an autobiography-第79节
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？ floating in a fluid of their own； or very nearly their own； specific gravity？ Some kind of solidity or coherence they must have； or they would not retain their shape in the violent movements of the atmosphere which the change of the spots indicate。
〃I observe that in the bridges all their axes have an approximate parallelism； and that in the penumbra they are dispersed； radiating from the inside and the outside of the spot； giving rise to that striated appearance which is familiar to all observers of the spots。
〃I am very glad that you have pitched your tent in this part of the world； and I only wish it were a little nearer。 You will anyhow have the advantage at Penshurst of a much clearer atmosphere than in the north； but here； nearer the coast； I think we are still better off。 〃Mr。 Maclaren holds out the prospect of our meeting you at Pachley at no distant period； and I hope you will find your way ere long to Collingwood。 I have no instruments or astronomical apparatus to show you； but a remarkably pretty country； which is beginning to put on （rather late） its gala dress of spring？'
Sir John afterwards requested my permission to insert in his Outlines of Astronomy； of which a new edition was about to appear； a representation of 〃the willow…leaved structure of the Sun's surface；〃 which had been published in the Manchester transactions；to which I gladly gave my assent。 Sir John thus expresses himself on the subject： 〃The curious appearance of the 'pores' of the Sun's surface has lately received a most singular and unexpected interpretation from the remarkable discovery of Mr。 J。 Nasmyth； who； from a series of observations made with a reflecting telescope of his own construction under very high magnifying powers； and under exceptional circumstances of tranquillity and definition； has come to the conclusion that these pores are the polygonal interstices between certain luminous objects of an exceedingly definite shape and general uniformity of size； whose form （at least as seen in projection in the central portions of the disc） is that of the oblong leaves of a willow tree。 These cover the whole disc of the Sun （except in the space occupied by spots） in countless millions； and lie crossing each other in every imaginable direction。。。。 This most astonishing revelation has been confirmed to a certain considerable extent； and with some modifications as to the form of the objects； their exact uniformity of size and resemblance of figure； by Messrs。 De la Rue； Pritchard and Stone in England； and M。 Secchi in Rome。〃
On the 25th of February 1864； I received a communication from Mr。 E。 J。 Stone； first assistant at the Royal Observatory； Greenwich。
The Astronomer…Royal； he said； 〃has placed in my hands your letter of February 20。 Your discovery of the 'willow leaves' on the Solar photosphere having been brought forward at one of the late meetings of the Royal Astronomical Society； my attention was attracted to the subject。 At my request； the Astronomer…Royal ordered of Mr。 J。 Simms a reflecting eye…piece for our great equatorial。 The eye…piece was completed about the end of January last； and at the first good opportunity I turned the telescope on the Sun。
〃I may state that my impression was； and it appears to have been the impression of several of the assistants here； that the willow leaves stand out dark against the luminous photosphere。 On looking at the Sun； I was at once struck with the apparent resolvability of its mottled appearance。 The whole disc of the Sun； so far as I examined it； appeared to be covered over with relatively bright rice…like particles； and the mottled appearance seemed to be produced by the interlacing of these particles。
〃I could not observe any particular arrangement of the particles； but they appeared to be more numerous in some parts than in others。 I have used the word 'rice…like' merely to convey a rough impression of their form。 I have seen them on two occasions since； but not so well as on the first day； when the definition was exceedingly good。
〃on the first day that I saw them I called Mr Dunkin's attention to them。 He appears to have seen them。 He says； however； that he should not have noticed them if his attention had not been called to them。〃
The Astronomer Royal； in his report to the Admiralty on my discovery； said：
〃an examination of the Sun's surface with the South…East Equatorial； under favourable circumstances； has convinced me of the accuracy of the description； which compares it with interlacing willow leaves or rice grains。〃
