Farther than this, Smeaton's paper cannot be consider ed as describing an original method of graduation, the remainder being directed to the forming it into an engine, of which, in its proper place, we declined giving a descrip tion, and here it would be inapplicable. We may however observe, that Smeaton has improved upon Hindley in every patt, with his usual ingenuity and ability ; and pro vided the foundation were good, so would be the super structure. Smeaton was no advocate for large astrono mical instruments, and therefore would have an engine constructed of sufficient magnitude to graduate any that ought to be made.
Mr Smcaton's paper was not well received by the in strument makers ; but he predicted, that when half a cen tury had worn off the prejudice against it, the method would be adopted and improved to the advantage of astro nomy. But as Mr Troughton, in a paper to be noticed hereafter, ventures to make a quite contrary prediction concerning it, and gives his reasons for it, we decline en tering into the question.
Considering the celebrity of Mr Ramsdell, his long career and extensive practice in making instruments that requited the nicest graduation, we have in this depart ment of our article comparatively little to say of him. Ex cepting the descriptions of his engines, we believe he never wrote upon the subject ; nor has any one else, so far as we know, described how he proceeded. Troughton has indeed pointed out the manner in which he adjusted erroneous clots to their places ; a practice which it is said was sug gested to Ramsden by the adjustable waxed pieces of the Due de Chaulnes. A pupil of Ramsdell informs us, that in an early part of his practice he had used the scale of equal parts, agreeably to the manner of Bird, but that he soon abandoned it ; and that he had often varied his appa ratus and method. At what time the method of coaxing, as it is called, was first applied in the works of Ramsdell, is perhaps known to no one except Mr Berge : this artist, who at his death succeeded him, had long been his able and indefatigable assistant, and in the graduation of in struments had honoured the name of his employer, ny patient touches of unwearied art," That the coaxing could not have been in practice so early as the time when the dividing engine was made, may be inferred from the circumstance, that the descrip tion of the engine was given in upon oath, and nothing said about it.
For many years previous to the publication of the fol lowing method by Troughton, the art of graduation had been carried on in secrecy and silence ; every artist had, or pretended to have a method of his own, of which astro nomers could only judge, perhaps indeed the best way, by the comparative exactness of the work that came from their hands. Mr Troughton's paper was read to the Royal Society in February 1809, and appeared in the first part of the volume of the Phil. Trans. for that year.* It con tains not only an account of a method invented by himself, and which he had successfully practised for many years, but also remarks upon other methods, which had been, or were then in use. To abridge this work, after giving Birds's at length, is what we will not attempt ; for we think our readers may not be displeased to see Troughton's ideas upon the subject in general, expressed in his own way ; we therefore give the whole, notwithstanding a few repetitions, that will thus be introduced into our article.
" It would ill become me, in addressing myself to the members of this Society upon a subject which they are so well enabled to appreciate, to arrogate to myself more than may be assigned as my clue, for whatever of success may have been the result of my long continued endeavours, ex erted in prosecuting towards perfection the dividing of in struments immediately subservient to the purposes of astro nomy. A man very naturally will set a value upon a thing on which so much of his life has been expended ; and I shall readily, therefore, be pardoned for saying, that, con sidering some attainments which I have made on this sub ject as too valuable to be lost, and being encouraged, also, by the degree of attention which the Royal Society has ever paid to practical subjects, I feel myself ambitious of presenting them to the public through what 1 deem the most respectable channel in the world.
It was as early as the year 1775, being then apprentice to my brother, the late Mr John Troughton, that the art of dividing had become interesting to me ; the study of astro nomy was also new and fascinating ; and I then formed the resolution to aim at the nicer parts of my profession.