S4 Oh Floating Bodies, ^c. 



tribiited why one ship sails better than anothet*, andl 

 which, on some future occasion, 1 may attempt to demon-* 

 Btrate. 



Timber used at sea to find the direction of any current 

 ought to be in its shape conical, and a good deal so, but 

 the base of the cone to be rounded, or the sharp angles laken 

 off, in order that it may pass more fairly through the water; 

 for wood of this fhape vviil take the direction better, and 

 be more easily observed : in such cases there should always 

 be two conical timbers, and if they both take the same di- 

 rection, the tendency of the current is certainly proved. 

 No experiments can be made on this subject with South 

 Sea clubs, such as captain B. used, nor with anything 

 that will sink in water, 'that is, with any body specifically 

 heavier than water. 



Supposing a barge loaded at one end and empty at the 

 other, and without a helm, if it floated in a fair and regu- 

 lar stream without currents, it would certainly proceed 

 with the heavy end foremost, for the same reasons that a 

 conical piece of wood, or even a cylindrical one loaded at 

 one end, would go with their heavy end foremost in a 

 fluid, though originally placed in a contrary direction : it 

 would be the same with the cone and cylinder, if placed 

 across a dry inclined plane ; that end containing the greatest 

 quantity of matter, from its pov\er of overcoming resist- 

 ance, would always have a tendency to be foremost. The 

 inclined plane of rivers and streams must, from the number 

 of inequalities at bottom, be a very irregular one — the cur- 

 rent will partake of those irregularities, and the motion of 

 bodies that float in them must be affected by them in a cer- 

 tain degree. 



Lastly, Does a body floating down a stream or current, 

 and which has a quicker progress than the stream or cur- 

 rent, receive any addition to its motion from the motion 

 of the fluid ? I think it docs not ; that it is only indebted 

 to the fluid for its suspension, but that it is to its own 

 gravity, and acting in one mass, that it is indebted for its 

 greater progress. On the contrary, I think it loses in its 

 velocity or progressive motion ; for though the floating 

 body be specifically lighter than the water, and of course 

 one would imagine that it would move slower, still, owir>g 

 to the causes already enumerated, its progress is quicker : 

 but there is a drawback on this progress ; because, if the 

 solid overtake the water, part of its force must be wasted 

 against that body which moves slower, but in the same di- 

 fccliou. This cai» »6 analogous to that of two balls moving 



ivi 



