222 Parallel of Rome de V Isle's and 



the same time, " it will cost me 2l. Os. 6d. to hew this 

 timber and carry it to London, where it will only fetch 

 7l. 2s. 6d. per load," he would instantly conclude what he 

 would think a good bargain; not suspecting that the diffe- 

 rence of measure (if hewn, as in the last example,) could 

 put nearly 1 1. 12 s. per load, or 31 per cent, into the pocket 

 of the dealer. . 



It may be proper to add, that the way to examine any 

 lot of hewn timber, with the view of determining to which 

 line of the above table it should be referred, is to take the 

 calliper in inches of several of the trees indiscriminately 

 chosen in the middle or girting place, first on each of their 

 sides, or in the directions A a and A a, and place the results 

 under each other in a column, and next callipering them in 

 the same place but at the corners or in the directions Bb 

 and Bb, placing these likewise in a column; then dividing 

 the sum of the first column by the sum of the second co- 

 lumn, and carrying the division to three or four places of 

 decimals, the quotient or result is to be sought for in the 

 first column of the table. 



Hoping that I have made the above intelligible, and that 

 the table will not be unacceptable to the growers of timber, 

 their agents, and others. 



I remain, my lord, your lordship's 



most obedient and humble servant, 

 Grown-strcfit, Wesminster, JOHN FAREY. 



May 30, 1803. 



XXXJX. Parallel of Rome de LTsle's and the Able 

 IIauy's Theories of Crystallography* 



[Continued from p. 172.] 



Synthesis is grounded, as I mentioned, on the fact, that 

 all well formed crystals are terminated by plane surfaces. 



Since there exist primitive forms, there must also be se- 

 condary forms, for the one supposes the existence of the 

 other. The secondary forms are such, that sections can be 

 made only parallel to the sides of the primitive ; and when 

 th^ primitive has been produced by these sections, the di- 

 vision being continued the integrant particles are. obtained. 



The mineralogical analysis descends from the secondary 

 to the primitive form, and from the latter to the integrant 

 particle; just so the mineralogical synthesis ascends from 

 the integrant particle to the primitive, and from thence to 



' the 



