370 On the Improved Dhnding Engine. 



also, that it was a method that would he attended with con- 

 siderable expense, and which I could bi;t ill afford at the 

 time, haviiiir spent so much of my time and earnings in 

 gaining experience by making the former engine. The next 

 idea was the ring; which 1 saw would be attended with 

 considerably less'expense, and would answer the same pur- 

 pose if well executed : for here only one particular point 

 required to be carefully attended to, viz. to make the rabbet 

 true which was to receive the ring ; for it was evident, that 

 if that were turned sufficiently true, the ring would be sure 

 to shift correctly. 



1 was so well aware of the necessity of strictly attending 

 to this point, that I did not content myself with having the 

 rabbet turned on its own axis in the lathe ; but after I had 

 if fitted on its own stand, where it now acts, \ fixed a tool 

 with an adjustment to touch the rabbet where the ring is 

 fitted on ; and by moving the wheel horizontally round to 

 the said tool, 1 found tliat 1 got it extremely true. This 

 being done, I fitted on the ring, and then found that it would 

 move very correctly lo opposite lines or divisions. Which 

 circumstance gave me tull confidence that I had obtained 

 my object. 



In the description which I gave to the Society of Arts, 

 I made mention of steady pins, which I find does not please 

 some of the critics. I understand that they imagine that the 

 steady pins are made fast in the rings, but which is not the 

 case. The holes that I broached with the stop- broach were 

 through both substances, and which I got true by shifting 

 the ring to halves and quarters as I broached. I then fitted 

 in steel pins, which would push out and in every time that 

 I shifted li>e ring. I, however, placed more dependence on 

 the opposite lines than on the steady pins; but tht-se were 

 useful in assisting me to shift the ring correctly to the op- 

 posite lines or divisinns. 



That the anonymous author above alluded to does not 

 understand the subject that he writes on, is evident frotTi 

 one circumstance, namelv, his comparing my improvement 

 on the dividmg engine of Rani^cltn with Mr. Troughton's 

 method of dividing huge circles by hand; — two things which 

 are as diifcrent from each other as light is from darkness. 

 ll-e makes his conclusion (alter finding all the faults with 

 iny method that he can) by saying, that under all ihe cir- 

 cumstances of the-case, we must give the preference to Mr. 

 'I'rougiiton's method of dividing ; although Mr. Troughton 

 himself, in his description, says that ii has nothing to do 

 with Mr, Hamsdca's engine. V>y hazarding such remarks 



the 



