208 Machine to measure a S/iip^s Way bi/ the Log Line, [March^ 



hole to have been made in the centre of the wire gauze, and 

 sometimes the parallel wires were forced wider. This was very 

 often the case when apiece of wire gauze was put at all the join- 

 ings, fl, b, and r, and then it was the gauze at a which was torn 

 or otherwise injured. 



Experiment 17. — In order to ascertain if the flame still remained 

 unaltered, notwithstanding its having passed through the finest 

 wire gauze, a quantity bf gunpowder in flannel was aflixed to the 

 bottom of the apparatus ; and it was inflamed through one, two, 

 and even three pieces of the gauze. Here the same occasional 

 appearance, noticed in the last experiment, occurred with regard 

 to the upper piece of wire gauze. 



I am, yours respectfully, 



John Deuchar. 



Article X. 



On a Machine to measure a Ship's Way hy the Log Line. 

 By Mr. J. Newman 



(To the Editor of the Annals of Philosophy.) 



DEAR SIR, 



I OBSERVE in the last number of the Annals of Philosophy a 

 paper referring to the account I have given of a machine to 

 measure a ship's way by the log Une, in which a prior claim to 

 mine is set up for the invention. This I conclude to arise from 

 the circumstance of my not having mentioned the date of the 

 instruments I made ; and from it yoiir correspondent supposes 

 that the date of the publication of the paper is that of the 

 invention. 



It is now at least 40 years ago since I invented and made the 

 first instrument in question. Capt. Hubbard, then of the East 

 India service, had the first of them, and between the years 1785 

 and 1798 they were publicly sold by Messrs. P. and J. Dollond, 

 and Mr. George Adams, with their names on them ; but my 

 account book of that time is destroyed. My present account 

 book begins in 1794, and I find that Messrs. DoUonds had one 

 of the instruments on Sept. 4, 1797 ; and another on the 27th of 

 the same month. These dates can no doubt be easily verified 

 by reference to their books. I made several, perhaps 16 or 18, 

 between the dates I have mentioned, but my attention being 

 called to other things, I did not pursue the subject with any 

 degree of earnestness. I remember that Capt. Clayton had one 

 of the first that I made in the year 1785, and he recommended 

 me to take it to Sir Charles Middleton, at the Navy Office, 



