410 Additional Notes. 



from thy great sagacity and industry, some advances towards 

 it, far exceeding all former attempts, from the motion of the 

 moon, to the ascertaining of which thy labours have so long 

 and happily been directed; the following notice, I hope, will 

 neither be thought unseasonable, nor prove unacceptable. 

 That the success of this method depends on finding the Moon'a 

 true place for one meridian by calculation, and for another by 

 observation, I think is generally allowed; the first of which 

 being depended on from thy great genius, what remains k 

 some certain method for observation, practicable on that un- 

 certain element, the sea. In order to this, thy predecessor at 

 Greenwich^ if I mistake not, for some years, published his 

 calculations for the moon's future appulse to the fixed stars, 

 which would save all observation, but that of- a glass; but 

 these not often happening, and the moon often having a con- 

 siderable parallax when they did, that project dropt. 



For finding her place by taking her greater distances from 

 stars, the fore-staff or cross-staff cannot be exact enough: 

 and Quadrants, Sextants, &;c. with two Telescopes, are im- 

 practicable at sea. 



Dr. Biester's late proposal for taking the difference of 

 rad. ascension between the moon and a star, if that should 

 prove practicable with sufficient exactness, would undoubtedly 

 answer the intention of all that is to be expected from the 

 moon, if lier place were taken on or near the meridian. But 

 to keep tlie arch of this instrument in the plane of the equa- 

 tor, and, at the same time, view two objects of unequal al- 

 titudes, and considerable distance from each other, by the 

 edges of two sights, with the necessary accuracy, will not, 

 perhaps, be so easy in praciice as he would have it believed. 



1 shall, therefore, here presume, from thy favour shown 

 me in England, in ni:J4, to communicate an invention that, 

 whether it answer the end or not, will be allowed, I believe, 

 to deserve thy regard. 1 have it thus; 



A young man, born in this country, Thomas Godfrey 

 by name, by trade a glazier, who had no other education 

 than to learn to read and write, with a little common arith- 

 metic, having, in his apprenticeship with a very poor man 

 of that trade, accidental! y met with a mathematical book, 

 took such a fancy to the study, that, by the natural strength 

 of his genius, without any instructor, he soon made himself 

 master of that, and of every other of the kind he could bor- 

 row or procure in Englisli ; and finding there was more 

 to be had in Latin books, under all imaginable discouiage- 



