May 24, 1900] 



NATURE 



79 



tt thus appears that the recent more exact determinations 

 have raised what was probable when I wrote my memoir into 

 being now almost certain, by showing with greatly increased 

 clearness — 



(1) That argon is unable to escape from the earth. 



(2) That helium is slowly escaping, and presumably was in a 

 position to escape more freely in the distant past. 



It is interesting to observe that another moot question in 

 astronomy seems to be resolved by Prof. Ramsay's work. It is 

 known that the dynamical relation of the vapour of water to 

 Mars is nearly the same as that of helium to the earth. We 

 are accordingly now justified in presuming with greater confi- 

 dence that water cannot remain upon Mars, that accordingly 

 the polar snows of that planet are probably carbon dioxide, and 

 that some of the other appearances which have been observed are 

 due to the shifting of low-lying fogs of this vapour as they travel 

 alternately towards the two poles. 



G. Johnstone Stoney. 



8, Upper Hornsey Rise, N., May 20. 



" Plotosus canius" and the "Snake-stone." 



Possibly the following facts may possess interest for some of 

 your readers : — 



A good many years ago, when sea-bathing in the Old Straits 

 of Singapore {i.e. those separating the island from the Malay 

 Peninsula), I put my foot in a slight muddy hollow in the sandy 

 sea- bed ; the moment I did so, I received an agonising stab near 

 the ankle (from some red-hot poisoned blade, it seemed) which 

 drove me in hot haste ashore, where a Malay constable, on 

 hearing what had happened, and on examining the wound, pro- 

 nounced my assailant to be the " ikan sSmbilang" (sembilang 

 fish), Plotosus caitius, one of the siluroids, I am informed by 

 Mr. Boulenger of the British Museum. The fish is armed with 

 three powerful spines on the 'head, one projecting perpendicu- 

 larly from the top, and one projecting horizontally from each 

 side. 



The Malay lost no time in running to the barracks near by, 

 whence he shortly returned with a little round charcoal-like 

 stone about the size of a small marble. This he pressed on to 

 the wound, to which it adhered, and remained there by itself, 

 without any continuation of pressure, for a minute or more. 

 Then it fell oft', and black blood began to flow, which, after a 

 little, was succeeded by blood of normal colour. The pain, which 

 had been excessively acute, began to diminish soon after this, 

 and in an hour had practically disappeared. The wound gave 

 me no further trouble, but a fortnight afterwards I noticed a hole 

 about the size of a pea where the wound had been. 



Another gentleman, who, curiously enough, had suffered in 

 the same way in another part of Singapore the same day, was 

 not so fortunate in his cure, being completely laid up for six: 

 weeks. 



The black stone applied by the Malay to the wound came, 

 he alleged, from the head of a snake, and claimed, therefore, to 

 be a bezoar stone. It was, no doubt, a snake-stone, probably 

 made of charred bone, and therefore porous in character, which 

 would account for the adhesive and absorptive powers it displayed 

 in my case. 



In his " Thanatophidia of India," Sir J. Fayrer (quoted by 

 Yule in " Hobson-Jobson ") expresses entire disbelief in the 

 efficacy of these stones as remedies ' ' in the case of the real bite 

 of a deadly snake," owing to the extreme rapidity with which, 

 in such a case, the venom pervades the system. 



However this may be, the late Prof. Faraday, after exami- 

 nation of one of these stones, supplied by Sir Emerson Tennent 

 (quoted by Yule), credits it with certain absorbent powers, and it 

 would seem a pity that the undoubted value of such stones, at all 

 events in minor cases, where they may save a great deal of suffer- 

 ing, should be tdiscredited. 



Another remedy, considered of some value by Malays for the 

 stab of Plotosus canius is the sap of Henslowia Lobbiana, 

 which grows freely on the coasts of the Malay Peninsula. 



Among other marine offenders of this class dreaded by Malays 

 are several varieties of the skate or sting-ray, *' pari" as they 

 are generically called, and some of the " iSpu," of which the 

 only dangerous one, I have Mr. Boulenger's authority for saying, 

 is the " lepu " proper, viz. Synancia horrida. When the skate 

 reaches a large size, he will drag a fisherman's canoe a long 

 way. 



