66 



NA TURE 



[November 20, 1902 



by Owen forty years ago. Now our friends at Berlin are con- 

 gratulating themselves because they have obtained a single 

 individual, and are trying to make out that the animal has 

 never been properly figured ! 



Amongst the recent additions to the Zoological Society's 

 reptile house are several specimens (deposited by the Hon. 

 Walter Rothschild, M.P.) of the very curious large iguanoid 

 lizard (Conolophus subcristatus) which inhabits the central 

 islands of the Galapagos group, and the habits of which were de- 

 scribed by Darwin in his "Naturalist's Voyage " (vol. iii. p. 469). 

 It is a terrestrial species, and is stated by Darwin to be so 

 numerous in certain districts that he and his companions could 

 scarcely find a spot free from their burrows on which to pitch 

 their tent. Closely allied to it is a large marine species of lizard 

 (Amblyrkynchus cristatus), also confined to the Galapagos group, 

 which lives exclusively on the rocky sea-beaches and is said 

 "to go out to sea in shoals to fish." Living examples of the 

 latter species were also brought away by Mr. Beck, Mr. 

 Rothschild's collector, from the Galapagos, but, unfortunately, 

 they did not reach England alive. 



We have received parts xii. and xiii. of the Bulletin of the 

 Geological Commission of Finland, containing papers on the 

 crystalline rocks of the countiy by B. Frosterus, and on a 

 meteorite by W. Ramsay and L. H. Borgstiom. 



The Transactions of the Leicester Literary and Philosophical 

 Society (vol. vii. part i., July, 1902) contain useful geological 

 maps by Mr. Fox Strangways, on the scale of two inches to a 

 mile, illustrating excursions made to parts of the Soar and 

 Wreak valleys ; and there is an instructive infra-Triassic map of 

 Charnwood Forest by l'rof. W. W. Watts. There is also a 

 detailed report, with map, on the geology of the Beaumont Leys 

 Estate, near Leicester, by Mr. Montagu Browne. Geology 

 evidently flourishes in this Society under the enthusiastic leader- 

 ship of Mr. H. A. Roechling. 



From the New Mexico College of Agriculture and Mechanic 

 Arts we have received Bulletins Nos. 42 and 43, in which Mr. 

 J. D. Tinsley deals with the problem of alkali in the soil, and 

 with drainage and flooding for its removal. Sodium carbonate 

 is the essential constituent of " black alkali,'' as it appears to 

 blacken the vegetable matter in the soil ; while other salts of 

 soda, as well as salts of magnesia and lime, help to form what 

 is termed " white alkali" soil. It is pointed out by the author 

 that the alkali is left in the soil by the evaporation of water 

 that has gradually risen to the surface. When this excess of 

 water is removed, the alkali will cease to accumulate and soon 

 be washed out of the soil. 



The latest issue (1900-1901) of the Proceedings of the Royal 

 Physical Society of Edinburgh contains a full report of the 

 presidential address delivered by Mr. B. N. Peach in November, 

 1900, the subject of which is Scottish palaeontology during 

 the last twenty years. Full justice is done to workers in all 

 branches of this science, while special attention is directed to 

 the important service rendered by palaeontological investigations 

 to the task of unravelling the geological sequence in the High- 

 lands. " The work done in Scotland during the period under 

 consideration has thoroughly established the paramount value of 

 palaeontology in the interpretation of the geological structure of 

 the country." 



Dr. G. T. Moody describes a new "laboratory shaking 

 machine " in the Chemical News of November 7. As a shaking 

 machine capable of giving satisfactory results in the laboratory 

 has long been sought by chemists, it is worth while to direct 

 attention to that devised by Dr. Moody. ■ 



NO. 1725, VOL. 67] 



A second enlarged and revised edition of " Das Wachstum 

 des Menschen," by Dr. Franz Daffner, has been published by 

 Mr. W. Engelmann, Leipzig (London : Williams and Norgate). 

 The volume contains many interesting papers on the rate and 

 character of the development of the different parts of the 

 human body from embryonic stages to maturity. 



In the numbers of the Journal of the Society of Arts for 

 October 17, 24, 31 and November 7 are reprinted the four 

 Cantor lectures recently delivered by Dr. R. T. Glazebrook, 

 F.R.S., on "Glass for Optical Purposes." The first lecture 

 deals with the optical purposes for which glass is used and what 

 it is that the glass used has to do. The defects of microscopes 

 and the way in which they are cured or improved, chiefly by 

 means of the use of glass of varying refrangibility and lenses of 

 different curvature, are included in the second lecture; photo- 

 graphic lenses are considered in the third, and lenses for tele- 

 scopes in the fourth lecture. Students of optics will find in the 

 lectures a wealth of accurate and instructive information upon 

 many points of interest. 



Some very interesting observations relative to the cause and 

 nature of radio-activity have been recently made by Messrs. 

 Rutherford and Soddy, an account of which is given in the 

 September number of the Philosophical Magazine. The experi- 

 ments were carried out with thorium compounds, all of which 

 are radio-active. The authors arrive at the conclusion that the 

 greater part of the radio-activity of thorium is due to a non- 

 thorium type of matter, represented symbolically by ThX, 

 possessing distinct chemical properties. The activity of this 

 new type is not permanent, but undergoes a gradual process of 

 decay, the value falling to one half in about four days. The 

 constant radio-activity of thorium is supposed to be maintained 

 by the continuous production of this new type of matter from the 

 thorium compounds. Its rate of production and the rate of decay 

 of its activity appear to be independent of the physical and che- 

 mical conditions of the system. The ThX is capable of exciting 

 radio-activity on surrounding inactive bodies, and about 20 per 

 cent, of the total activity of thorium is due to this action of the 

 ThX. By suitable means, thorium can be freed from both ThX 

 and the excited radio-activity produced by the latter, and then 

 possesses an activity about 25 per cent, of its original value. 

 This latter, the authors believe, is due to a second non-thorium 

 type of matter. 



The additions to the Zoological Society's Gardens during the. 

 past week include two Chacma Baboons ( Cynoccphalus porcarius) 

 from South Africa, presented respectively by Mr. C. S. 

 Blundell and Captain P. J. Probyn, D.S.O. ; a Vervet Monkey 

 (Cercopitheeus lalanciii) from South Africa, presented by Mr. 

 J. II. Kirby ; two Prairie Marmots (Cynomys ludovicianus) from 

 North America, presented by the Countess de Grey ; a 

 White-collared Mangabey (Cereocebus collaris), a Rose-ringed 

 Parrakeet (Palaeornis docilis) from West Africa, deposited ; 

 two Brown Pelicans (Pelecanns fuscus) from the West Indies, 

 received in exchange. 



OUR ASTRONOMICAL COLUMN. . 



Change of Focus in the Light from Nova Persei. 

 — As previously recorded in these columns (July 3), Prof. 

 E. E. Barnard made several determinations, during 1901, of 

 the visual focus of the light from Nova Persei, in order to 

 determine if the presence of the nebula lines in its spectrum 

 produced the difference from stellar focus observed in the case 

 of planetary nebulas ; his observations showed no decided differ- 

 ence of focus. 



Observations made on July 14, August 29; September I and 

 September 16 of this year produced a like negative result, and 



