September 29, 1898] 



NATURE 



521 



resembling one of those local fogs which every one has seen, and 

 which may give to a valley or even a slight depression the 

 appearance of being snowed up. It occurs when the sea is 

 colder than the atmosphere, and the latter still and heavily 

 loaded with aqueous vapour. Under these circumstances, a 

 layer of air immediately in contact with the water is chilled 

 below the dew point and becomes misty, while that above 

 remains transparent : the upper surface of such a fog, which 

 is only a few inches thick, being seen by the reflected light of 

 the sky" {"An Engineer's Holiday," vol. ii. p. 314). 



The temperature of the sea on the night in question was 

 70° F., while that of the air was 79°, an unusual amount of 

 difiference in the Arabian sea. Water, brought on deck by a 

 bucket, showed no signs of milkiness, though crowded as usual 

 with various phosphorescent organisms. Dan. PiDGEON. 



The Long House, Letherhead, September 24. 



Luminous Clouds .' 



I OBSERVED a phenomenon at the Lizard, on the night of 

 September 10, which is new to me, but what I presume is meant 

 by luminous clouds. 



At 10.48 p.m. several others and myself saw a large patch of 

 what looked like luminous mist suddenly appear just to the 

 south of the constellation Perseus. It only lasted a very short 

 time, but quickly reappeared accompanied by another which 

 extended from near the extremity of the first to the higher part 

 of Cassiopeia. The longer axes of these patches were in one 

 line nearly east and west, and low down in the west in this line 

 produced, appeared and reappeared a similar patch. Shortly 

 afterwards a similar patch appeared with its longer axis on the 

 same line almost at the zenith. The line of direction of these 

 clouds formed a small angle with the Milky Way. I may state 

 that the sky was quite clear except for a bank low down in the 

 north, and that the light of these clouds was sufficient to attract 

 attention although one was not looking in their direction, and 

 although they were so high in the sky. Several fugitive patches 

 appeared in the west at short intervals, and at o. 10 a.m. (nth) 

 a very bright patch was to be seen in the north-east. Just after- 

 wards the patch in the west reappeared, and with one or two 

 short interruption." and, at first, considerable variation of 

 intensity, remained i. itil close on i a.m. The position remained, 

 as far as I could see, constant, and at about 0.30 a.m. I fixed its 

 position by means of a flag-staff and the top of a wall, and on 

 the following day I took the bearings by the theodolite. The 

 lower edge of the cloud was nearly straight and horizontal, and 

 tlie angles are for the centre of this lower edge. They are as 

 follows : N. 281° 12' E. (mag.), elevation 7° 18'. 



I thought that if any one is collecting information on the 

 subject, a report from the extreme south and west might be 

 useful, especially as I was able to get the bearing pretty 

 accurately. 



I may add that the aurora of the evening of the 9th was well 

 observed throughout Cornwall, though I do not know that I can 

 give much information that would be of value with respect to it. 



Arthur P. Jenkin. 



Trewirgie, Redruth, September 13. 



"Crannoges" in Estuaries. 



I FIND in Nature of September 15 a notice of certain 

 remains near Dumbarton as the only known specimens of 

 "crannoges" in tidal water. 



The farm-house of Cranny, in the townland of the same 

 name, parish of Inver, County Donegal, Ireland, is supposed to 

 stand on an artificial island in a tidal estuary, that of the Eany, 

 or Eidhneach (meaning Ivy) Paver. The mound is now sur- 

 rounded by a masonry revetment. 



Opposite it, on the right bank of the same estuary, is a low 

 mound which seems artificial, and lower down the old church 

 of St. Natalis stands on another. 



I have nothing to propound, but the ground may be worth 

 examining. I have known it for many years, and think all 

 three " crannoges." There is some printed record, not now 

 before me, of the discovery of wooden framework on the right 

 bank of the Eany, in glebe land. W. F. Sinclair. 



Chelsea, September 16. 



Transference of Heat in Cooled Metal. 



