February 23, 191 1 



NATURE 



541 



since, that the calcium photographs have a hard, skeleton 

 look about them. In hydrogen Ho the same prominences 

 look more full, and are overlaid by extensive crowns or 

 strata of clouds of varying brilliance, which \ cannot find 

 in the corresponding calcium pictures. Thus this promin- 

 ence also appeared much higher in the radiations of Ha 

 than the calcium spectroheliograms show. In the case 

 under discussion, the prominence was chiefly remarkable 

 bv virtue of its enormous extent in latitude, spanning as 

 it did right across the equatorial regions from P..\. 37 to 

 P..\. 84, encircling thus more than 45 degrees of arc 

 practically along an imaginary meredianal line. 



It is here where the spectroheliogram taken by M. 

 Deslandres on March 21 comes in, showing as it does this 

 remarkable prominence as a pronounced dark calcium and 

 hvdrogen flocculus a few days distant from the east limb. 

 This dark formation conforms in the direction and magni- 

 ture of its principal dimensions to the bright structure 

 seen a few days before on the eastern limb. Not only 

 this, but it shows by its pronounced convexity towards the 

 •west palpable evidence of equatorial acceleration. Further- 

 more, it shows along its western contour a bright ribbon, 

 just as one would expect to see if the brighost portion of 

 the prominence was allowed to peep from under an over- 

 ling dark or absorbent stratum for reasons of perspective, 

 ■which in that longitude would be considerable. This is 

 strikingly visible on the glass positives, a fine specimen. of 

 which M. Deslandres exhibited at London. 



It remains to be recorded as another remarkable feature 

 of this same prominence (by no means infrequently seen 

 bv me before and since) that along its top • it :seemed to be 

 ciit off along its entire length by an unbroken 'and sharp 

 line when seen in Ho, giving the distinct »impression> that 

 the entire structure was overlaid by a dense, dark, absorb- 

 entlv acting mass of vapours, some other outlines of which 

 under conditions of best definition could be made out, as 

 I pointed out in my recent contribution to solar research 

 In Ihe Observatory. The -dark flocculus depicted in M. 

 Deslandres' spectroheliogram does in the present case un- 

 doubtedly show that hypothetical dark overlying stratum, 

 ■which therefore is situated at very considerable height 

 above the sun's general surface. The prominence per- 

 sisted to show this abrupt upper termination during 

 successive appearances, but this was not so apparent when 

 It was last seen in the west on .April 28. but even then- 

 dark masses were seen projected on the luminous back- 

 ground afforded by the prominence itself. 



Albert .Alfred Bess. 



Chorlton-cum-Hardy, February 16. 



Vibrations of a Piaooforte Sound-board. 



While investigating the vibrations of the pianoforte 

 sound-Hoard, a curious result was obtained a short time 

 tgo which it is perhaps worth while recording. 



One leg of an optical lever was attached to the sound- 

 board of a pianoforte at a point 3"-; cm. below the frame 

 suoDorting the keys and 9 cm. on the treble side of the 

 bridge. A beam of Heht from an electric ate fall$-on a 

 concave mirror attached to the ootical lever and ts Reflected 

 to, the drum of a phonogrraph. The combined vibrations of 

 the beam of light, set in motion by the sound-board, and 

 the rotation of the drum trace out a time-displacement 



in both cases, 68 cm. per sec. It will be noticed that 

 No. 2 gives only the second partial of the note struck. 

 This was so unusual that it was thought some mistake 

 had been made, and the apparatus was again connected 

 with the same point of the sound-board. No. 3 shows the 

 curve obtained for a' and No. 4 that for a, thus confirming 

 the f)revious results. 



It is remarkable that a point can be found on the sound- 

 board which responds so well to the second partial of a 

 particular note that the fundamental is apparently entirely 

 excluded. G. H. Berry. 



14 City Road, London, E.C., February 3. 



Occurrence of Maionia sarnientosa in Sarawak. 



While resident in Sarawak I received several inquiries 

 with regard to the conditions of growth of Matonia 

 sarnientosa. Baker. As I can find no published record of 

 this, the following note will be of interest to pterido- 

 phylogrsts. 



it was first found by Dr. Charles Hose hanging from 

 the roof of a limestone cave at Niah, in the Baram Resi- 

 dency, Sarawak ; this was supposed to be the only locality 

 in w^hich it occurred, until it was recently discovered by 

 myself to be growing also on the limestones at both Bau 

 and Bidi in Upper Sarawak. Although some 300 miles of 

 jungle separates this district from Niah. there are, I 

 believe, isolated limestone outcrops on which, when careful 

 search is made, it will possibly be found, thus accounting 

 for its erratic distribution, but it has not been found on 

 the limestone at Quop. which has been well searched. 



This limestone formation is considered to be Jurassic by 

 Mr. J.. S. Gilkie, and is an extremely hard and fine- 

 grained type, but as the fern does not grow on the original 

 rock,, this can only influence its growth by providing suit- 

 able temperature and moisture. In the immediate neigh- 

 bourhood of these immense masses of limestone a cooler 

 atmosphere is noticeable. 



I have never observed this fern grow^ing below 5P feet 

 above the ordinary ground-level : its range may extend to 

 an altitude of 200-300 feet, and then only on the rough 

 and somewhat soft surface of a stalagmite or when the 

 surface of the limestone has received a deposit of calcium 

 carbonate from solution. The position occupied by the 

 clumps is always open and ain*' ; the direct sun rays do 

 not app>ear to be detrimental, but it is invariably sheltered 

 bv an overhanging cliff from the rain. When the con- 

 ditions are all favourable, it grows in ver>- large masses 

 out of all proportion to its slender root -hold : this renders 

 its detachment from the rock easy, but its inaccessible 

 position, makes it one of the most difficult of ferns to 

 collect; and this can only be done bv the aid of Dyaks 

 clever at constructing ladders and scaffolding. 



It is fnteresting to note that, of all the ferns peculiar to 

 this limestone, in its choice of situation it is the most 

 highly developed. Cecil J. Brooks. 



Drinkstone, Bury St. Edmunds. 



Glacial Erosion. 



Your reviewer states that *' the passage of ice over the 



British uplands swept away all the loose rock materials and 



re-deposited them in the lowlands as glacial drifts." I 



presume that the loose rock rftaterials 



are supposed to have been produced by 



pre-glacial weathering. Now, weathered 



rocks are in ver>- many cases easily 



recognised, and my own experience of 



the rocks contained in boulder clays is 



that they very seldom indeed show any 



signs of weathering whatever. The 



boulders are of fresh hard rock which 



has been removed bv the ice. 



R. M. Deelev. 

 Inglewood. Longcroft Avenue, 

 Harpenden. February 10. 



curve of the vibration on a strip of photographic film 

 fastened round the drum. For a full description of the 

 apparatus see the Phil. Mag. for .\pril, iqio. 



Four curves are enclosed. No. i was produced by 

 striking the note a' on the pianoforte. No. 2 by striking a 

 the octave lower. The speed of the drum was the same 



NO. 2156, VOL. 85] 



Materlals loosened by pre-glacial weathering which are 

 weathered throug'hout are naturally reduced to powder alike 

 by glacial and by river transport : but any block which is 

 only partly weathered through would loose its weathered 

 crust and the nucleus would be- left as a fresh hard boulder. 



J. \y. G. 



