177^. ROUND THE WORLD. 59 



Which is nearly the same difference as the day 

 before. But Mr. Wales and I took each of us six 

 distances of the sun and moon, with the telescopes 

 fixed to our sextants, which brought out the longi- 

 tude nearly the same as the watch. The results 

 were as follows : By Mr. Wales 38 35' 30", and 

 by me 38 3& 4*5". 



It is impossible for me to say whether these or the 

 former are the nearest the truth, nor can I assign 

 any probable reason for so great a disagreement. 

 We certainly can observe with greater accuracy 

 through the telescope, than with the common sight, 

 when the ship is sufficiently steady. The use of 

 the telescope is found difficult at first, but a little 

 practice will make it familiar. By the assistance of 

 the watch, we shall be able to discover the greatest 

 error this method of observing the longitude at sea is 

 liable to ; which, at the greatest, does not exceed a 

 degree and a half, and in general will be found to 

 be much less. Such is the improvement navigation 

 has received by the astronomers and mathematical 

 instrument-makers of this age ; by the former from 

 the valuable tables they have communicated to the 

 public, under the direction of the Board of Longitude, 

 and contained in the astronomical ephemeris ; and by 

 the latter, from the great accuracy they observe in 

 making instruments, without which the tables would, 

 in a great measure, lose their effect. The preceding 

 observations were made by four different sextants, of 

 different workmen ; mine was made by Mr. Bird ; one 

 of Mr. Wales's by Mr. Dollond ; the other, and Mr. 

 Clerke's, by Mr. Ramsden ; as also Mr. Gilbert's 

 and Smith's, who observed with the same instrument. 



Five tolerable fine days had now succeeded one 

 another. This, besides giving us an opportunity to 

 make the preceding observations, was very service- 

 able to us on many other accounts, and came at a 

 very seasonable time. For having on board a good 

 quantity of fresh water or ice, which was the same 



