January 5, 1922] 



NATURE 



23 



but unfortunately rats were accidentally introduced into 

 the island, and the birds' paradise of two years ago 

 has been reduced to a veritable wilderness beyond all 

 hope of recovery. Mr. McCulloch's account of this 

 tragedy is accompanied by excellent photographs and 

 an interesting description of the natural history of the 

 island, with valuable notes on some of the more 

 interesting birds — magpies, woodhens, and mutton- 

 birds. 



In the Journal of the Federated Malay Slates 

 Museums (vol. lo, part 3, June 192 1), Major J. C. 

 Moulton publishes the first of a series of articles on 

 Malaysian butterflies, designed to supplement or cor- 

 rect the information of this region given in Seitz's 

 •' Macrolepidoptera of the World." The author defines 

 a true Malaysian sub-region as distinct from a wider 

 area, in which a non-Malaysian element is evident, 

 though not necessarily predominant, and defines it as 

 between lat. 10° N., and 10° S., and long. 95" K. 

 and 120° E., thus including the Malay Peninsula, 

 Borneo, Sumatra, and Java, with its adjacent islands. 

 Thirteen new forms and combinations are described. 

 Major Moulton continues the innovations introduced 

 into his earlier papers of printing the sub-specific 

 names in less prominent type than the generic and 

 specific names, and of retaining the author's name 

 for a species even when followed by a sub-specific 

 name. Both courses have since received the approval 

 of the British .Association Committee on Zoological 

 Nomenclature. Valuable notes on variations and 

 geographical distribution are given, accompanied by 

 useful keys for the discrimination of species, sub- 

 species, and forms. We may specially note the dis- 

 tinction drawn by the author between "sub-species " 

 and " forms " — the former as geographical races in- 

 habiting separate areas, and the latter as well-defineJ 

 forms occurring together over a wide range of country. 



The difficult question of the drainage of the Vale 

 of Pewsey, a district now so well known to the 

 aviators of Upavon, is dealt with by Mr. W. D. 

 Varney in the Proceedings of the Geologists' Associa- 

 tion, vol. 37', p. 189, 1921. The vale seems to have 

 been excavated originally along th<e Pewsey anti- 

 cline of Cretaceous rocks, which provided a line of 

 weakness, by a river flowing eastward from the Cots- 

 wolds and escaping southward by the present gap 

 of the Avon, the river that passes through Salisbury 

 to the sea at Christchurch. This stream was beheaded 

 during the growth of the Severn valley, when the 

 other Avon of the district, w^hich flows through 

 Bristol, was working its head backwards and cap- 

 turing in addition some of the head-waters of the 

 Kennet and the Thames. Mr. Varney 's sketch-maps 

 indicate also the recession of the southern coastline 

 and the formation of the Isle of Wight. 



In a lengthy and most instructive article in the 

 Geographical Review for October last on the distribu- 

 tion of population Mr. M. Aurousseau directs attention 

 to the fact that three kinds of maps which at present 

 do not exist are much wanted and could be compiled 

 by the geographical survey of countries. The earth- 

 NO. 2723, VOL. 109] 



material map would show the following features : 

 Areas of deep drift soils, areas of residual soils, hydro- 

 graphical information, fuel deposits, and the location 

 and nature of metallic ores and other economic 

 deposits. The power map should show the distribu- 

 tion of the different power resources — wood, wind, 

 water, coal, oil, etc. Finally, the lowlands map would 

 be a topographical map so coloured that the lowlands, 

 even when of small areas as in the case of inter- 

 montane deposits, would stand out prominently. Mr. 

 Aurousseau also points out that in taking stock of 

 the world's resources we require to know the expan- 

 sion ratio of every land — that is to say, the ratio of 

 the extent to which a given area is occupied to the 

 extent to which it may be occupied. He sketches the 

 nature of the geographical survey required in order 

 that this ratio may be obtained. 



An interesting paper on Greek and Roman engineer- 

 ing instruments, read before the Newcomen Society 

 on December 15 last by Mr. R. C. Skyring Walters, 

 illustrates the uses of historical research applied to 

 science. Such research, the product of co-operation 

 between classical scholars and men of science, was 

 also exemplified at a joint meeting of the Textile 

 Institute with the Manchester and District Branch 

 of the Classical Association and Literary and Philo- 

 sophical Society last November, and it cannot fail to 

 be of great usefulness. In his paper Mr. Walters 

 quotes the description by Vitruvius of the use of the 

 dioptra, chorabates, and water levels in surveying by 

 the Greeks and Romans up to about 100 a.d., and 

 he gives sectional drawings showing reconstructions 

 of these instruments, of which no complete example 

 remains. The groma, an arrangement of two crossed 

 arms at right angles with suspended plumb lines at 

 the ends, used for setting out straight lines and lines 

 at right angles, is also shown. In the case of the 

 dioptra the advanced stage of development in con- 

 structive detail which was reached at the time of 

 Hero of Alexandria, is remarkable. The conclusion 

 is that there are many striking points of similarity, 

 not only in the instruments, but also in the methods 

 employed 2000 years ago, with those of the present 

 day. 



We have received an advanqc copy of a Carnegie 

 Research Memoir published by the Iron and Steel 

 Institute on the constitution of chromium steels by 

 Mr. T. F, Russell. During recent years industrial 

 applications of iron-carbon-chromium alloys have in- 

 creased, and a paper on this subject, therefore, is 

 welcome. It must be confessed, however, that the 

 jM"esent one does not do much to advance our know- 

 ledge of chromium steels. The author has confined 

 himself to an examination of a very restricted area 

 of the iron-carbon-chromium ternary system, in which 

 the carbon does not exceed i per cent., while the 

 limit of chromium is 12 per cent. It would have been 

 better if he had taken into consideration in the first 

 instance the equilibrium conditions observed in th»' 

 binarv svstems iron-carbon, chromium-carbon, and 

 iron-chromium. Without this a scientific interpretation 



