May 1 8, 1SS2] 



NATURE 



63 



nating mines ; it describes the apparatus employed by 

 him, and the difficulties that prevented its practical appli- 

 cation, and continues as follows : — 



" I substituted the voltaic ignition of a platina wire for 

 the disruptive discharge. Any one who has seen the 

 common lecture-table experiment of igniting a platina 

 wire by the voltaic current nearly to the point of fusion, 

 will have no doubt of the brilliancy of the light emitted ; 

 although inferior to that of the voltaic arc, yet it is too 

 intense for the naked eye to support, and amply sufficient 

 for the miner to work by. My plan was then to ignite a 

 coil of platinum wire as near to the point of fusion as was 

 practicable, in a closed vessel of atmospheric air, or other 

 gas, and the following was one of the apparatus which I 

 used for this purpose, and by the light of which I have 

 experimented and read for hours : — A coil of platinum 

 wire is attached to two copper wires, the lower parts of 

 which, or those most distant from the platinum, are well 

 varnished ; these are fixed erect in a glass of distilled 

 water, and another cylindrical glass closed at the upper 

 end is inverted over them, so that its open mouth rests 

 on the bottom of the former glass ; the projecting ends 

 of the copper wires are connected with a voltaic battery 

 (two or three pairs of the nitric acid combination), and 

 the ignited wire now gives a steady light, which continues 

 without any alteration or inconvenience as long as the 

 battery continues constant, the length of time being of 

 course dependent upon the quantity of the electrolyte in 

 the battery cells. Instead of making the wires pass 

 through water, they may be fixed to metallic cups well- 

 luted to the necks of a glass globe. 



The spirals of the helix should be as nearly approxi- 

 mated as possible, as each aids by its heat that of its 

 neighbour, or rather diminishes the cooling effect of the 

 gaseous atmosphere ; the wire should not be too fine, as 

 it would not then become fully ignited ; nor too large, as 

 it would not offer sufficient resistance, and would consume 

 too rapidly the battery constituents ; for the same reason, 

 i.e. increased resistance, it should be as long as the 

 battery is capable of igniting to a full incandescence." 



The memoir concludes with the description of experi- 

 ments on the illumination power of this contrivance 

 under different conditions. 



THE ENGLISH ECLIPSE EXPEDITION 



'THE following communication, under date lat. N. 37 '8, 



-*■ long. E. irjo, April 27, has appeared in the Daily 



News, from the special correspondent of that paper with 



the English Eclipse Expedition : — 



Your correspondent so far has not had a very easy- 

 time of it, although it must be confessed his difficulties 

 have been in no way connected with lack of material. 

 Chronicling attempt- to advance beyond the frontiers of 

 the known must always be a pleasant task to the 

 chronicler, who is thus enabled to be among the first to 

 reap the rich intellectual rewards always gained, or nearly 

 always gained, in such forays. But when the task brings 

 him in full view of other interests, and especially when it 

 compels him to observe phenomena for himself, a corre- 

 spondent's task may become complicated beyond measure, 

 and not only the embarras de richesses, but even a mental 

 revision of his instructions, however precise they may 

 have been, may give him trouble. Thus, in the present 

 case, my clear duty is to keep pace with the thoughts and 

 doings of the Eclipse party now on the Kaisat-i-Hinti, 

 between Gibraltar and Malta ; but am 1 therefore to be 

 blind to the fact that each P. and O. ship does not leave 

 Gravesend with two tons of telescopes and eyes to use 

 them, and that the infusion of a scientific party into the 

 general run of passengers on this the most important of 

 England's seaways, cannot but cause what our American 

 cousins would call a " ripple " on the ordinary routine of 

 ship-life. 



Those who have made their way to the far East many 

 times, and who are therefore quite familiar with this 

 routine, will at once recognise the possibility that at first 

 such rara aves were looked at askance. Was there not 

 at least some strange power of divining secrets in sextants, 

 spectroscopes, and cameras brought now and then, and 

 with a kind of furtive air, from hidden recesses ? And 

 this being so, what conduct was more natural on the part 

 of the non-scientific members of the party, than that they 

 should show a keen anxiety to assure everybody that they 

 at least knew next to nothing of science — in short, that 

 though they might deplore these strange and aberrant 

 tendencies, they were powerless to interfere, even if the 

 studies were less harmless than they believed them to be. 

 This, at first, of course confirmed the general impression, 

 but it did not take long for the ice to melt ; the strange 

 feeling soon wore off, and after a fierce gale which the 

 Kaisar-i-Hind encountered in the Bay of Biscay had 

 abated, the keenness of everybody on board to hear 

 something of a world of marvels new to most of them, 

 and the anxiety of every servant of the P. and O. 

 Company, from captain to boatswain, to help, whenever 

 help was needed, were the predominant features. 



The delight of the Somali boys at being photographed 

 was a sight to see, their broad grins being in strange con- 

 trast with the evident anxiety of the Arabs among the 

 crew to escape the influence of such a possible evil eye. 

 While this is going on in one part of the ship, the reflec- 

 tion of the summer sun shimmering from a thousand 

 Mediterranean waves through which the noble ship 

 ploughs her way on an even keel is utilised to show the 

 wondrous work which has already been done by the 

 spectroscope. Nor are the other worlds, still left to 

 conquer, forgotten in the demonstration ; among them, 

 those secrets of the Sun which it is hoped may be un- 

 veiled during the coming precious seventy seconds. And 

 this brings me to the proper subject matter of the present 

 letter. What, then, are the astronomers going to do? or, 

 to put it more modestly, what are they going to try to 

 do? Before a categorical answer can be given to this 

 question there is some preliminary matter to be got over ; 

 we have, in fact, to consider the changes in thought and 

 methods introduced by ten years of work. A volume 

 might be written on this, but a very brief expose is really 

 all that is required on the present occasion. The bril- 

 liant achievements of physical astronomers in the domain 

 of solar physics during the last twenty years have dealt 

 in the main with the chemical and physical construction 

 of the atmosphere of our central luminary ; that is, those 

 parts of it which are furthest from the centre. In fact, it 

 has been a question of meteorology, and not a question of 

 geology, to use terrestrial equivalents. One of the first 

 things made absolutely certain was that the outer atmo- 

 sphere for tens and perhaps hundreds of thousands of 

 miles above the surface of the round orb we generally see 

 and call the Sun, is intensely hot — hot enough to have its 

 clouds built up of vapour of iron, as in our own air we 

 have clouds built up of the vapour of water. Next, as 

 the work went on, two things happened. First, certain 

 and sure evidence was obtained that the outer atmosphere 

 extended much farther from the sun than had been pre- 

 viously supposed by those most competent to form a just 

 opinion ; and, further, while the extent of the atmosphere 

 was thus engaging attention, the chemical inquiry had 

 been carried so far that we thought we were justified in 

 saying, not only that the sun's atmosphere contained just 

 such substances as ours would do if our little earth were 

 suddenly turned into a mass of vapour, but that certain 

 substances occupied such and such positions in the 

 atmosphere, while others were to be sought for else- 

 where. 



Thus outside all, it was imagined, there was a substance 

 about which we know nothing here, because we cannot 

 find anything which produces the same spectrum. Inside 



