[ 249 ] 

 XLIT. On the Motion of Floating Bodies. 



March 4, 1809. 



T SIR > 



JLn your Magazine of the last month, Capt. Burney made 

 certain experiments on unloaded and loaded barges, with re- 

 spect to their velocities in a running stream : and there was 

 an allusion also to beams, or sticks, or timber, always 

 moving with the heavy end foremost. These two problems 

 may be solved in the same way, — they are the result of 

 gravity. The heavier a barge is loaded the quicker will it 

 move, because all water that is in motion moves down 

 an inclined plane seeking its level ; the loaded barge that 

 swims or floats in it will of course move down a regular 

 inclined plane, endeavouring by the force of gravity to de- 

 scend, and its velocity will be in proportion to its weight ; 

 viz. to the quantity of matter moving together ; and unless 

 resisted or opposed by a contrary force, or irregular cur- 

 rents, it will acquire an increased velocity in a certain ratio. 

 This is exactly a parallel case to loaded or unloaded carriages 

 going down hill, the heavier they are, with the greater ve- 

 locity will they press downwards ;— or, to put another case, 

 let a cannon shot and a round piece of turned wood of the 

 same dimensions be rolled down an inclined plane, the can-^ 

 nou ball will roll quickest, because it contains more matter ; 

 jn the same way it would descend quicker through the air. — 

 A beam or stick in the water observes exactly the same laws 

 of matter and motion, and will go down the stream with 

 its heavier end foremost : so kirthe air, if a stick be thrown 

 upwards, the heavier end will first reach the ground. — The 

 savages in the South Sea Islands know this, and make cer- 

 tain short spears or clubs, which they throw at their ene- 

 mies, over wherever they see a crowd of them ; and these 

 clubs fall with the heavy end downmost, and if they hit 

 disable or kill. J am, sir, your obedient servant, 



G. Orr. 

 To Mr. Tilloch. 



xuir. p?o- 



