634 



NA TURE 



[Oct. 30, 1884 



The suggestion of Prof. E. Douglas Archibald (October*), p. 560) 

 that the dimensions of the great corona prove it to be caused by 

 hexagonal prisms, as is the ordinary solar halo, is surely not 

 tenable when its entirely different appearance and colour are 

 considered ; and it must arise from a different cause as hinted 

 by Prof. Le Conte (vol. xxix. p. 403). The solar halo is a 

 narrow ring brightest at a distance of about 23 from the sun ; 

 whereas this corona is brightest close to the sun, fading con- 

 tinuously, and at first rapidly, as the distance from the sun in- 

 creases. It varies somewhat in colour, depending on the sun's 

 altitude and other causes, but is always greenish or bluish near 

 the sun, and at an estimated distance of T to IO therefrom, 

 rather abruptly changes to reddish or brownish. This colour is 

 nearly the same for a great distance, though inclining to orange 

 towards the sun, and to pink in its outer part. When seen 

 under favourable circumstances [e.g. in Visp-thal) I have traced 

 it faintly to a distance of fully 75°. The solar halo, on the other 

 hand, is usually dull orange on the edge next the sun, and bluish 

 towards the outside ; and when its colours are very distinct, all the 

 prismatic colours are visible, the red always being next the sun : 

 so that the colours are in reverse order in the two phenomena, so 

 far as they occur. Whether there is any ice concerned in the 

 production of the corona or not, it cannot be in the form of 

 hexagonal crystals, for there is no trace of the ordinary halo in 

 connection with the corona ; and whenever the two phenomena 

 are visible together, the halo is always on true clouds. 



Sunderland, October 27 T. W. Backhouse 



After-Glow 



The after-glow here on Sunday night, the 26th, at 6.45 p.m., 

 was wonderfully grand, intensely bright golden colour extending 

 from horizon to about 45°, and graduated into delicate rose, 

 again graduating to pale ashy gray. Indeed at no period since 

 first observing these after-glows (now over one year) have I seen 

 one brighter. Robert D. Gibney 



Falmouth, October 28 



The Distribution of Scientific Works Published by the 

 British Government 

 Recently I have enjoyed an opportunity of visiting a number 



of the scientific institutions of America, but it was with a feeling 

 of humiliation that I learnt that several of the best-known and 

 most important of them have to pay for works like the various 

 Survey and Challenger Reports which are published by the 

 British Government. It would have been possible perhaps to 

 have obtained some statistics on the subject, but I must confess 

 to having been restrained by a feeling of shame from making 

 direct inquiries ; what I did hear about it merely reached me in 

 the course of casual conversation. 



There are few of your readers probably who do not know of 

 the extraordinary liberality of the American Government with 

 reference to their publications, and when speaking of it to Major 

 Powell, Director of the United States Geological Surveys, I was 

 told by him that in his department it was considered that the 

 cause of education, the spread of know ledge, and their own im- 

 mediate objects were most effectually aided by a widespread dis- 

 tribution of their publications. 



We owe much of this liberality, no doubt, to the forethought 

 and generosity of our own countryman Smithson, the principal 

 function of the Institution founded by him being to arrange for 

 the exchange and despatch of books and specimens. 



There are perhaps few directions in which the cause of science 

 would be more directly benefited just now than by the establish 

 ment of an institution in England which would undertake the 

 management of the exchanges of the scientific Societies of the 

 United Kingdom. I am aware that there are paid agencies for 

 the purpose, but what is wanted is a free agency which would 

 undertake the duty for the large Societies and relieve those that 

 are struggling from charges which now pros heavily on their 

 resources. 



The great desideratum, however, is a man like Smithson, 

 who, possessing wealth, would be willing to give or bequeath it 

 for the purpose of founding such an institution. Here is an 

 opportunity for any person of capital desirous of doing good and 

 preserving his name to all posterity by one and the same act. 



