350 



ISlr. J. R. Napier on Velocity of Ships. 



Should we take the silver coining in the same way, it seems vastly 

 superior as a commercial speculation, — 1 lb. of the tin aUoy will not cost 

 more than Is. 6d., and will produce about 96s. These, however, are 

 often disposed of to venders at three and four for Is., thus reducing the 

 profits — this, along with the risks of detection, imprisonment, &c., 

 necessitates the silver coiner to belong to the lowest class of society ; but 

 both the copper coin and coiners of them maintain their position in 

 society, it only requh'ing that he keep his trade secret, the name coiner 

 not being legal as a private manufacture. 



The following is the standard weight of each coin when new : — 



Description of an Instrument for Measuring the Velocity of Ships, 

 Currents, tfc. By Mr. James E. Na:piek. 



A bent tube with its orifice exposed to the passing water will, by the 

 height to which the water rises in the tube, indicate the velocity of the 

 vessel or current. 



Tubes of this description have been tried, but the difficulty of ascer- 

 taining the zero point, or the level of the surrounding water fi:om which 

 to measure the height, especially in a boisterous sea and with every vary- 

 ing immersion of the vessel, has hitherto rendered this simple construc- 

 tion unsatisfactory. 



In the instrument now submitted, I overcame this difliculty by using 