Among the Medusae, one much dreaded is known as "ampai," 



NO. 1595. VOL. 62] 



from its long fringes. The effects, unless a remedy can speedily 

 be found, are painful and trying to a degree, seeming to pene- 

 trate the whole frame, as it were, electrically, at once specially 

 affecting the seat of any ailment, and even the teeth and the 

 hair. I have never suffered from it myself, but am enabled 

 to speak to these points from two cases which came under 

 my personal observation. A valuable remedy for this sting, if 

 applied soon, is the juice of the young fruit of the papaw 

 {Carica papaya). 



A further illustration of the value of some native remedies is 

 supplied by a case which occurred some years ago at Malacca, 

 during my residence there, though I cannot state what the 

 remedies employed were. 



A young gentlemen in the office of the Telegraph Company 

 went out to bathe in the sea one night from the end of the pier 

 (in any case rather a rash proceeding, if only for the occasional 

 presence of crocodiles !), when he found himself in the embrace 

 of some creature with long tentacles, from which, after desperate 

 struggles, he eventually succeeded in freeing his legs and his 

 arms, and in regaining the pier. The Colonial surgeon could do 

 nothing for him, and he was in such tortures that for a time he 

 seemed to have lost his mental balance, but nine or ten days 

 after the occurrence a native practitioner, being called in, cured 

 him completely. D. Hervey. 



The Elms, Aldeburgh, May. 



Microphotography, Isophotography, 

 Megaphotography. 



I HAVE read with much interest your article on microphoto- 

 graphy (p. 4) at its best. Possibly some of your photographer 

 readers may be glad to know that microphotography of sorts is 

 within the reach of all who possess a microscope with suitable 

 substage-condenser and a camera. The results may not com- 

 pete with the best, but they are very useful. I find that any 

 transparent object which can be conveniently seen in the micro- 

 scope can be reproduced in the camera. If the fine adjust- 

 ment is good enough for ordinary work, it is good enough for 

 photographic work. 



One of my earliest attempts was to photograph fluid inclu- 

 sions in quartzes with ordinary sunlight, and rock-sections 

 polarised. The only difficulty was that the sun would not keep 

 still, and without a heliostat the work was most troublesome, 

 not to say aggravating. In one case, a mere movement of the 

 condenser-diaphragm made the bubble in the inclusion fly back- 

 wards and forwards. A negative was taken in each position, 

 and a lantern slide taken of each negative. With a Uttle device 

 in the double lantern the motion of bubbles in inclusions can 

 be shown on a nine- foot screen. These negatives were taken with 

 a l/i6th immersion, the camera being extended with a brown 

 paper tube, and the extra apparatus did not cost one shilling. 



Up to a ^-inch objective, ordinary gas, with isochromatic 

 plates, does very useful work. The only difficulty to surmount 

 is to handle the focusing apparatus, and see the focusing 

 screen at the same time. A hand mirror solves the problem. 

 But a fine adjustment is really scarcely necessary, as it is easy 

 to focus with the camera as in ordinary photography. 



It is o'"ten desirable to photograph objects their exact size. 

 Before the Kent's Cavern Collection was divided, I photo- 

 graphed the choicest examples for the Torquay Natural History 

 Society. The implements were fixed with beeswax on a piece 

 of plate-glass, which could be placed in any position and backed 

 by any desired background. I sent a couple of prints to the 

 International Amateur Photographic Exhibition at Vienna, and 

 the jury, much to my surprise, awarded them a diploma. The 

 extra apparatus certainly did not cost lOi-., and the negatives 

 were taken in the lecture-room of the Natural History Society 

 under some disadvantages. 



Of megaphotography I have but a single experience. While 

 observing the transit of Venus, I thought I would try a photo- 

 graph. I drilled a hole in the telescope cap for diaphragm ; 

 took off the eye-piece and stuffed the telescope into a common 

 camera, with a red cloth to make it light-light ; exposed six 

 negatives with hand exposure on instantaneous plates. Result : 

 four passable negatives and one good one. This quite unlooked- 

 for success was due to some back volumes of Nature which 

 propped up the camera. The success was really a downright 

 '* fluke" ; for, knowing the exposure must be hundreds of times 

 too much, I added a quantity of bromide of potassium to the 



