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XXXVIII.— NOTE ON DUST KEPULSION. By GEOEGE 

 FEANOIS FITZGEEALD, A.M., F.T.C.D. 



[Read, Jiine 5, 1884.] 



Dr. Oliver J. Lodge has pointed out that when a body is warmer 

 than dusty air in its neighbourhood, the dust has a tendency not to 

 settle on it. When speaking to him on the subject he did not 

 seem to have been aware of Prof. 0. Reynolds' experiments on the 

 motion of silk fibres suspended in air and subject to radiation/ 

 which Professor 0. Reynolds explains by the absorption of the 

 radiations by the silk, and the consequent polarization of the air, 

 warmed by contact with the small fibres, producing an apparent 

 repulsion of the fibre. Professor 0. Reynolds' theory of the 

 radiometer points to the conclusion that very small bodies would 

 act in dense air in the same way as the comparatively large vanes 

 of a radiometer do in rare air. This application of Professor 0. 

 Reynolds' theory to explain the tendency of the warmth of a body 

 to prevent dust settling on it seemed very obvious, and occurred to 

 me immediately I heard of the experiments of Dr. Lodge, and I 

 would not have thought it worth while mentioning only that I 

 found that Dr. Lodge himself did not seem to have noticed it. 



1 Phil. Trans. E. S., 1879, part ii. On Certain Dimensional Properties of Matter in 



the Gaseous State. 



