November 4, 1920] 



NATURE 



315 



stored in the amorphous cement around the 

 crystals as conceived by Rosenhain, because 

 (i) all the available evidence is against the view 

 that the crystals of castings grow ; (2) the greater 

 the surface area of a crystal the more energy it 

 should possess, and on this view a large crystal 



should absorb a small one. It has been shown 

 that this is by no means always the case. It is 

 considered that until much fuller knowledge of the 

 structure and properties of crystals has been 

 obtained, the true explanation of the effects of 

 work upon metals will not be forthcoming. 



The New Star in Cygnus. 

 By Major W. J. S. Lockver. 



""PHE new star in Cygnus, the third discovered 

 J- in that constellation, and therefore desig- 

 nated Nova Cygni 111., wasof magnitude 35 when 

 first observed by Mr. Denning on August 20, but 

 is now very faint, being below 9th magnitude. It 

 is still visible in small telescopes, but requires 

 large instruments for spectroscopic investigation. 



.\ summary of the earlier part of the star's his- 

 tory — i.e. previous to August 20 

 — is brought together by Mr. 

 Felix de Ray in the current 

 issue of the Observatory (vol. 

 xliii., No. 557, October), and is 

 of great interest. Thus the 

 object was not visible on June 3, 

 1905, when a plate taken of that 

 region showed stars down to the 

 i6th magnitude. On July 20 of 

 the present year another plate 

 taken there recorded stars down 

 to magnitude 1 1 ; but still there 

 was no trace of the nova. A 

 I)hotograph taken at Harvard on 

 August 9, 1920, shows stars to 

 the 9th magnitude, and no nova 

 appears upon it ; but the object 

 was recorded there on August 19, 

 and its magnitude was then 4-8. 

 .\n earlier record than this is 

 given on a plate taken by Nils 

 Tamm in Sweden on August 16 

 of this year, when it was shown 

 as a 7th-magnitude star. 



The above records give an 

 idea of the nature of the rise in 

 magnitude of the nova, and 

 these data (broken lines), com- 

 bined with the excellent scries 

 i)f observations made at Greenwich (con- 

 tinuous lines), and published in the same number 

 of the Observatory (p. 367), enable the light 

 curve of the nova to be constructed. This curve 

 is given in Fig. i. It will be seen that, like all 

 novtc, there is a very rapid rise to maximum bril- 

 liancy, followed for a short period by an almost 

 ai rapid decrease. .After that the decrease is more 

 gradual, but at a quicker rate than is generally 

 the case in later stages of novse. 



It should Ix; remarked that the Greenwich 

 values here recorded arc "smoothed" values — 

 that is, a mean curve has been drawn through the 

 original observed values. This process has the 

 drawback of eliminating any small oscillations of 

 NO. 3fi62, VOL. 106] 



magnitude which may occur in the original curve. 

 Thus on the descending side of the curve there 

 are undoubtedly instances where the nova 

 not merely retained the same magnitude for 

 two consecutive nights, but actually increased in 

 brightness. Such fluctuations were, however, on 

 a very small scale, and nothing like the pro- 

 nounced regular variations which Nova Persei 



AUG. 



SEPT. 



Fig. I. — Th« ligbt curve of Nova Cygni III., illu.sjraling the rapid rifte to maximum and the comi>ara- 

 tively slow descent. The unbroken line is from observations made at Greenwich Observatory. 



presented after it had reached the 4th magnitude, 

 the amplitude of this fluctuation amounting to 

 about one and a half magnitudes in periods of 

 three or four days. 



No less interesting has been the spectroscopic 

 study of this nova. Up to the present time very 

 little has been published on the subject, but no 

 doubt several communications upon it will be 

 made at the November meeting of the Royal 

 Astronomical Society. In Section A of the 

 British Association at the recent meeting: 

 Prof. Fowler showed .some slides taken from 

 negatives secured at the Hill Observatory, 

 Sidmouth, on the night of .August aa, when 

 the nova was approaching its maximum. 



