Manchester Mejnoirs, Vol. Iv. (191 1), No. 7- 



VII. The Behaviour of Bodies floating in a Free or 

 a Forced Vortex. 



By Professor A. H. Gibson, D.Sc. 



Uimiersity College, Dundee. 

 Received January iitli. igi i. Read Januaiy 24th. iqii. 



§ I. To anyone who has watched the behaviour 

 of bodies floating in a vortex, whether of dimensions 

 comparable with that of the whirlpool in the Niagara 

 Gorge or such an one as may be formed in stirring one's 

 tea, and who has noted how some objects are apparently 

 irresistibly drawn into the centre of the vortex, while 

 others revolve around its outer boundary, and others 

 again alternately approach and recede from its centre, it 

 must be apparent that the forces producing these various 

 results must be of considerable complexity. 



In a series of experiments recently carried out by the 

 author an attempt has been made to determine how, 

 in either a free or a forced vortex, the behaviour of the 

 object depends upon : — 



{a) Its size, the depth of immersion remaining 

 constant. 



{b) The linear dimensions, in similar objects of the 

 same specific gravity. 



{c) The depth of immersion, in bodies of the same 

 cross sectional area but of different specific 

 gravities. 



{d) The position of the centre of gravity in non- 

 homogeneous bodies of the same size and shape. 



{e) The shape of the body. 



(/") The intensity of the vortex action. 



March yth, igii. 



