Oct. 1 6, 1884] 



NA TURE 



59i 



In the late eclipse, as viewed from this station (where 

 the sky was not only perfectly cloudless, but free from the 

 least suspicion of haze), the obscuration of the moon was 

 carried to a degree far beyond anything witnessed in the 

 eclipses of recent times. For some time before and after 

 the middle of the eclipse (that is, about 10 p.m.) the only 

 trace of our satellite that remained in the sky was a faint 

 dingy-brown nebulous spot, to which it was impossible to 

 assign any definite form or dimensions, but which certainly 

 did not approach the moon in point of apparent size. So 

 inconspicuous was it that it was quite invisible through 

 the window of a room in which lights were burning ; and 

 in the open air, if one had not known exactly where to 

 look for it, one might have searched for some little time 

 without discovering it. I speak of course of the naked- 

 eye appearances. With an opera-glass the nebulous spot 

 was resolved into a well-defined disk of the proper dimen- 

 sions, but still very faint and dingy, the hue being a kind 

 of reddish-brown. It was further remarked that the illu- 

 mination was uniformly distributed over the disk, at least 

 so far as this, that there w-as no preponderance of light in 

 the direction of any one part of the moon's edge. This 

 is what should naturally have followed from the central 

 character of the eclipse, but it seems desirable to note 

 the circumstance with reference to a theory presently to 

 be mentioned. 



The most obvious explanation of the unusual obscurity 

 of the moon would be its unusually deep immersion in 

 the earth's shadow, but this view seems to be clearly dis- 

 proved by a comparison with the phenomena observed in 

 a former eclipse. Referring to a note which I made at 

 the time of the eclipse of August 23, 1S77, I find the fol- 

 lowing remark : — " The moon, even in the middle of the 

 total phase, was a conspicuous object in the sky, and the 

 ruddy colour was well marked. In the very middle of 

 the eclipse the degree of illumination was as nearly as 

 possible equal all round the edge of the moon, the central 

 parts being darker than those near the edge." Now the 

 duration of totality in that eclipse was ih. 44m. In the 

 late eclipse it was ih. 32m. The immersion of the moon 

 in the earth's shadow must therefore, I presume, have 

 been at least as deep on the former occasion as on the 

 recent one. It may be mentioned as an additional 

 argument against this explanation that in the late eclipse 

 the visibility of the eclipsed portion was observed to be 

 much less than usual even before the eclipse was com- 

 plete. In fact it was not until within a few- minutes of 

 the total phase that the eclipsed portion could be certainly 

 distinguished with the naked eye. 



Another obvious suggestion in the way of explanation 

 has reference to variations in the condition of that portion 

 of the earth's atmosphere through which the sun's rays 

 would pass to reach the moon. This explanation is not 

 without interest in connection with the remarkable sunset 

 effects of last winter, and, in a less degree, of the present 

 autumn. But there are serious difficulties in the way of 

 accepting it, for, in order to account for the observed 

 phenomena, it would be necessary to suppose that an 

 entire ring of the earth's atmosphere was uniformly 

 affected. A want of uniformity in this respect would not 

 cause merely an uneven illumination of the moon's disk, 

 which some observers seem to have noted, and which may 

 very well be set down to the actual differences on the 

 surface of the moon ; the effect would be specially 

 marked upon some part of the moon's edge, and would 

 be similar to what is observed soon after totality has 

 commenced and shortly before it ends. Nothing ap- 

 proaching to this appearance was to be seen in the 

 late eclipse at the time when the obscuration was 

 greatest. 



Is it possible that the surface of the moon may be in 

 some small degree self-luminous, and that a variation 

 (from unknown causes) in the degree of this self-h :min- 

 osity may account for the difference observed in the 



visibility of the moon in two eclipses, in both of which 

 the solar light was equally at its minimum ? 



Clifton, October 7 George F. Burder 



On the occasion of the total eclipse of the moon on 

 Saturday, October 4, the Director of the Pulkowa Ob- 

 servatory, near St. Petersburg, issued a circular to a 

 number of other observatories suggesting the use of the 

 opportunity to fix the exact diameter of the moon, the 

 mean value of the true diameter not being known to a 

 second. Even as regards a probably existing depression 

 of the surface of the moon, we know only that it cannot 

 be very great. The circular also requested observers to 

 watch attentively all stars, even those of the tenth magni- 

 tude, eclipsed by the moon, and their egress on the other 

 side, which is only possible during a total eclipse. In 

 order to make these observations exact, Prof. Dollen, of the 

 Pulkowa Observatory, calculated the number of such 

 stars covered by the moon on that date, which he finds 

 were 116, most of which are of the ninth and tenth mag- 

 nitude and only one of the sixth. He has, moreover, for 

 the use of observers, calculated the exact position of 

 these during the eclipse for no less than sixty observatories 

 from Pulkowa to the Cape, which is expected to give the 

 desired result. 



NOTES 



Our readers will hear with sincere regret that Prof. Huxley, 

 under the orders of his medical advisers, left England yesterday 

 for some months of absolute rest. When it is remembered how 

 many functions Prof. Huxley has to fulfil, we need hardly say 

 that the cause of his enforced retirement for a time is overwork. 

 His presence in England will certainly be missed during the 

 coming winter, and he may feel assured that he carries with 

 him the sympathies of many friends, known and unknown. 

 Prof. Huxley goes in the first instance to Venice. 



We heartily support the suggestion which has been made in 

 the Gardeners Chronicle that it would be most appropriate that 

 some memorial of the late Mr. Bentham should, subject to the 

 consent of the authorities, be placed in the Royal Herbarium at 

 Kew, to which he was such a benefactor, and in connection with 

 which his life-work was for very many years carried on. Official 

 etiquette would probably preclude any steps being taken by the 

 authorities at Kew in the matter ; and, indeed, it is a subject 

 that would more gracefully and appropriately be dealt with by 

 outsiders. 



Sir William Harcourt is always happy when he touches 

 on science, either to point a political shaft, or, as on Tuesday at 

 Derby, when descanting directly on its progress and bearings. He 

 showed himself well versed— as one bearing the honoured name of 

 Harcourt ought to be— in the 'history of scientific progress, and 

 in the high importance of science apart from its utilitarian uses. 

 Scientific study, in his conception, is above all others " the most 

 useful and the most ennobling." " Depend upon it," he concluded, 

 " if I may turn for a moment to the utilitarian view, these are 

 not days in which we, as a people, can afford to be idle or to be 

 ignorant. There i^ an immense competition going on in the 

 world in all departments of trade. Remember you have the 

 competition of countries where education of this character is of 

 a more complete character, far more complete than anything we 

 have in this country. If you go into Germany you will find in 

 every small town that there are institutions where the severest 

 education is given in all departments of technical knowledge. 

 The old days when people could afford to go on in an easy, 

 happy-go-lucky sort of manner are gone by. You may depend 

 upon it, in the race which we have to run in the world, a train- 

 ing of the severest description is requisite, so that we may hold 

 our own." We trust Sir William will bear his admirable Derby 



