. .JANUARY 1838. K 



