Dec. 19, 1878] 



NATURE 



157 



Dr. Edwin R. Heath, to whom we referred some 

 time ago as intending to take up the work of South 

 American exploration commenced by Prof. Orton, and 

 interrupted by his untimely death, left New York on 

 November 18, on the William H. Keeney, for Para, ex- 

 pecting to proceed by steamer to San Antonio, to remain 

 there during the winter, and from that point as a centre 

 to carry on his further investigations. In these he ex- 

 pects to be greatly assisted by Messrs. T. and P. Collins, 

 of Philadelphia, the contractors for the Mamore and 

 Madera Railroad. 



The Woodruff half-educational, half-pleasure expe- 

 dition round the world has been again organised on 

 a new basis. A steamer of 3,000 tons has been purchased 

 in Europe, and the inclusive fare is 2,500 dollars. 



Mr. S. E. Peal communicates to the Indian Tea 

 Gazette some remarks on the subject of an overland 

 route to China, via the Assam Valley, which are of 

 interest, as there is no attempt to under-rate the great 

 difficulties to be encountered. He justly observes that 

 the merits of the various passes out of Eastern Assam 

 are not well understood, and that it is comparatively easy 

 to draw a line on the map from some point in Upper 

 Assam to the Yangtoze or Likiang-fu, and to say, " Why 

 cannot this be done?" Wilcox and others since have 

 sufficiently shown the difficult nature of the country, via 

 the Tengapani and the Brahmaputra Valley ; what lies 

 beyond the point explored is reputed still worse, and as 

 crossing snow. Northwards again, via the Dihong, or 

 Dihong Gorges, the outlet is equally uninviting. The 

 Upper Subansire, or Lopra-cha-chu, is not well explored, 

 though routes not far from it are known to pass for three- 

 quarters of a mile along the face of a precipice 1,500 feet 

 above an abyss, and on a path of stone slabs resting on 

 iron piers let into the face of the rock. The Towang 

 route is, again, difficult, and too far west. South 

 of the Tengapani we have Dapha Biim, 14,500 

 feet high, with a pass to the south, in which Wilcox' s 

 experiences prove how unsuitable it would be for j 

 a trade-route. South of Daphapani is the upper por- 

 tion of the Buri Dihing, and whether there is a route up 

 it crossing Eastern Patkai and going down the Sitka, is ■ 

 not known, though Singphus travel that way. It is one 

 of the routes to be explored, and may give a pass at, \ 

 perhaps, 5,000 feet elevation or less. The Namrup basin, ' 

 however, would so far seem to be the only reliable and 

 easy outlet from Eastern Assam : and here is a pass at 

 an elevation of about 1,000 ft., leading vid Hukong and 

 the Shoemai direct to Western Yunnan, a route which is i 

 at present in use. By the Patkai route past Xongjang ! 

 Lake to the Hukong Valley, IMr. Peal says, we cross at the j 

 highest an elevation of 1,500 to 2,000 ft., and fall at once ! 

 mto a beaten track to Yiinnan. By this route alone i 

 also can the huge snow-clad ridges be turned that stand i 

 as barriers east and west of the Upper Irrawadi or \ 

 Shoemai, and that stretch down from the north to about ' 

 the parallel of 27°. In point of fact the east-south-east 

 is tne only direction in which it is possible to get out of 

 Assam m the direction of China at less than 2,000 ft. 

 above the sea-level. 



THE COMPOUND NATURE OF THE . . 



W ELEMENTS 



E have not yet received from the Royal Society the 

 ...^ -.paper read last Thursday by Mr. Lockyer, in 

 whiph J>^' brought forward facts indicating the compound 

 nature of the chemical elements. In the meantime the 

 tollowing article from yesterday's Times may be of 

 interest; it is evidently written by a chemist who was 

 P''f sent waen the paper was read :— 

 t>,« ^ ^ ciowded meeting such as is seldom witnessed of 

 Nnr^°^"^ ^ociety, on Thursday e^-ening last, Mr. I. 

