1821 .] Machine for measuring a Ship's Way by the Log Line* 113 



driving rain with an east wind. In this case it ought to receive 

 much less, because the face of the cliff will receive all the raia 

 contained in the wind driven against it, and will drive upwards 

 the wind discharged of rain. If the wind drives up a slope, 

 instead of a perpendicular wall or cliff, the same thing will hap- 

 pen in a less degree ; and all irregularities of surface will more, 

 or less disturb the equaHty of distribution of rain ; and that in 

 different degrees under different directions of the wind. It is 

 also evident that as the rain driven away by the eddies must fall 

 somewhere, it will fall in increased quantities in irregular por- 

 tions elsewhere, and this will double the difference of indication 

 of guages at no great distance from each other. 



I am, Sir, your obedient servant, 



RiGHAKD Davenport. 



Article VIII. 



On the Machine for measuring a Ship's Way by the Log Line, 



(To the Editor of the Annals of Philosophy.) 

 ,^, MY DEAR SIR, 



The enclosed communication I received from a gentleman of 

 great respectability in Denmark. You will obhge me by insert- 

 ing it in the Annals of Philosophy. Very truly yours, 



G. FORCHHAMMER. 



Nothing is more probable than that two different persons may 

 have conceived similar ideas on any particular subject; and when 

 the inventions to which they give rise prove of essential utility, 

 it is but just that each should enjoy the honour that really is due 

 to him. 



It is stated in the Journal of Science and Arts, edited at the 

 Koyal Institution of Great Britain (vol. ii. p. 90), that Mr. New- 

 man has claimed to be the first inventor of a machine for measur- 

 ing a ship's way by the log hne. This is stated to vbe effected 

 by means of a sort of watch which is to serve on board of ships 

 in lieu of the usual sand glasses of one-quarter, one-half, or one 

 whole minute. 



Mr. Newman's description of his machine is as follows : 



" The quarter and half minute glasses in general used for 

 measuring a ship's way have always been found very irregular. 

 This irregularity arises from various causes, and particularly the 

 state of the atmosphere at different times, and in various lati- 

 tudes ; and even when they are new, it is scarcely possible to 

 find two that will run out in the same time. 



New Series, vol. i. h 



