Dec, 19, 1878] 



NATURE 



J 47 



" In the undulating region of Travancore, where the water- 

 bearing strata heave and fall according to the locality concerned, 

 I have come across a set of professional men who are generally 

 consulted by those who wish to sink wells in view to ascertain 

 whether, at a given spot, a well may be sunk with the pro- 

 bability of finding water near enough. These professional 

 men imdertake to predict where the springs will be 

 found near, and where they will be found at great depth, 

 and their predictions are generally verified with great accu- 

 racy. I took some trouble to ascertain how these men 

 are enabled to predict the proximity, or otherwise, of the springs 

 underground. Brushing aside the ceremonies and incantations 

 they perform in view to deceive others and perhaps themselves 

 also, I found that they detect the proximity of the subterranean 

 springs by lying down on the bare ground in the dead silence of 

 night, with the ear in contact with the ground, and trying to 

 hear the sound of the flow of water in the strata beneath. By 

 practice the ear is made very sensitive, and the d^ree of 

 distinctness with which they hear the sound of flowing water 

 enables them approximately to predict the depth of the springs. 

 It is in this manner that appropriate spots are selected for 

 sinking wells. 



"Now, would any of the instruments you are experimenting 

 with magnify the sound of the subterranean flow of water so as 

 to greatly facilitate the process I have described ? If so, it may 

 be a considerable practical gain." 



To this query I have hitherto been able to return no other 

 answer than a negative one. Both the subjects are practical 

 ones, and I only hope that there will bebefore long some light 

 cast upon them. Thos. S. Tait 



Baroda, India, November 4 



Leaf-Sheaths and the Growth of Plants 



The latest results of M. Bert's researches into the growth of 

 plants (see Compies Jiendi^, vol. 87, p. 695, November 4), have 

 led me to publish an observation which I made on the inner 

 sheaths of young leaves this last spring. The spring before last 

 I was struck with the crimson-like colour of these silky sheaths 

 on many trees, whereas the young leaves they cover are of a 

 tender green, and it naturally occurred to me that their piirpose 

 was not only to form a wrapper to the leaf, but also a coloured 

 screen, which would allow the red rays of the spectrum to pass, 

 and to a certain extent quench the blue rays. But I could not 

 understand why the latter rays should be cut off, since they are 

 highly actinic, and the leaves themselves are green. Last spring 

 I carefully noted the tints of the leaf -sheaths of difierent trees, 

 with the following results : — 



Name of Tree. 



Elm 



Lime 



Beech 

 Sycamore ... , 



Ash 



Horse-chestnut 

 Maple ... . 



Birch , 



Oak 



The Bramble 

 The Hawthorn 

 Certain Roses 

 Wild Cherry 



Tint of Inner 

 Leaf Sheath. 

 Red (crimson) 

 Red (crimson) 

 Red (crimson) 

 Red (crimson). 



Tint cf Cuter 



Leaf Sheath. 



Reddish-brown. 



Reddish-brown. 



Brown. 



Sooty-black. 



Red (crimson). 



Bright -red. 



Brown. 



Brownish-red. 



Reddish. 



Red. 



Red. 



Red. 



Sometimes the bark on the stem of young sycamore shoots 

 and the top leaflets were tinged with a deep reddish-brow n. The 

 overlapping tips of young leaves in buds were frequently reddish, 

 and the majority of outer leaf-cases were a warm or reddish- 

 brown. The shining buds of the horse-chestnut afforded a fine 

 example of the phenomenon. The leaf -cases were of a strong 

 red, like carmine, the exposed tip of each sheath leaflet being 

 dyed a deeper red at the middle, shading off to the edges, where 

 they overlapped. Under this protective curtain was a l-iyer of 

 ' jssy fibre, like cotton, swathing the pale young leaves under- 

 ..eath. 



