[ 3^0 ] . 



hammer, of about 1 2lb. were laid on in order to 

 dole them to the fides of the (haft; which being an 

 octagon, and not a cylinder, could not be effected 

 by any other means. 



- This was the method practifed in (lengthening 

 thofe (hafts already in gearing; but if it (hould be 

 thought expedient to ufe them in conftruction, they 

 may be applied to more advantage ; for inftead of 

 one revolution of the fpiral, it may have two; in 

 which cafe the advantage will be double : add, that 

 in both cafes there may be as many fpirals as there 

 are arms in the wheel. 



I am, Sir, your obedient fervant, 



J. C. HORNBLOWER. 



N. B. It has not been thought advifeable to attempt any 

 representation on a plate, of the model accompanying this 

 letter; but our mechanical readers, who have any curio- 

 fity to fee it, may be gratified, by applying at the Rooms of 

 the Society. 



Article XXXIX. 

 Sir, Wejl-Moncktoti) March 6, 1788. 



BEING (truck very forcibly with the importance 

 of the fubjecl:, I fometime ago committed the 

 inclofed thoughts to writing, not at that time with 



any 