 Norman Lockyer, F.R.S., read a lengthy paper, in which 



he discussed the evidence derived from spectroscopic 

 observation of the sun and stars and from laboratory ex- 

 periments, which has led him to the conclusion that the 

 so-called elements of the chemist are in reality compound 

 bodies. In order that the line of argument followed by 

 Mr. Lockyer may be understood, it will be necessary 

 briefly to refer to the results of previous researches. As 

 a rule, in observing spectra, the substance to be examined 

 is volatilised in a gas flame or by means of sparks from 

 an induction-coil, and the light is allowed to fall on the 

 slit of the spectroscope ; the spectrum is then generally 

 one in which the lines run across the entire field, but by 

 interposing a lens between the spark apparatus and the 

 slit of the spectroscope, Mr. Lockyer was enabled to 

 study the various regions of the heated vapour, and thus 

 to estabhsh the fact, already noted by some previous 

 observers, but to which little attention had been paid, 

 that all the lines in 'the spectrum of the substance vola- 

 tilised did not extend to equal distances from the poles. 

 He then showed by the aid of this method that in the 

 case of alloys containing different proportions of two 

 metals, if the one constituent were present in very small 

 quantity, its spectrum was reduced to its simplest form, 

 the line or lines longest in the spectrum of the pure 

 substance alone appearing, but that on increasing 

 the amount of this constituent its other lines gra- 

 dually appeared in the order of their lengths in the 

 spectrum of the pure substance. Similar obser\-ations 

 were made with compound bodies. It was also noticed 

 that the lines furnished by a particular substance varied 

 not only in length and number, but also in brightness and 

 thickness, according to the relative amount present. 

 Armed with these facts, and with the object of ultimately 

 ascertaining, more definitely than has hitherto been pos- 

 sible, which of the elements are present in the sun, Mr. 

 Lockyer, about four years ago, commenced the prepara- 

 tion of a map of a particular region of the spectra of the 

 metallic elements, for comparison with the map of the 

 same region of the solar spectrum. For this purpose 

 about 2,000 photographs of spectra of all the various 

 metallic elements have been taken, and, in addition, more 

 than 100,000 eye observations hare been made. As it is 

 almost impossible to obtain pure substances, the photo- 

 graphs have been carefully compared, in order to elimi- 

 nate the lines due to impurities ; the absence of a par- 

 ticular element as impurity being regarded as proved if 

 its longest and strongest line was absent from the photo- 

 graph of the element under examination. The result of 

 all this labour, Mr. Lockyer states, is to show that the 

 hypothesis that identical lines in different spectra are due 

 to impurities is not sufficient, for he finds short line co- 

 incidences between the spectra of many metals in which 

 the freedom from mutual impurity has been demonstrate! 

 by the absence of the longest line§. He then adds that, 

 five years ago, he pointed out that there are many facts 

 and many trains of thought suggested by solar and stellar 

 physics which point to another hypothesis — namely, that 

 the elements themselves, or, at all events, some of them, 

 are compound bodies. Thus it would appear that the 

 hotter a star the more simple is its spectrum ; for the 

 brightest, and therefore probably the hottest stars, such 

 as Sirius, furnish spectra showing only very thick hydro- 

 gen lines and a few very thin metallic lines, characteristic 

 of elements of lowatomic weight, while the cooler stars, such 

 as our sun, are shown by their spectra to contain a much 

 larger number of metallic elements than stars such as 

 Sirius, but no non-metallic elements; and the coolest 

 stars furnish fluted band-spectra characteristic of com- 

 pounds of metallic with non-metallic elements and of 

 non-metallic elements. These facts appear to meet with 

 a simple explanation if it be supposed that as the tem- 

 perature increases the compounds are first broken up 

 into their constituent "elements," and that these "ele- 

 ments" then undergo dissociation or decomposition into 