The recent researches of M. Bert throw light on this interest- 

 ing subject. He finds that plants kept under green glass shades 

 soon perish, because these intercept the red or less refrangible 

 rays of the spectrum, and allow the blue or more refrangible 

 ray^ to pass. Red glass, on the contrary, sustains life, although 

 It becomes enfeebled by reason of the withdrawal of all the blue 



rays. M. Bert thinks that all the rays are necessary to the fell 

 vigour of the plant, and in the proportion of the solar spectrum. ; 

 but it would appear from the care which nature has taken to 

 redden the young leaf-case«, that for certain trees mX least, the 

 spring sunlight is richer in blue rays than she wishes, and there- 

 fore she has arranged that part of them shall be excluded, while 

 all the red rays (or those which affect the maximum reduction of 

 carbonic acid gas, and the building up of tissues) are allowed k> 

 pass into the leaf. I should add that this effect of colour is 

 evidently superadded to the other functions of the sheath, as it 

 usually appears as a more or less perfect colouring of the ottfer 

 surface of the sheath only. John Munrcv 



West Croydon 



Hornets 



The following fact, which I have been enabled to verify cart' 

 ceming a hornet, may be interesting to some of the readers o#^ 

 Nature : — In a letter I received from my grandson, a very 

 observing and accurate young naturalist, there was the followiag" 

 statement, dated October 13, 1878, Tunbridge WeUs : — 



"Last week I caught a splendid large hornet on the hall 

 window, and last Saturday I caught a smaller one on a small 

 oak-tree in Hurst Wood (Tunbridge Wells). He was engaged 

 in eating some sticky, whitish stuff^ which had come out of tie 

 tree in several places where it had been cut or bruised. This 

 stuff" seemed to attract all the insects in the neighbourhood, 

 especially swarms of flies. There were two red admirals (butter- 

 flies), two hornets, four wasps, and hundreds of bluebottles and 

 other small flies, busily engaged in eating this substance, which 

 was bored with small round holes. On Sunday, as we came home 

 from Speldhurst Church, we passed the same tree, and on it, to 

 my great siu-prise, I caught half a hornet, which was very active, 

 running about the tree, and seemed to be quite happy and com- 

 fortable. He had no abdomen at all, except a small piece of 

 the upper skin, which hung on ; his left wings were very much 

 battered, and he had lost his left hind leg. " This half hornet 

 was brought home and examined, keeping actively alive until the- 

 evening, when it was destroyed for the sake of preservation. I 

 had an opportunity of examining the half hornet alluded to very 

 soon after, and the facts detailed in the letter I have quoted were 

 ascertained to be quite correct. This hornet was a small speci- 

 men, and I found all the abdomen gone except a small portioa 

 of the upper part of the first joint, which still remained attached 

 to the thorax. The left wings were much broken, and one hind 

 Ifg gone. In this disabled state, how long the hornet might 

 have lived is a point which I regret was not ascertained. 



Raystead, Worthing Wm. Wilson Saunders 



Equine Sagacity 



A PLEASANT story has just come to us from the Cape of Goo5 

 Hope. In Graaf-Reinett, as in all the old Dutch towns in the- 

 colony, there is, in the centre of the place, a large markeC 

 sqtiare, where the farmers, traders, and others, arriving with 

 their produce at any hour of the day or night, may "out-span" 

 the oxen or horses from their waggons, send the cattle out 

 to the "commonage" to feed, while they bivouac at their 

 waggons, as is the wont of African travellers to do, until the 

 eight o'clock morning market auction. 



An old horse belonging to one of these parties had wandered 

 about in search of grass and water — vainly, no doubt, for it was 

 during the severe drought from which the country is but now- 

 recovering. Coming to the great bare market-place, and finding 

 a knot of men talking there, he singled out one of them, and 

 pulled him by the sleeve with his teeth. The man, thinking the 

 horse might possibly bite, repulsed him, but as it was not very 

 roughly done, he returned to the charge, with the same recep- 

 tion ; but he was a persevering animal, and practically de- 

 monstrated the axiom that "perseverance gains the day," for 

 upon his taking the chosen sleeve for the third time between his 

 teeth, the owner awoke to the idea that a deed of kindness 

 might be required of him ; so, putting his hand upon the horse's 

 neck, he said, " AU right, old fellow ; march on ! " The horse 

 at once led the way to a pump at the fiu-ther side of the square. 

 Some coloiured servants were lounging about the spot. ,One cf 

 them, at the bidding of the white man, fiUed a bucket with 

 water ; three times was the bucket replenished and emptied 

 before the "great thirst" was assuaged, and then the grateful 

 brute almost spoke his thanks to his white friend by rubbing his 



