Mechanical Philosophy. 71 



by our illustrious countryman. Dr. David Rit- 

 TENHOusE, and modestly called by him an Orrery, 

 after the production of Graham, is by far the most 

 curious and valuable, whether we consider its 

 beautiful and ingenious structure, or the extent and 

 accuracy with which it displays the celestial phe- 

 nomena/ 



Among the instruments for making astronomical 

 observations, invented during the last century, 

 there is none more important than the celebrated 

 Quadrant, invented by Mr. Godfrey, of Phila- 

 delphia, though afterv/ards claimed as a production 

 of Mr. Hadley, whose name it still bears. The 

 inestimable value of this instrument, for various 

 purposes, and especially for the direction of the 

 manner, is well known. Since the original plan 

 of constructing it was announced, improvements 

 ot much value have been suggested by the Rev. 

 Dr. EwiNG,^ Provost of the University of Pennsyl- 

 vania, by Professor Patterson,'^ of the same in- 

 stiUition, and by Mr. Magellan, of London. 

 We may next mention the Astronomical or Equa- 

 torial Sector, an instrument of great utility, in- 

 vented by the ingenious Mr. Graham, before 

 mentioned; the Transit and Equal Alt itmle Instru- 

 ment, first made for Le Monnier, the French as- 

 tronomer, by Mr. Sisson, of London; and the 

 Grand Astronomical Circle, by Borda and others, 

 the most complete and comprehensive instrument 

 in use among astronomers, being in fact a kind 

 of portable observatory, and probably carrying the 



/For a further account of this celebrated Orrery, see the Transacthns of 

 the American Philosophical Society, vol. i. Those who wish to see a brief and 

 comprehensive view of the genius, character and works of Dr. Ritten- 

 HousE, will find a good sketch of them in an Eulogium, pronounced ia 

 ftojiour ot his memory, before the American Philosophical Society, by Df, 



f Transactions of the American PhUosophical Society, voL k 

 ti UiJ. vol. IV, * 



