THE 

 LONDON, EDINBURQH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



FEBRUARY 1878. 



XIV. An Account of some Experiments on Rigidity produced by 

 Centrifugal Force. * By John Aitken, F.R.S.E.} 

 [Plates IIL-VIL] 

 TP-HE experiments do not contain much that is new, many 

 J- of the problems having previously been mathematically 

 wrought out by Sir William Thomson and others. They, 

 however, help to fill up a very evident gap in our experimental 

 dynamics ; and it is hoped they will enable the general reader 

 to form a clearer idea of the action of the so-called centrifugal 

 force, a force the fundamental action of which is often mis- 

 understood. This tendency to misunderstanding has arisen 

 principally from two causes : — the one being the paucity of 

 our experimental . illustrations of centrifugal force (almost 

 all our experiments only illustrate the action of this force 

 round one centre and in one plane); the other cause being 

 the name which has been applied to this force, the word centri- 

 fugal meaning " to fly from the centre," which has given rise 

 to the idea that there is a force acting on a body when revolving 

 round a centre tending to cause it to fly away from that 

 centre. If some word more correctly expressive of the action of 

 this force could be introduced, it would do much to remove 

 the present confusion. Professor James Thomson, in a paper 

 before the British Association at Glasgow in 1876, objects to 

 the word centrifugal, and only retains it on account of its very 



* [The experiments were in part communicated to the Royal Society, 

 Edinburgh, and also in part to the Philosophical Society of Glasgow, 

 during the session 1875-76, and slight accounts published in the Proceedings 

 of those Societies. A complete account, with drawings of the apparatus, 

 is now published for the first time. — W. T.] 



t Communicated by Sir W. Thomson, Dec. 1877. 



Phil. Mag. S. 5. Vol. 5. No. 29. Feb. 1878. G 



