THE AMERICAN GLAZIER. 35 



new principle was necessary, by which the exact latitude in the path- 

 less ocean, ev^en amid the most agitating storms, might always be ascer- 

 tained. 



The invention of the instrument upon the optical principle of double 

 reflection, justly belongs to Godfrey, a native of Pennsylvania, and affords 

 a beautiful illustration of the faculty possessed by some individuals of 

 turning to profit the results of casual observation. Whilst, on a certain 

 occasion, he was replacing a pane of glass in a window opposite a pump, 

 a girl, after filling her pail, placed it on the side walk. Turning round, 

 Godfrey observed the rays of the sun reflected from the window into the 

 bucket of water, and a second time from the surface of the water to the 

 eye. His philosophic mind at once seized upon the incidental occur- 

 rence, and applied the principle to the construction of an instrument with 

 Avliich he could diaw the sun down to the horizon by means of a con- 

 trivance decidedly superior to any that had been known for the purpose 

 of ascertaining angular measurements. 



In addition to our own citizen, the merit of the invention has been 

 attributed to three individuals ; to Dr. Hooke, whose instrument admits 

 of only one reflection and therefore is not adapted to the object intended; 

 to Newton, whose description of it was communicated to the President 

 of the Royal Society, but by him was, for some reason, suppressed ; 

 and to Hadley, to whom the credit has been most generally ascribed. 



Abundant testimony, we think, can be furnished to establish the 

 claim of the American gazier to the honor ; and the most conclusive 

 is the letter addressed to Dr. Halley, President of the Royal Society, by 

 the celebrated James Logan, an individual not only prominent in the 

 early annals of this state, and at one time Secretary of the Common- 

 wealth, but also devoted to literature and the advancement of science. 

 In this letter, Mr. L. establishes the fact, that the Quadrant was not only 

 invented many years before the discovery of Newton's desciiption, but 

 was actually in use before the date of Hadley's claims. Godfrey first 

 constructed a model in wood and afterwards in brass. An experiment 

 of its adaptation to the purpose designed was made in 1730 during a voy- 

 age to the West Indies. In Jamaica it was exhibited to the Captain of 

 an English vessel, who took a description of it — some say the instru- 

 ment itself — and gave it to Hadley, a mathematical instrument maker in 

 London, who, after making some slight modifications in the construc- 

 tion, procured a patent for it. The statement of Dr. Franklin, one of 

 Godfrey's cotemporaries, may also be regarded as authoritative, in hi.s 

 diary we find the subjoined passage : "Among the first members of our 

 junto, was. Thomas Godfrey, a self-taught mathematician, great in hia 



