i66 



NATURE 



S^Jtine 23, 1 88 1 



working out the explanation inductively. In the autumn of 1847 

 1 was spending a 1 evening with Dr. P. M. Roget, at his house 

 in Woburn Square, when among other subjects we conversed 

 upon was that of optical illusions. The inverted pin was one of 

 his illustrations, and I think he mentioned having explained it in 

 some scientific serial. 



Some years ago the late Mr. Becker, formerly scientific fore- 

 man to Messrs. Elliot Brothers, constructed for me a binocular 

 apparatus for showing the union of two shidows, one on each 

 retina. To my surprise I found the resulting phantom did not 

 differ in position from the single shadow. C. M. Ingleby 



Athenaeum Club 



How to Prevent Drowning 

 I ONLY write in the interests of humanity. Let those who 

 will go in for swimming, and I wish sincerely that every one 

 could swim. Treading water however conducts at once to 

 swimming. Every one can tread water who likes. It is just as 

 easy, if we only knew it, to tread water as to tread the earth, 

 and proximately just as safe. Men and women might walk into 

 the deep sea and out again when they pleased. Nature has not 

 been so niggard with us as some persons imagine. Why are we 

 not as safe in water as is the dog ? It is simply because he 

 treads water, and we do not. As often as I chose to chuck my 

 stick into the Causey surge my dog brought it out. I could have 

 done the same ; any one could do the same who chose. But 

 assuredly I should have paddled water as the dog did. In 

 treading water the body is erect, or nearly so ; in swimming we 

 sprawl, and are comparatively helpless. The admirals, both of 

 them, have given valuable testimony as regards the efficacy of 

 treading water. Before the present pier at the Cape was built, 

 vessels in bad weather could not communicate with the shore, 

 even by boats. Men, then, treading water amid the mountain 

 seas, carried coairaunications to and fro in oilskin caps. I 

 have heard it was the same at Madras. Young Gordon, appren- 

 tice to the sea, fell into mid ocean while fisting a sail. The 

 poor fellow's heart sank when he saw the ship sailing away. 

 But, as he afterwards told me, he trod water, and kept up till the 

 boat reached him. I have trodden water again and again with 

 a big boy on my back. Any one might do the same. Not one 

 woman in ten thousand, not one man in a thousand, I suppose, 

 can swim. They do not know they can tread water when they 

 fall in, and of course drown, as two fine young women who had 

 got a little out of their depth in this place did last year. But 

 ignorance and prejudice cannot always rule, and the day will 

 surely come when human beings, better in>tructed, shall enjoy 

 the same immunity in the water that other animal, not human 

 beings, now enjoy. Henry MacCormac 



Bournemouth, June 



Buoyancy of Bodies in Water 

 A propos of the question of drowning, as the same is now 

 raised in Nature, and especially so as to the alleged "fact that 

 men are very different in buoyancy," allow me to say that when 

 stationed many years ago at Pembroke Dock, South Wales, two 

 soldiers were drowned there within a few days of each other. 

 One of these casualties occurred off an island named the Stack 

 Rock, in Milford Haven, that was garrisoned by invalided artil- 

 lery, while the other toDk place in the creek that separates the 

 town and dockyard from the huts. In the former instance the 

 body of the (drowned) man remained floating upright in the 

 water, "bobbing up and down with every wave" — as an eye- 

 witness assured me — for a considerable time, or until it was lost 

 to sight or recovered (I forget which just now). In ihe latter the 

 body — that of a healthy, nniscular man — was picked up a day or 

 so afterwards by a passing boat as it was floating out with the 

 tide to sea ; and I have since seen several fresh bodies floating 

 in the Ganges. Indeed the survivors always attach weights to 

 the remains of even the poorest of their kindred ere they deposit 

 them in that sacred stream ; but this may be for the purpose of 

 counteracting the current ; and it is, I think, generally assumed in 

 books and courts of law that all bodies, human and bestial, sink 

 as a rule in water as soon as life is extinct ; in other words, it is 

 stated that they remain submerged till decomposition sets in, or 

 sets up such an amount of gas within them as enables them to 

 ofercome all resistance from above, and float. If such be the 

 case we must either suppose that the corpses referred to within 

 possessed some special attributes of their own, or that "men 

 are very different in buiyancy " after death than they were during 



life. Assuredly these men could not have been lost in this way 

 h.ad their bodies been able to float in the one state as well as they 

 were in the other ; and I heartily agree with Mr. Hill when 

 he says that ' ' no amount of coolness or presence of mind will either 

 supersede the art of swimming or alte." the laws of gravity." 

