255 RADIUS' OF CURVATURE. 



H. 31. S. San Josef, in Torhay, \2th Dec. 1806^ 

 SIR, 

 and of the log. In obedience to your orders, we have been particular in 

 attending to the use of Mr. Edward Massey's Patent Log, 

 and from every opportunity that offered during our cruize 

 we are strictly of opinion, that it has the merit of accom- 

 plishing the end for which it is intended. , . 



On some trials made with it, and the common log, they 

 perfectly agreed, at other times they differed a little, but 

 last night bearingup forTorbay, with a run of eighty miles in 

 squally weather, there was a difference of nine miles : but 

 agreeably to our reckoning the patent log was perfectly cor- 

 rect; we therefore consider it an important improvement in 

 navigation, and the more so, as the instrument is simple 

 and easy to be generally understood. 



The chief things necessary to be observed are to secure 

 the tow-line as near the surface as possible, to prevent the 

 machine from quitting the Water in an agitated sea, and fast 

 sailing, and not to be less than sixty fathoms long in a first 

 rate, to prevent it from being affected by the eddy of the 

 ship's wake. 



^^Ve are, Sir, 



Your most obedient humble servants, 

 R. J. NEVE, Captain. 

 THOMAS MOORE, Master, 

 To sir Charles Cotton, hart., viccadmiral oj" the red, ^c. 



III. 



Observations on the Problem respediing the JRadius of Cur- 

 vature. In a Letter from W. Moore, Efq, 



To Mr. NICHOLSON. 

 SIR, 



A. F the following observations on the problem respecting 

 the radius of curvature, should be found to deserve a 

 place in your Philosophical Journal, the insertion of them 

 will greatly oblige, 



Sir, 



Vour most obedierit humble servant, 



W, MOORE, 



