Page:Proceedings of the Royal Society of London Vol 69.djvu/370

354 II. " The Specific Volumes of Oxygen and Nitrogen Vapour at the Boiling Point of Oxygen," By Professor J. DEWAR, F.R.S.

III. " The Distribution of Magnetism as affected by Induced Currents in an Iron Cylinder when rotated in a Magnetic Field." By Professor ERNEST WILSON. Communicated by Sir WILLIAM PREECE, K.C.B., F.R.S.

In the first two papers* which I communicated to the Royal Society on the observations of Nova Persei at Kensington, a general descrip- tion of the spectrum in its earliest stages was given, and also a state- ment as to the probable origins of some of the strongest lines, depending upon a comparison of the Nova Spectrum with those of a Cygni, a Canis Majoris. 7 Orionis, &c.

A table showing the results of the detailed reduction and discussion of the bright lines in the best spectrum typical of the Nova in this early stage (that obtained with the G-inch objective prism on February 25, when the star was nearly as bright as Capella), was undertaken later for inclusion in a general summary of the observations in course of preparation.

As various conclusions as to the chemical origin of some of the Nova lines have recently been published which differ widely from those arrived at from a careful study of the Kensington photographs, I think it desirable to publish the above-mentioned table at once. A detailed statement of the evidence on which these conclusions as to origin are based, will follow in the general summary before referred to.

That many of the stronger lines in the early spectra of Nova Aurigse were chromospheric, has been pointed out by several observers, and all agree that there is little difference in the general aspect of the spectrum of Nova Aurigse arid that of Nova Persei at a correspond- ing stage of development. In confirmation of this it may be said that by means of direct comparison of the various Kensington photographs, the identity of most of the strong bright Nova bands with lines of a Cygni and the chromosphere already known to be due to enhanced lines of certain metals has been established.

With regard to the stellar relations of the Nova, I may state that in my note of February 28, t the agreement in position of its lines with

t ' Hoy. Soc. Proc.,' vol. 68, p. 121.
 * ' Roy. Soc. Proc.,' vol. 68, p. 119 and p. 142.