On floating Bodies. 301 



for in the former case the bodies move through a medium 

 which is perfectly at rest ; and in the latter the medium it- 

 self is in motion, and is the cause of the motion of the 

 bodies. 



Having thus, I think, satisfactorily shown that Mr. Orr's 

 laws of matter and motion are not sufficient to account for 

 the circumstance alluded to by Capt. Burney, I will venture 

 to offer mv own conjectures on this subject ; — but this I do 

 with considerable diffidence, and soliciting a correction of 

 any errors that may be discovered therein by any of your 

 ingenious correspondents. 



Let us then suppose the case of a beam of timber loaded 

 at one end ; and let us conceive that in the first instance the 

 beam moves parallel to itself, or that the velocities of the 

 two ends are equal : then it is evident that the heaviest end 

 will acquire the greatest momentum, and consequently, if 

 the beam should experience any resistance in its motion, 

 that end of it which possesses the greatest momentum will 

 oppose that resistance with the greatest effect, and will thus 

 be thrown foremost ; and this will continue to be the case, 

 till its direction coincide with that of the stream. 



What the resistance is that the beam experiences, and 

 from what cause it arises, are not difficult to determine. In 

 such a river as the Thames, where the experiments were 

 made, and where the tide is constantly ebbing and flowing, 

 every particle of water cannot be supposed to move with 

 equai velocities; small eddies, contrary currents, and va- 

 rious other circumstances will prevent that uniformitv, 

 though perhaps they may be imperceptible to the eye of even 

 an attentive observer. This being the case, if the beam 

 should be struck by any particles of water moving in a con- 

 trary direction, or should the beam strike any that are at 

 rest, or moving in the same direction as itself, but with a 

 less velocity, any of these circumstances will oppose a re- 

 sistance to the motion of the b< am, which it has been shown 

 will be more effectively overcome by that end of it which 

 has the greatest momentum. And in a similar manner we 

 aiav account for the motion of the two barges. 



Should 



