EXPERIMENTS ON CURRENTS. £a 



IX. 



Observations on the Progress of Bodies floating in a Stream: 

 with an Account of some Experiments made in the River 

 Thames, with a View to discover a Method for ascertain-' 

 ing the Direction of Currents. By James Burney, 

 Esq. 



AVING frequently noticed, that the heavy craft on Heavy bodies 



the River Thames, during a calm and without the assist- 



float down 



stream faster 



ance of oars or of towing, made a progress faster than the than the cur- 

 stream of the tide on the surface, it led me to make inquiry ,ent * 

 as well into the fact as concerning the cause, and gave rise 

 to some experiments, which, with the ideas they suggested, 

 are here set down ; no otherwise according to method than 

 being in the order they occurred. 



On questioning the men belonging to several barges, Laden barges 

 which, unaided by wind, oar, or towing, were floating with A' at faster than 

 and overtaking the stream, they all agreed in the general 

 fact, as a circumstance familiar to them. They said like- 

 wise, that a laden barge made greater progress than a light 

 barge; and this was corroborated by the evidence of the 

 boats attached to them being drawn after them ; for the 

 barges overtook the moving water so fast as to have good 

 steerage way. They attributed the difference in favour of 

 a laden barge, to her having (as they expressed it) more 

 hold of the tide than a light barge: by which it appear*, 

 that they supposed the stream of the tide was stronger un- 

 derneath than on the surface. Adhesion to the atmosphere 

 may retard the surface, except when the current of the 

 atmosphere (the wind) goes in the same direction with the 

 current of the tide; and then it may occasion an accelera- 

 tion. 



Monday, July the 18th, I went on board a barge half This is not ow« 

 laden, which was floating down the river, but with steerage ing to \ more 

 way, between Putney and Chelsea bridges. I conjectured cunem. 

 the rate of the tide to be a mile and a half per hour : there 

 was a very light air of wind in a direction contrary to the 



Vol. XXIV— Sbft. ISOy. E stream 



