MancJiestcr Mcvioirs, Vol. Iv. (1911), No. 7. 3 



under heads varying from 8 to 12 inches, showed this to 

 be sensibly independent of the head, and to have 

 value of '287 in the lin. orifice and '178 in the iMn. orifice. 

 The accompanying tables detail the behaviour of the 

 floating bodies in typical cases of the experiments of each 

 series. 



The following appear to be the main conclusions to 

 be drawn from the free vortex experiments. 



(a) Floating particles whose dimensions are very 

 small compared with those of the orifice, rotate 

 in spiral paths approaching with a continually 

 increasing velocity, and finally disappearing down 

 the funnel of the vortex. The rate of approach 

 of such particles is sensibly the same as that of 

 the fluid itself. (In the second series of experi- 

 ments such particles, of sawdust, described about 

 40 revolutions while approaching the centre from 

 9 inches radius.) The lighter particles, however, 

 show a distinct tendency to approach the centre 

 more rapidly than those of a higher specific 

 gravity. 



((^) If of dimensions which are moderate compared with 

 those of the vortex, the behaviour depends largely 

 on the shape, size, weight, and position of 

 the centre of gravity of the object. In every case 

 the latter rotates, about its own axis, relative to 

 the surrounding water, in the opposite direction 

 to that of its revolution around the centre of the 

 vortex. If introduced near the periphery of the 

 vessel it usually approaches the centre, and may 

 either settle down to rotate in seeming equili- 

 brium at some definite radius,alternately approach 

 and recede from the centre, or straightway dis- 

 appear down the funnel. 



