5i« 



NATURE 



lJum: 15, 1911 



rapidly when the distaiu"! from the film e."scecded 5 mm. 

 The dried juice retained the action with undiminished effect 

 for months. When the dried films were heated from 

 150" C. to 200° C. they charred, but did not lose their 

 action on the plate. As tiie tem|K,'rature was raised further 

 the power of afTt^rting thi- plates was diminished, as the 

 ash of the juice became white. Even the white ash had a 

 slight action on the plate (potassium salts). 



The introduction of screens between the film and the 

 photographic plate led to notable results. The interposi- 

 tion of tissue paper slightly delayed the action on the 

 photographic plate. Thick black paper (013 mm.) 

 employed by the makers to enclose photographic plates, 

 and found by us impenetrable to the rays from phos- 

 phorescent salts, served only to delay the time in which 

 an image of a definite intensity was formed. The effect 

 was produced through a celluloid screen (0-07 mm.) and 

 through paraffined paper (003 mm.). We were unable to 

 obtain screens of glass or mica less than 002 mm. in 

 thickness. These screens completely protected the plates 

 from action by the film. Screens of aluminium foil 

 0002 mm. thick made no alteration in the intensity of 

 the image of the film. When eight layers of the 

 aluminium foil were superimposed, the density of the 

 image on the plate was increased. 



Examination of the dried material with a zinc sulphide 

 screen failed to show any scintillations due to the o 

 particles. 



When a rapid current of dried air was passed obliquely 

 between the plate and the film at a rate of 300 c.c. per 

 minute the image of the letters on the film was sharp 

 and well defined. The distance between the plate and the 

 film was 05 mm. Any gas or emanation would have been 

 carried along by the current, especially any gas having 

 such a slow action on a photographic plate. 



H. G. Chapman. 



University of Sydney, May 3. J. M. Petrie. 



Musical Sands of Eigg. 



Sl.NCE Hugh Miller's brief reference (" The Cruise of 

 the Betsey "j to the musical sands of the Bay of Laig, 

 Isle of Eigg, much has been done with these, and sand-s 

 of a similar character, to enable us to account for the 

 cause of the phenomenon ; and the interest taken by 

 physicists in certain experiments which I conducted some 

 years ago induces me to offer the results of some further 

 observations for publication. 



There is no musical sand in the Bay of Laig, and, so 

 far as I can ascertain, its sands have^ never been musical 

 within the memory of any inhabitant of the island. At 

 the present time the psammological conditions are such 

 as to preclude entirely the possibility of its existence there. 



In a small bay — about a mile and a half along the shore 

 to the north of Laig Bay — known as Camas Sgiotaig, 

 musical sands occur. This bay is divided into two portions 

 bv a reef of calcareous sandstone jutting out from the 

 cliffs seawards. In both portions, but especially close to 

 the clifTs, a white quartzose sand has accumulated, and 

 this is the only place where musical sands are found in 



The sands are derived from the waste of the calcareous 

 sandstone referred to. In places the grains have accumu- 

 lated in small rifts and cavities in the rocks, and in all 

 such it was found to be equally musical, showing that 

 long, flat stretches of sand are not essential conditions for 

 the selective action of the winds and sea-waves. 



The usual experiments with various vessels and 

 plungers, &c., were carried out in situ, and the musical 

 effects were in all cases much more pronounced than those 

 produced by the Studland Bay sand. 



An extraordinary volume of sound was obtained bv 

 dragging the convex part of a wooden bowl along the 

 surface of the sand patches, one of which was onlv about 

 6 feet square. When the same bowl was partiallv filled, 

 and the sand struck with a wooden plunger, it emitted a 

 noise like the deep bark of a dog, and this could be heard 

 for a considerable distance along the shore. 



These musical sands are only found in ca'm weather ; in 

 the winter the huge waves carrv awav all fine matter, and 

 NO. 2x72, VOL. 861 



only the rocks remain — for which reason we must regardrj 

 it as a fine-weather phenomenon in this island. 



Eigg, June 6. Cecil Cabus-Wilson. 



P.S. — .Since the posting of my letter respecting thej 

 musical sands of Eigg, 1 have read the letter from Mr. 

 Thomas which appeared in Nature of June H. 



Prof. Poynting, I think, informed me of the occurrence 

 of these sands at Barmouth some time ago, and I have 

 found them also at Penally, near Tenby, at l>ongland Bay, 

 and in Swansea Bay. 



I have frequently pointed out that the pitch of the note* 

 emitted from musical sands depends (a) upon the size of 

 the grain, {b) the area of the plunger's striking surface^ 

 and {c) the form and composition of the vessel used. li» 

 some vessels of particular form I have succeeded in pro-; 

 ducing from the same mass of sand, and during the one« 

 thrust of the plunger, notes of both high and low pitch ! 



The vessel containing the sand is first well shaken in 

 order that the smaller grains may settle at the bottom of 

 the mass and the larger ones ^;^^ML top. The plunger i» 

 then thrust sharply upon the ^f^ii^, and coming first in 

 contact with the larger grains, it produces a low note; 

 this merges into a note of higher pitch as the plunger 

 penetrates the mass and reaches the finer grains at the 

 bottom of the vessel. 



As a matter of fact, the notes from all natural musical 

 sands appear to be a cumulative effect due to a combina- 

 tion of high and low pitch within a given range. The 

 only sand which seems to emit a pure and definite note 

 is that which I have produced artificially. 



June 10. C. C.-\A . 



Botanical Research in Ceylon. 



Till-: l.iuT from Cambridge with the above tii.,. , »,i.,.i» 

 appeared in your issue of May 25, has evidently been 

 written without knowledge of the difficulties which have 

 arisen at Peradeniya within the last few years and under 

 a complete misapprehension of my views. 



The letter reproduces, without the context, a single 

 sentence from a memorandum of mine. In this 

 memorandum special stress is laid on the importance of 

 maintaining Peradeniya as a centre of botanical research, 

 and it is suggested that Dr. Willis should remain as its 

 director under such conditions as would allow of his con- 

 ducting botanical investigations which in recent years he 

 has found it impossible to undertake. 



The letter seeks chiefly to justify Dr. Willis's position 

 as a botanist, which has not been called in question. 

 Neither have the services which Peradeniya has rendered 

 to the botanical workers who have visited it been ques-j 

 tioned. 



The sentence quoted from my memorandum refers to the| 

 two principal members of the staff and the difficulties 

 which admittedly have rendered botanical research 

 impossible for them owing to the pressure of other work. 



My suggestion, as a solution of the difficulties which 

 have arisen, was to maintain Peradeniya "as a great 

 reference garden and centre for botanical research in the : 

 tropics " — to reproduce my own words — distinct from, 

 though cooperating with, the Agricultural Department^ 

 which the Government of Ceylon, most wisely, now] 

 desires to establish. Whilst I should have preferred this^ 

 solution, I am satisfied that the decision to incorporate thei 

 Royal Botanic Gardens at Peradeniya with the .Agriculturali 

 Department will secure what the colony chiefly needs in| 

 the interests of tropical agriculture, for the advancement 

 of which the whole community, European and native, 

 so deeply concerned. 



Wynojiam R. DrXSTAN. 



June 3. 



The Extinction of the Egret. 



It will be remembered by those who are interested 

 the protection of the white heron that the feather deale 

 have urged that the breeding haunts, or garzeros, of the 

 birds are guarded, and that the moulted feathers 

 picked up from the ground. From information which hi 

 been sent to me from the National .Association of Audut 

 Societies, based on the sworn testimony of a man wl 



