186 



SCIENCE. 



[N. S. Vol. XVIII. Xo. 449. 



CLIMATE AISD RAILROADING. -< 



As the subject of a thesis in the course in 

 General Climatology in Harvard University, 

 Mr. Robert M. Brown took ' Climatic Factors 

 in Railroad Construction and Operation,' and 

 some of the results of the study are em.bodied 

 in an article under the above title in a recent 

 number of the Journal of Geography (Vol. 

 II., pp. 178-190). For purposes of classifica- 

 tion the different districts of the world are 

 arbitrarily grouped as regions of heavy pre- 

 cipitation; of moderate precipitation; of light 

 precipitation; of high altitudes and of severe 

 winters. In each of these regions there are 

 climatic difficulties which must be solved by 

 the engineers and operating officials during 

 construction, and after the road has been built. 

 Where the rainfall is heavy there is decay of 

 ties, sleepers and bridges ; there are floods and 

 landslides. In regions of light rainfall there 

 is great danger of fire; water must be piped 

 for long distances or else carried in tanks; 

 labor is often difiicult on account of the heat; 

 sand is blown by the wind, accumulating on 

 the rails, blinding the drivers, and injuring 

 the machinery. When the altitude is high, 

 mountain sickness, snow blockades and snow- 

 slides must be overcome. In regions of se- 

 vere winters ice breakers may be needed to 

 keep open lakes and rivers, or temporary rails 

 may be laid on the ice; snow and ice hinder 

 construction and operation, and the number 

 of working days may be seriously reduced. 

 Mr. Brown mentions specific instances to il- 

 lustrate these various climatic controls, and 

 the article is a distinct contribution, albeit 

 an incomplete study in itself, on the human 

 side of climatology. It so happens that three 

 railroads now building, or projected, furnish 

 numerous excellent examples of the kind of 

 control considered in Mr. Brown's paper. 

 These are the proposed Trans-Canada and 

 Trans-Australian lines, and the Uganda Rail- 

 way. The former is interesting because of 

 the high latitudes which it is to traverse; the 

 second, because its route lies across the central 

 arid portion of Australia, and the third by 

 reason of its being in tropical Africa. 



R. DeO. Ward. 



Harvard Universitt. 



RADIUM AND HELIUM. 



A PAPER bearing in a remarkable way on the 

 connection between these two elements, which 

 is now exciting so much interest, has been re- 

 ceived for publication by the Royal Society 

 from Sir W. and Lady Huggins. Prompted, 

 in fact, by theoretical ideas, they attacked the 

 problem of the spectroscopic analysis of the 

 light emitted directly by a radium salt at 

 ordinary temperatures. Preliminary visual 

 observation seemed to show traces of bright 

 lines in a continuous spectrum. Preparations 

 were accordingly made for photographic rec- 

 ord by means of a small quartz spectroscope 

 constructed some years ago for use on very 

 faint celestial objects. After several trials, 

 a spectrum, consisting of eight definite bright 

 lines in the • ultra-violet, entirely different 

 from the spark spectrum of radium, and some 

 faint lines together with a very faint con- 

 tinuous spectrum, was obtained by 72 hours' 

 exposure to the glow. The lines were of some 

 breadth, on account of the wide slit that had 

 to be employed in order to admit sufficient 

 light; but it was found possible to measure 

 their wave lengths within an error of two in 

 the fourth figure. On a comparison of this 

 spectrum, so different in type from an ordi- 

 nary phosphorescent spectrum, with the re- 

 corded measurements for helium, it appeared 

 at once that four, .and perhaps five, of the 

 eight lines agreed with lines of helium within 

 the uncertainty of the measurements. An- 

 other line, that of the highest refrangibility, 

 agTees with a line in the spark spectrum of 

 radium itself, which, however, has not been 

 recorded by other observers; the two other 

 lines, the lowest, have not yet been traced. 



It will be remembered that last year Pro- 

 fessor Rutherford produced striking evidence 

 for the view that, in the very slow break-up 

 of radium that is concomitant with its radio- 

 activity, the inert gas helium is one of the 

 products formed. Recently Sir W. Ramsay 

 and Mr. F. Soddy have succeeded in detecting 

 helium by the spectroscope in the gases ex- 

 tracted from a radium salt. If, as the present 

 observations indicate, the radium salt shines 

 spontaneously in the dark largely by light be- 

 longing to the difl'erent element helium, an- 



