358 On holding the Breath for a lengthened Period. [1833. 



of an infinity of systems of waves polarized (i. e. vibrating 

 transversely) in all azimuths, and so, that there is as much 

 polarized light in any one plane as in a plane perpendicular to 

 it." Herschel says that Fresnel supposes the eye to be 

 affected only by such vibrating motions of the etherial mole- 

 cules as are performed in planes perpendicular to the direction 

 of the rays. Now the effects in question seem to indicate how 

 the direct vibration of the luminous body may communicate 

 transversal vibration in every azimuth to the molecules of 

 the ether, and so account for that condition of it which is 

 required to explain the phenomena. 



129. When the star of ridges formed by a vibrating cylinder 

 (119) upon the surface of water is witnessed instead of the 

 series of circular waves that might be expected, it seems like 

 the instant production of the phenomena of radiation by means 

 of vibratory action. Whether the contiguous rarefied and con- 

 densed portions which I have supposed in air, gases, vapour 

 and the ether, are arranged radially like the ridges in the 

 experiment just quoted, or whether rare and dense alternate 

 in the direction of the radii as well as laterally, is a question 

 which may perhaps deserve investigation by experiment or 

 calculation. 



Royal Institution, July 30th, 1831. 



Notice of a Means of preparing the Organs of Respiration, 

 so as considerably to extend the Time of holding the Breath ; 

 with Remarks on its Application in Cases in which it is 

 required to enter an irrespirable Atmosphere, and on the 

 Precautions necessary to be observed in such Cases*. 



To the Editors of the Philosophical Magazine and Journal. 



GENTLEMEN, There are many facts which present themselves 

 to observant men, which, though seen by them to be cu- 

 rious, interesting, and new to the world, are not considered 

 worthy of distinct publication. I have often felt this conclu- 

 sion to be objectionable, and am convinced that it is better to 

 publish such facts, and even known facts under new forms, pro* 

 vided it be done briefly, clearly, and with no mere pretension 

 * Philosophical Magazine, 1833, vol. iii. p. 241. 



