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Mr. Troughton on dividing Instruments, 
Ramsden’s well known method of dividing by the engine 
unites so much accuracy and facility, that a better can hardly 
be wished for ; and I may venture to say that it will never be 
superseded, in the division of instruments of moderate radii. 
It was well suited to the time in which it appeared ; a time 
when the improvements made in nautical astronomy, and the 
growing commerce of our country, called for a number of 
reflecting instruments, which never could have been supplied, 
had it been necessary to have divided them by hand ; how- 
ever, as it only applies to small instruments, it hardly comes 
within the subject of this paper. 
The method of Hindley, as described by Smeaton,* I will 
venture to predict will never be put in practice for dividing 
astronomical instruments, however applicable it might for- 
merly have been for obtaining numbers for cutting clock- 
work, for which purpose it was originally intended. It con- 
sists of a train of violent operations with blunt tools, any one 
of which is sufficient to stretch the materials beyond, or press 
them within their natural state of rest ; and, although the 
whole is done by contact, the nature of this contact is such as, 
I think, ought rather to have been contrasted with, than re- 
presented as being similar to, the nature of the contact used 
in Smeaton ’s Pyrometer, which latter is performed by the 
most delicate touch ; and is represented, I believe justly, to 
be sensible to the part of an inch. Smeaton has, how- 
ever, acquitted himself well, in describing and improving the 
method of his friend ; and the world is particularly obliged to 
him for the historical part of his paper, as it contains valuable 
information which perhaps no one else could have written. 
* Phil. Trans, for 1788. 
