April I, 1886] 



NATURE 



The author, from his position as Medical Director for the 

 province of Semiretchie, where the Kirghis population numbers 

 more tlian 550,000, has had exceptional opportunities for 

 observing the social and doniestic habits of the people ; and his 

 carefully-conducted craniometric and other measurements, to- 

 gether with his exhaustive remarks on the physical, moral, and 

 intellectual characteristics of the people, their language and 

 literalure, religion and superstitions, and the past and probable 

 future efl'ects on the race of closer contact with Western civilisa- 

 tion, supply valuable materials towards the history of these 

 ancient tribes, whose numbers are computed at upwards of a 

 million and a half. — On the so-called cup-like excavations, 

 " Pierres a Cupules," by M. de NadaiUac. The author pisses 

 in review the most remarkable of these stone-markings, which 

 have been found in the most widely-separated parts of the globe 

 since they first attracted notice in Switzerland in 1849. In 

 Brittany, where such stone- markings and depressions have of 

 late years been found in great numbers, they appear to be con- 

 temporaneous with the dolmen age. M. de Nadaillac is of 

 opinion that the general similarity of the markings, of which he 

 gives various clear drawings, cannot be accepted as a proof of 

 any ethnic connection between the various peoples who designed 

 them, and is probably only to be referred to a general similarity 

 of intelligence among men at one and the same stage of their 

 respective courses of development. — Contributions to the history 

 of muscular anomalies, by A!. Ledouble. In the present paper, 

 which is a sequel to the author's articles in last year's Rcz'ue on 

 the major and minor pectorals, he treats specially of the varia- 

 tions of length and breadth in the abdominal muscles, con- 

 sidering each anomaly from a comparative anatomical point of 

 view. 



SOCIETIES AND ACADEMIES 



London 



Royal Society, January 28. — "On the Development of 

 the Cranial Nerves of the Newt." By Alice Johnson, Demon- 

 strator of Biology, Newnham College, Cambridge, and Lilian 

 Sheldon, Bathurst Student, Newnham College, Cambridge. 

 Communicated by Prof M. Foster, Sec. R.S. 



February 25. — "On Radiant Matter Spectroscopy: Note on 

 the Earth Ya." By William Crookes, F.R.S. 



Among the samarskite earths which concentrate towards the 

 middle of the fractionations there is one (or a group) which pre- 

 sents in the radiant matter tube a well-marked phosphorescent 

 spectrum differing from those I have already described. 



The measurements of the bands and lines are given below : — 



Scale of 



spectroscope 



Remarks 



io'325 6446 2407 Approximatecentreof ared band 

 shaded off on the least refran- 

 gible side. 



iO'3io 6415 2430 Somewhat sharp edge of the red 

 band. 



10TS5 61S9 261 1 Approximate centre ot a very 

 faint orange band. 



I0'I30 6094 2693 A sharp narrow orange-red line. 



I0'05 5970 2806 Approximate centre of a narrow 



bright orange band. ( Between 



this line and 2693 is a fainter 



scmi-contipuous orange band). 



9 '840 5676 3104 Approximate centre of a narrow 



bright green band. 

 9790 5613 3174 Approximate centre of a narrow 

 green band, not quite so bright 

 as 3104. 

 9-690 5495 3312 Approximate centre of a bright 

 green band, wider than the 

 other three green bands. 

 9610 54°6 3422 Approximate centre of a narrow 

 bright green band. 



The earth giving the above spectrum, when sufficiently puri- 

 fied, presents all the characteristics of the earth discovered by 

 Marignac, and provisionally called by him Ya (Coinptes rendus, 

 xc. p. 899). Through the kindness of M. de Marignac I have 

 1 een enabled to compare a specimen of Ya of his own prepara- 



tion with the earth described above. The two earths agree in 

 their chemical characteristics, and their phosphorescent spectra 

 are practically identical. 



No name has yet been given to this earth, as the discoverer 

 appears to be in some doubt whether it is not identical with J. 

 Lawrence Smith's earth mosandra {Comptes rauius, Ixxxvii. p. 