Lorsque je vous ai ecrit le 30 Juin dernier pour vous prier 

 dappeler, dans votre estimable journal, I'attention sur un 

 phenomene de conduction de chakur dans une barre ; je pensais 

 parler d'un phenomene bien connu ainsi que je le disais dans 

 ma lettre. Je desirais simplement provoquer de la part de 

 quelc^ues uns de vos lecteurs, soit des recherches, soit des 

 enquetes analogues a celle que j'avais fait de mon cote aupres 

 des artisans et ouvriers ; mais je n'avais nullement la pretention 

 de signaler un phenomene notiveau. Le premier physicien qui 

 en ait parle est a ma connaissance M. Izarn, professeur de 

 physique au lycee de Clermont-Ferrand (France), et qui est 

 connu par bien d'autres travaux. Voyant qu'on a I'air de 

 m'attribuer la decouverte de ce phenomene, je vous serais tres 

 reconnaissant si vous vouliez bien detromper les lecteurs de votre 

 journal et remettre les choses au point. Henry Bourget, 



Oljservatoire de Toulouse, Septembre 13. 



Horn-feeding Larvae. 



Reading the correspondence in Nature on larvae in ante- 

 lope horns, reminded me of an experience in India. I was 

 on a shooting trip near the Niti Pass in May, and bought a 

 .sheep for food from a native. Within five minutes of it 

 being killed its horns were removed from the head, and it was 

 found that they contained each some dozen maggots, white, and 

 about half an inch in length. The horns had not been per- 

 ceptibly perforated, and seemed quite sound. This fact may be 

 well known, but I give it for what it is worth. 



G. G. Traherne. 



" Purple Patches." 



In Nature of November 12, 1896, there appeared a letter 

 asking for some explanation of certain purple patches frequently 

 noticed by the writer (A. Pedder) on roadways and pavements, 

 especially at Bath. There were but three replies, two of which 

 suggested "copying-ink" pencils as responsible. 



The following notes, made recently in Derbyshire by myself, 

 seem so nearly to fit the case that I venture to think a cause 

 such as here described, or one closely allied, might explain some 

 at any rate, of the cases mentioned. Here are the verbatim 

 notes : — 



"29/8/98 — At Axe Edge last Wedne.sday I noticed on a 

 coal-pit ventilating shaft (Thatch Marsh Colliery) on the moor 

 certain deepish blue masses on a ledge near the base. Some 

 masses brighter blue, others nearly black. Under a lens 

 appeared to contain horny parts of larvre and many small seeds. 

 They are probably the droppings of birds. They leave a bluish 

 stain on the stone. 



" To-day I noticed the same on some pieces of stone on the 

 road to Goyt's Bridge, a steep, rocky road. 



" 30/8/98.— Visited Axe Edge shaft again. There were no 

 fresh deposits on it. This may be due to almost continuous 

 rain the last four days ; but the stains are still there. Also 

 found deposit on one or two stones round shaft and on a piece 

 of wooden staging. They were very plentiful, especially on the 

 tops of the six posts of this staging, where one would expect 

 birds to settle chiefly. The colour and stains were just the 

 same — some reddish purple and some bluish purple. The 

 colour is thus evidently due only to the excreta (?), and not to 

 the body on which deposited. The seeds appear reddish, and 

 it seems likely that the colour is due to them. (Bilberries are 

 plentiful on the surrounding moor)." 



" 1/9/98. — The seeds are identical with bilberry, and on 

 extracting the excreta with cold water a claret-red colour is 

 obtained, which leaves a greenish-blue stain on paper." 



Dulwich. F. Southerden. 



Re-Blossoming of Horse-Chestnut. 



There is at present (September 20) a tree in South-End, 

 Hampstead, showing a bunch of fresh green leaves and a well- 

 formed spike of flowers. Some years back (1893, I think), 

 another tree, in the same plantation, put forth leaves and 

 blossom in September. J. J. W. 



NO. 1509, VOL. 58] 



