Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume IV (1876-1877)
Davies, J. E.
Report on recent progress in theoretical physics, pp. 241-264 PDF (6.7 MB)
Recent Progress in Theoretical Physics. 241 REPORT ON RECENT PROGRESS IN THEORETICAL PHYSICS. By J. E. DAVIES, A. M., M. D., Professor of Physics in the University of Wisconsin. PART II. THE MAGNETIC ROTATORY POLARIZATION OF LIGHT. it is a well known fact that a ray of plane polarized light, vibrating in any azimuth, will, on passing through a lamina of quartz, have the azimuth of that vibration changed by an amount depending upon the thickness of the lamina and the wave length of the particular kind of light employed. The direction, right or left, of this rotation of the plane of vibration depends upon the NOTE TO PREVIOUS PAPER ON "VORTEX MOTION." For the production of large-sized vortex rings, the device shown in Fig. 1 is used by Prof. Tait. It is an ordinary wooden box, with a large circular hole cut out of one end, and the other covered tightly with elastic cloth. It can be filled with smoke from a - -~~~~--, ~ ~ ~ ~ ~ couple of retorts, 0 one containing Ammonia and the \\\~\\\\\i\\º\\\ \\\\\\\\other Hydrochlor- ic Acid. This will I I II ~~~~give copious clouds of chloride of Ammonium, Tigs 'which are driven outjin vortex rings, on striking the elastic cloth. It has been objected that the rings thus produced do not behave as Helmholtz' mathematical results imply. It is not to be expected that they should; for Helmholtz' investiga- tion upon vortex motion expressly assumes that the medium in which the rings are formed is afi-ictionless fluid, which air is not. The rings are truly air rings, the accompanying smoke merely serving to make them visible. This is finely shown by sending air rings from a second box against the smoke rings already formed. The invisible air rings are made manifest by the jostling of the smoke rings as they are struck by them. The suddenness of this movement is often very striking. 16
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