To return, however, to the main object of this letter, cannot 

 anything be done to increase the "free list" of Government 

 publications? Surely there must be stored away vast quantities 

 of Survey and other serial publications which, if they were 



handed over to the Smithsonian Institute, would, I feel certain, 

 be gratefully accepted and judiciously distributed among the- 

 libraries of America. V. Ball 



Science and Art Museum, Dublin, October 25 



Insect Pests in Ceylon 



Amongst the "Notes" in your last issue, p. 615, is an 

 extract from a Ceylon paper of a report by Dr. Trimen as to an 

 insect " which has caused much alarm by its depredations on 

 cacao and cinchona plantations," and that Dr. Trimen thinks 

 " the only serious damage to cacao comes from the Helopeltis 

 antonii, which appears to be a recent importation to Ceylon, 

 although well known in Java." 



Quite recently I received from my friend Mr. R. McLachlan 

 some fragments of several specimens of a Hemipteron which he 

 had received from Ceylon, identified as Helopeltis antonii, and 

 said to be causing damage to the planters' crops, and my corre- 

 spondent, having doubts as to the proper identification, had for- 

 warded the specimens (!) for my examination. 



Before stating that an error of identification had been made,, 

 it is necessary to say what Hehpeltis antonii really is. That 

 species described by Dr. Signoret is a member of the Capsidae, 

 possesses nodulose or incrassated femora, and of course, like 

 other members of that family, may be considered as injurious to 

 some kind of vegetation. The specimens I received (sans head 

 and pronotum) had also nodulose or incrassated femora, and 

 though somewhat similar also in colour to the Helopeltis antonii, 

 clearly belonged to the family Reduviidae, whose habits and 

 food are of a totally dissimilar character. It is therefore possible 

 that both species occur in Ceylon ; the one is being frequently 

 mistaken for the other, a matter of some moment to the planter, 

 as in destroying the Reduviid he may be at the same time killing 

 the worst enemy of the real pest. W. L. Distant 



Russell Hill Road, Purley, Surrey 



The Pentacrinoid Stage of Antedon rosaceus 

 I WAS somewhat surprised at finding this summer, in Lamlash 

 Bay, on the east coast of Arran, Antedon rosaceus in the penta- 

 crinoid stage readily obtainable up to the end of September, 

 and would be glad to hear from others who have been observing 

 Antedon, their experience of the duration of the stalked con- 

 dition. It is well known that the adult Antedon ro'aceus is 

 abundant at Lamlash, and that young specimens in the penta- 

 crinoid stage are common on Laminaria in the earlier part of 

 the summer; but I have always found the " pentacrinoids " 

 rare or absent during August, and I have certainly never before 

 found one in September. I find that the late Sir Wyville 

 Thomson states, in his memoir " On the Embryogeny of Antedon 

 rosaceus" (Phil. Trans. 1865, p. 513), that the ova are mature 

 towards the end of May or beginning of June, and that, although 

 the time spent in the larval stages may be to a certain extent 

 shortened or prolonged by surrounding conditions, the dis- 

 engagement of Antedon rosaceus from its stalk " constantly occurs 

 between the middle of August and the middle of September" 

 (p. 517). From this one would not expect to find any specimens 

 in the pentacrinoid stage after the middle of September. This 

 season, however, while dredging chiefly in the southern part of 

 the bay near King's Cross Point, I obtained young stalked 

 Antedons nearly every day, between September 15 and 25. I 

 generally got one, two, or three specimens in a forenoon's 

 dredging (usually four or five hauls of the dredge). On Sep- 

 tember 27, the last clay I dredged, I found, on some Fuens 

 brought up from six or seven fathoms at the south entrance to 

 the bay. upwards of twenty specimens of "pentacrinoids." They 

 were of all sizes, from 3 mm. up to J cm. in length of stalk. 

 The last were evidently just ready to be set free, and in fact 

 several of them became disengaged from their stalks while I 

 was watching them in a glass dish during the afternoon. The 

 smaller specimens obtained that day were, from their structure, 

 evidently very much younger, and could not have become free 

 for a considerable time : how long I do not know, and would 

 be glad to learn. Probably they would still hive been in the 

 pentacrinoid condition had they lived. W. A. Herdman 



University College, Liverpool, October 21 



Curious Phenomenon 

 A very curious phenomenon has just come under my notice, 

 which is, I think, not unworthy of being put on record. I have 



