372 Revieiiis, and Notices respecting New Books. 



mum, as to be almost, if not entirely, useless: indeed we apprehend 

 that the six-feet circles at the Royal Observatory are too large ; and 

 are firmly persuaded that two five-feet circles, with an increased 

 power of the telescope and of the microscopes, would give more 

 unvarying results than the larger instruments now used at Green- 

 wich. 



The work before us possesses additional interest, and derives ad- 

 ditional value from the well-earned tribute of praise which it offers 

 to the first astronomical instrument-maker of the present or of any 

 former age. Mr. Trougliton stands quite unrivalled in the construc- 

 tion of original astronomical instruments ; and from his peculiar ta- 

 lent they have acquired a degree of perfection that, with the present 

 means and materials of construction,will probably never be surpassed. 

 Indeed it is not easy to conceive that greater precision can ever be 

 attained in dividing the limb of a large circle, than is insured by the 

 application of the method of optical division which has been described 

 by the inventor in the Philosophical Transactions, and by our author 

 in Rees's Cyclopaedia. There are many other excellent artists in Lon- 

 don, particularly T.Jones of Charing-Cross, who was a pupil of the 

 celebrated Ramsden, and Simms, who is now Mr. Troughton's part- 

 ner ; and we feel confident that these will not think it any dispa- 

 ragement to themselves, when we assert that Troughton does, and 

 we believe always will, hold that rank among the makers of astro- 

 nomical instruments that Sir Isaac Newton does among philoso- 

 phers. To Mr. Troughton it must be peculiarly gratifying to find 

 the second volume of this work dedicated to him, in which he 

 makes so conspicuous a figure ; and in which is found a history 

 of several of his works, the existence of which perhaps might not 

 otherwise have been known, except at the different observatories 

 in which they are deposited. To Troughton this distinction was 

 justly due ; and we cannot forbear admiring our author's good taste 

 in paying him this tribute of respect. To several other eminent 

 artists in this department he has done full justice; and they also must 

 feel much gratification from the circumstance of having the results 

 of their ingenuity so ably and minutely described, by a person so 

 well capable of appreciating their merits, and of bestowing that 

 praise upon them which they have justly deserved. 



A work of this kind has long been a desideratum with persons 

 desiring to perfect themselves in the jyractice of astronomy. For 

 when we look at the iew works which are extant on the subject, 

 particularly in our own language, we really find nothing at all that 

 is adapted to the present improved state of astronomical science. 

 On this account the want has long been felt of some work, giving a 

 comprehensive detail of all the principal instruments in use, and 

 also of the precautions necessary to be adopted ; in order that such 

 instruments may be rendered as effective as possible. This is the 

 more requisite in the present state of the science, when errors, 

 which would have formerly passed without detection, or if detect- 

 ed, would have been considered insignificant, are now of so much 

 importance as to vitiate every result into which they are admitted. 



