Aug. 24, 1876] 



NATURE 



35i 



lower eyelid produce this effect, whilst it is evident that a prism 

 of the shape taken by the liquid in the angle must produce it. 



2. If the bright point be examined in front of a looking-glass, 

 so that the eye, its reflection, and the point are in a straight line, 

 it will be found that (b) does not begin to be visible till the eye- 

 lid is just beginning to eclipse the pupil, showing that it is the 

 light which grazes the lid that produces the effect. I have accu- 

 rately reproduced the phenomenon by fitting a lens of short focus 



Fig.^ 



£iff.4 



into a pair of artificial eyelids, moistening the angle between the 

 lens and lid, and photographing a bright point with the combina- 

 tion thus made. The diffraction effect (c) was also reproduced in 

 this manner when the lids were brought close together. 



The phenomenon (a) may be studied in the following 

 manner :— Throw into the eye, by means of a lens or mirror, a 

 pencil of light so widely divergent as to form a luminous patch 

 on the retina, whose border is the shadow of the iris. If the pencil 



£rg.e 



proceed from a point, this border is well defined and dust on the 

 cornea and any small irregularities in the distribution of moisture 

 on its surface are rendered clearly visible by the diffraction rings 

 and bands which surround their shadows. But what is most 

 striking is the star-shaped figure (Fig. 6) 

 which occupies the whole lighted area. 

 If now the divergence of the pencil 

 be gradually diminished, which it may 

 be by withdrawing the eye further from 

 the focus of the lens, this area dimi- 

 nishes in size and increases in bright- 

 ness towards the ctntre, leaving, how- 

 ever, the rays of the star still bright, 

 and protruding into the region which has 

 now become unilluminated ; and when 

 the luminous point is far enough off to 

 enable the eye to focus rays proceeding 

 from it, the phenomenon (a) is seen to 

 be the limiting form of this star-shaped figure. The rays in the 

 figure correspond wiih the stellate structure of the crystalline 

 lens, to which, therefore, I conclude that (a) is due. 



Arnulph Mallock 



Antedated Books 



As Editor of the Zoological Society's Transactions, I must 

 maintain, in direct opposition to " Another F.Z.S.," that we set 

 a good, and not a bad, example in dating our books. The parts 

 of the Transactions not being issued at regular dates, I haye 



adopted the plan of placing the date at which the paper is going 

 finally through the press at the foot of each sheet, for the very 

 purpose of giving its correct date as nearly as possible. The 

 part is always on sale within a month at least, I think I may say, 

 after this date ; so that this date and that of publication are to 

 all practical purposes identical. P. L. Sclater, 



Secretary to the Zoological 

 Aug. 22 Society of London 



Mr. R. Bowdler Sharpe makes a singular defence to my 

 comments on his " evil practice " of issuing, in August, 1876, a 

 work dated on the cover May, 1875. He says that if I had 

 looked into the interior I should have found "abundant evi- 

 dence " to convince me that the date on the cover was a false 

 one. Seeing that when I wrote.my former letter I had only just 

 received the number from the publishers, I had no need to 

 search for further evidence of such being the fact. Mr. Sharpe 

 must be aware that the covers of works issued in parts are often 

 bound up for the express purpose of preserving a record of the 

 date of issue. How will this plan operate in the case of the 

 second edition of the " Birds of Africa ? " 



"Another F.Z.S." states that in his copy the date "May, 

 1875 " has a line drawn through it. This is not the case with 

 my copy, nor is it so in others which I have examined. 



F.Z.S. 



Kerguelen's Land 

 If Mr. R. Bovv^dler Sharpe considers that, having published a 

 description of the new Teal from Kerguelen's Land, he has done 

 all that is necessary in relation to the collection of birds made by 

 Mr. Eaton in that distant island, he will, I fear, find but i^^ 

 persons to agree with him. Most of his brother naturalists will 

 side with me that our American friends have shown much greater 

 energy in getting out a complete account of the ornithology of 

 this interesting island at an early date than Mr. Sharpe in issuing 

 a short notice of the single undescribed species. 



The Reviewer of "The Birds of 

 Kerguelen's Land " 



A Large Meteor 



I have just seen a large meteor. It fell vertically in a line 

 passing half-way between the pole-star and the nearer pointer, 

 disappearing about 15° above the horizon. Where it came from 

 I did not see. At disappearance it seemed a very elongated pear- 

 shape, and changed colour from red to violet (commencing at 

 the edges). Its horizontal diameter was about 20'. Time 8. 10 

 P. M. about ; my point of view, 4 miles due south of the dome 

 of St. Paul's. 



I may add, that on the night of Thursday, loth, between half- 

 past 11 and I, while on a long drive in the neighbourhood of York, 

 and looking up at the clear sky only as circumstances permitted, I 

 counted twenty, and saw more, the moon shining brightly at the 

 time. Richard Verdon 



London, Aug. 21 



[Mr. Paul Robin, writing from Sheerness, states that on Mon- 

 day evening, at 8.10 P.M., he saw a meteor brighter than Jupiter, 

 with a white luminous train of about 5 deg. Its course crossed a 

 line from the pole-star, joining the pointers.] 



THE ''CHALLENGER'' EXPEDITION 



WE have already published (vol. xiv. p. 197) the weighty 

 testimony borne to the value of the Challenger 

 Expedition by the leaders of science in Vienna. The 

 following no less valuable address to Sir C. Wyville 

 Thomson has been sent us for publication : — 



To Prof. Sir C. Wyville Thomson, F.R.S., Director of the Civilian 

 Staff of the " Challenger" Expedition, Ediitburgh. 



R. Museo di Fisica e Storia Naturale di Firenze, 

 Florence, July 7, 1876 

 Sir, — The professors of the Natural Science Section of the 

 Royal Institute of Florence have followed with the most intense 

 interest the researches on the deep-sea fauna initiated by you 

 during the Lightning and Porcupine expeditions, and so splen- 

 didly followed up during the voyage round the world of the 

 Challenger. With anxious expectation we have followed the 