 145 ; Ixxxvii. p. 831 ; Ixxxix. p. 4S0). A specimen of mosandra 

 prepared by J. Lawrence Smith, and sent me by M. de Marignac, 

 gave a phosphorescent spectrum showing that it was compound, 

 and that yttria was one of its constituents. 



-"On a Comparison between Apparent Inequalities of Short 

 Period in Sunspot Areas and in Diurnal Declination Ranges at 

 Toronto and at Prague." By Prof Balfour Stewart, F.R.S. , 

 and William Lant Carpenter, B.A., B.Sc. 



The authors discuss these inequalities in precisely the same 

 manner in which they discussed those of a previous communica- 

 tion (Proc. Roy. Soc, vol. xxxvii. p. 290), and are led to the 

 following conclusions ; — 



(ct) When disturbances are excluded as much as possible, both 

 the Toronto and the Prague declination inequalities exhibit signs 

 of duplicity of phase, the predominant maximum at both 

 observatories occurring shortly after the sunspot maximum for 

 inequalities around t«enty-four days. 



(S) On the other hand, for inequalities around twenty-six 

 days the predominant maximum for both observatories more 

 nearly coincides in time with the subsidiary maximum of the 

 twenty-four day inequalities. 



(7) The short-period inequalities of this paper are as nearly as 

 possible equally developed and equally traceable for temperature 

 and for declination ranges. 



(S) When disturbances are excluded as much as possible, 

 corresponding phases appear to take place at Toronto three or 

 four days before they take place at Prague. 



March 4. — The Bakerian Lecture. — "Colour Photometry." 

 By Capt. W. de W. Abney, F.R.S., and Major-Gen. Festing, 

 K.E. 



One of the authors of this paper has already communicated 

 to the Physical Society of London [Phil. Mag. 1885) a method 

 by which a patch of monochromatic light can be thrown on a 

 screen. This formed the starting-point of the present investi- 

 gation, which was to ascertain whether it was practicable to 

 compare with each other the intensity of lights of different 

 colours. 



The authors describe various plans they adopted to effect this 

 purpose, and finally found that, by placing a rod in front of the 

 patch of monochromatic light, and by casting another shadow by 

 means of a candle alongside the first shadow, the intensities of the 

 two lights which illuminated the two shadows could be com- 

 pared by what they term an oscillation method. It is known 

 that on each side of the yellow of the spectrum the luminosity 

 more or less rapidly decreases. By placing a candle at sucli a 

 distance from the screen that the luminosity of the two shadows 

 appears as approximately equal, it is easy to oscillate the card 

 carrying the slit through which the monochromatic rays of the 

 spectrum pass. (The slit is in the focus of the lens which helps 

 to form the spectrum.) The shadow of the rod cast by the 

 candle can thus be made to appear alternately "too light" cr 

 "too dark" in comparison with the shadow of the rod cast by 

 the parts of the spectrum falling on the screen. By a moderately 

 rapid oscillation the position of equality of the two shadows 

 can be distinguished with great exactness. The auth m- describe 

 their method of fixing the position of the rays emp' • ed and 

 the source of light with which the spectrum is formed. 1 hey 

 also enter into details as to the comparison light, the receiving 

 screen, and the comparative value of the light as seen 1 y the 11 

 respectively. The curve of the intensity of the sp'ctrum of 

 the light emitted from the positive pole of the aic light as 

 seen by their eyes, which they call the normal curve, is then 

 described. The question as to the effect of aa alteration of 

 the colour of the comparison light is then discussed, as is the 

 effect of the brightness of the spectrum. 



The next pomt touched upon is as to the value of mixed light 

 as compared with its components. It is found that the following 

 law holds good, viz. : that " the sum of the intensities of tivo or 

 more colours is equal to the intensity of the same rays when 

 mixed." This law is applied to Hering's theory of colour. 



The authors next state that with the majority of people the 

 curve of luminosity of the spectrum is identical with the normal 

 curve, but that in some cases slight differences may be observed, 

 of which one example is given. Such slight deficiency does not 