 Ashton-under-Lyne W. Curran 



Resonance of the Mouth-Cavity 



The observation of Mr. John Naylor, forwarded to you by 

 Mr. Sedley Taylor (p. 100), admits of being made with more 

 striking (because louder) results than by the method described, 

 and so f^ar from bemg a "discovery," is well known to most 

 schoolboys. Tap with the thumb-nail upon the front teeth, and 

 at each tap alter the shape of the mouth-cavity so as to produce 

 the note desired ; any tune may then be played loud enough to 

 be heard at the other end of a large room. It is remarkable 

 that without previous practice one instinctively shapes the mouth- 

 cavity so as to produce, in almost every case, the exact note 

 required. George J. Romanes 



Thunder-storm at the Cape 



A YOUNG man of my acquaintance, who some time ago joined 

 the Cape Mounted Rifles, has just forwarded to me an account 

 of a severe storm which occurred on the evening of Thursday 

 last, April 14. C. Tomlinson 



Highgate, N., June 13 



" The storm set in about 6 p.m., whilst the men were at 

 stables, and was accompanied by loud thunder and vivid flashes 

 of lightning. At 6. 1 5 there was a fearful roll of thunder, accom- 

 panied by a most vivid flash, which lit up the square for at least 

 thirty seconds. It struck the barracks at the upper end, ran 

 past a room to the stables, which have iron roofs ; it ran along 

 the course of the roofs into the stables, striking down two men 

 in the doDrway. It then ran along the iron of the manger, 

 flooring all the horses, nineteen in all, and so went to ground. 

 One man was struck in the left shoulder bone, the fluid passing 

 from there under the left arm to his watch in the left-hand 

 trousers pocket, and burnt a hole clean through the silver case. 

 From the watch it struck again six inches below, and tra- 

 velled round the leg under the knee, and from thence probably to 

 the spurs, as no burn was found below the knee. The extremi- 

 ties of both tracks were marked by large burns, and each track 

 by a burn two inches over. The surgeon says it was the most 

 miraculous escape he ever saw, the watch having saved the man's 

 life. The second man was merely stunned, and lost the use of 

 his legs for some hours ; he was standing in the stable behind 

 the first, and although only slightly burnt, is still unable to walk. 

 The other is doing well, but is rather dazed. Ten other men were 

 floored, but soon regained their legs. As to the horses, one 

 i\as struck dead in the forehead : two others, blind in both 

 eyes, were shot yesterday ; and four more blind in one eye are 

 condemned. A horse in town was struck, and Jiis fore-leg 

 broken in four places. 



' ' Within a hundred yards of the barracks is a powder 

 magazine full of powder, fitted with conductors which were 

 struck several times. This occasioned great alarm to the in- 

 habitants, as it contains many tons of powder. 



"John P. Cunningham 



"King William's Town, South Africa, April 18" 



A Six-Fingered Family 



It may interest some of your readers to hear that there is at 

 present living in Brown's Town, Jamaica, a family in whom the 

 possession of six fingers has been hereditary for at least four 

 generations. Unfortunately they consider the sixth finger a 

 deformity, and always amputate it, so that there is very little 

 opportunity of observing it. There is a little girl there however 

 upon whom this operation has not been performed, and I much 

 regret that, as her parents had taken her up into the hills to work 

 in their provision grounds, I could not see her. As I am in- 

 formed, the sixth finger springs from the little finger knuckle 

 at right angles to the little finger, and when it is free of it, it 

 turns up parallel to the rest, being a little shorter than the little 

 finger, but quite perfect, with nail and two joints. It is bent 

 and extended with the rest on opening or closing the fist. 



Another fact, which I daresay however is usual in such cases. 