In March 1864 I received a letter from my friend De la Rue； dated from his observatory at Cranford； Middlesex； in which he said： 〃I like good honest doubting。 Before I had seen with my own eyes your willow leaves； I doubted their real existence； but I did not doubt your having seen what you had drawn。 But when I actually saw them for the first time； I could not restrain the exclamation； ' Why； here are Nasmyth's willow leaves！ ' It requires a very fine state of the atmosphere to permit of their being seen； as I have seen them on three or four occasions； when their substantial reality can no longer be doubted。〃* ＇footnote。。。 Let me give another letter from my friend； dated the Observatory； Cranford； Middlesex； October 26； 1864。 He said：… 〃I am quite pleased to learn that you like the large photograph。 The first given to my friend was destined for and sent to you。 No one has so great a claim on the fruit of my labours； for you inoculated me with the love of star…gazing； and gave me invaluable aid and advice in figuring specula。 I daresay you may remember the first occasion on which I saw a reflecting telescope； which was then being tried on the sun in a pattern loft at Patricroft。 You may also recall the volumes you wrote in answer to my troublesome questions。 Yours very sincerely WARREN DE LA RUE。〃 。。。＇
Sir John Herschel confirmed this information in a letter which I received from him in the following May。 He said 〃that Mr。 De la Rue and a foreign gentleman； Hugo Muller； had been very successful in seeing and delineating the 'willow leaves' They are represented by Mr。 M。 as packed together on the edge of a spot； and appear rather like a bunch of bristles or thorns。 In other respects the individual forms agree very well with your delineations。〃 Another observer had discovered a marvellous resemblance between the solar spots and the hollows left by the breaking and subsidence of bubbles； which rise when oil varnish； which has moisture in it； is boiled； and the streaky channels are left by the retiring liquid。 〃I cannot help；〃 adds Sir John； 〃fancying a bare possibility of some upward outbreak； followed by a retreat of some gaseous matter； or some dilated portion of the general atmosphere struggling upwards； and at the same time expanding outwards。 I can conceive of an up…surge of some highly compressed matter； which relieved of pressure； will dilate laterally and upwards to an enormous extent （as Poullett Scrope supposes of his lavas full of compressed gases and steam）； producing the spots； and； in that case； the furrows might equally well arise in the origination as in the closing in of a spot。〃
I had the honour and happiness of receiving a visit from Sir John Herschel at my house at Hammerfield in the summer of 1864。 He was accompanied by his daughter。 They spent several days with us。 The weather was most enjoyable。 I had much conversation with Sir John as to the Sun spots and willow…leaf…shaped objects on the Sun's surface； as well as about my drawings of the Moon。 I exhibited to him my apparatus for obtaining sound castings of specula for reflecting telescopes。 I compounded the alloy； melted it； and cast a 10…inch speculum on my peculiar common…sense system。 I introduced the molten alloy； chilled it in a metal mould； by which every chance of flaws and imperfections is obviated。 I also showed him the action and results of my machine； by which I obtained the most exquisite polish and figure for the speculum。 Sir John was in the highest degree cognisant of the importance of these details； as contributing to the final excellent result。 It was therefore with great pleasure that I could exhibit these practical details before so competent a judge。
We had a great set…to one day in blowing iridescent soap bubbles from a mixture of soap and glycerine。 Some of the bubbles were of about fifteen inches diameter。 By carefully covering them with a bell glass； we kept them for about thirty…six hours； while they went through their changes of brilliant colour； ending in deep blue。 I contrived this method of preserving them by placing a dish of water below； within the covering bell glass； by means of which the dampness of the air prevented evaporation of the bubble。 This dodge of mine vastly delighted Sir John； as it allowed him to watch the exquisite series of iridescent tints at his tranquil leisure。
＇Image＇ From a photograph of the Moon； exhibiting the bright radial lines。
＇Image＇ Glass globe cracked by internal pressure； in illustration of the cause of the bright radial lines seen on the moon。
I had also the pleasure of showing him my experiment of cracking a glass globe filled with wat
