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NA TURE 



\MarcIi 8, 1877 



would then be gradually removed by the action of rain and 

 running water, while the angular blocks and debris would remain 

 for a very much longer time, until eventually they crumbled 

 down and were carried away in the form of gravel, sand, and 

 mud. As far as one can judge from descriptions, the " stone- 

 rivers " of the Falkland Islands seem to present very much the 

 appearance which such dessicated earth-glaciers might be ex- 

 pected to assume, after their finer materials have been abstracted. 

 The possibility that considerable masses of loose materials, such 

 as a "soil-cap," may have moved en masse, has before now 

 attracted the attention of some observers. Mr. Robert Mallet 

 contributed a paper on the subject a number of years ago to the 

 Journal of the Dublin Geological Society (see vol. v. ) ; and in 

 the Jahrhuch der k.k. geologischen Reichsanstalt, vol. xxii. p. 

 309, will be found an article by Theodor Fuchs, treating of the 

 same subject. James Geikie 



Geol. Survey, Perth, N.B. 



Government Grants to Science 



In that part of the article in last week's Nature on " Govern- 

 ment Grants " which relates to the grant which has been for 

 some years annually voted for pathological inquiries under the 

 direction of Mr. Simon, a statement is made concerning myself, 

 which I fear may convey a false impression as to the relation in 

 which I stand to the Medical Department of the Privy Council. 



Will you allow me to say that that relation is limited to the fact 

 that the pathological investigations in questionare conducted at the 

 Brown Institution by my friend and colleague. Dr. Klein, who de- 

 rives his commission directly from their lordships. I may take the 

 opportunity of adding that the directors of the institution, of 

 whom Mr. Simon is one, are as anxious as I am myself that its 

 resources should be available, not only for this, but for all other 

 purposes connected with the advancement of pathological 

 science. 



In former years, as your readers no doubt know, I have myself 

 undertaken numerous investigations for the department, the last 

 occasion occurring in 1875, but for some time past other and 

 equally important duties have rendered this impossible. 



March 5 J. Burdon-Sanderson 



Tints and Polarisation of Moonlight in Eclipse 



The gradation of the coloured tints on the moon's surface 

 during total eclipse was seen here most clearly last Tuesday. 

 At the middle of the eclipse the surface seemed to be obscured by 

 a dusky disc surrounded by a broad bright copper-coloured rim, 

 of uniform width, following the outline of the moon's edge. Just 

 before totality ceased the surface presented the appearance of a 

 series of coloured crescents having the centres of their boundaries 

 on the line joining the point where ordinary light would soon 

 appear to the moon's centre. 



The order of colour was bright sea-green at the edge, followed 

 by a pale golden tint, then copper tints, deepening to a dusky red 

 or peach-bloom. 



The explanation of these eifects of sunlight in its passage 

 through the earth's atmospliere will be found in Herschel's 

 Astronomy, §§ 421-4. 



The sky generally was free from any but very transparent 

 clouds, and the air keen and frosty with steady breeze. 



Shortly before the middle of totality I examined the light from 

 the moon's surface by means of a double-image prism (made for 

 solar eclipse work by Mr. Ladd) outside the eye-piece of a tele- 

 scope with a 3I inch object-glass. On turning the prism round, 

 with its front surface perpendicular to the axis of the telescope, 

 the two images of the moon, in the parts where they did not 

 overlap, appeared to brighten and darken alternately, inter- 

 changing intensities. The cycle was completed in course of 

 revolution through 180°. This is conclusive as to the polarisa- 

 tion of the light received from the moon during total eclipse. 

 I was unable to determine the character of the polarisation. 

 There will be another total eclipse on August 23, for which I 

 hope to be better prepared. A. Freeman 



.St. John's College, Cambridge, March i 



The Patenas or Grass Lands of the Mountain Region 

 of Ceylon 



Everyone who has travelled through the Central Province of 

 Ceylon must have been struck by the occurrence, apparently 



without sufficient cause, of tracts of grass-land varying from a 

 few perches to hundreds, and sometimes thousands, of acres in 

 extent, in the midst of otherwise interminable jungle. This land 

 is exceedingly poor ; almost without exception it is worthless to 

 the coffee-planter for purposes of cultivation, and incapable of 

 supporting any vegetation except its own acrid mana grass (^«- 

 dropogon schcrnanthus) and a few stunted specimens of Careya 

 arborex and Einblica officinalis. Yet on all sides of it will pro- 

 bably be found a rich forest vegetation that grows luxuriantly 

 up to the very edge of the grass, where it termina<-es abruptly 

 without any dwarfed or stunted undergrowch on the border-line 

 to show that the soil gradually changes from a fertile to a sterile 

 character. Sir Emerson Tennant, in seeking for an explanation 

 of this curious phenomenon, appears to have been completely 

 baffled, for he suggests nothing beyond what is contained in a 

 quotation from Humboldt in reference to the grassy plains of 

 South America, where that great traveller speaks of the destruc- 

 tive custom of setting fire to the v.'oods when the natives want 

 to convert the soil into pasture. One reason, which seems to 

 be quite conclusive against this explanation being applied to the 

 grass-lands of Ceylon, is that cleared forest-land, however 

 neglected and impoverished, does not run into grass such as is 

 found on these Patenas, but into a dwarfish jungle called 

 " chena," and then again, after a considerable period of time, 

 into forest Besides, it very frequently happens that these grass- 

 lands are the very last pieces of ground that one would expect 

 the natives to select out of the forest to bestow labour on in 

 clearing and burning. Another and minor argument against 

 this view is that the natives, whose traditions extend back for a 

 considerable period of time, can give no account of the origin 

 of Patena-lands, as no doubt they would be able to do if their 

 ancestors and themselves were the cause of their existence. Other 

 causes, therefore, than that of human agency must be sought for. 

 One of these I believe I discovered during my residence in 

 Ceylon, and I should be glad to learn whether any of the reafjeis 

 of Nature have noticed the same in any part of the gneiss forma- 

 tion of Southern India, or indeed in any extensive gneiss formation 

 within or without the Tropics. How far this particular cause 

 operates in other instances than the one presently to be men- 

 tioned I am unable to say, but I am inclined to the belief that 

 although it does not hold universally, it nevertheless holds pretty 

 generally in the case of the larger patenas. It must be remem- 

 bered that the mountain region of Ceylon is entirely a gneiss 

 formation, very much dislocated during upheaval, and consisting 

 at the present time of exceedingly deep valleys and precipitous 

 mountain ranges. In this gneissic series occurs a band of half- 

 formed quartzite several hundreds of feet in thickness, to which my 

 attention was first attracted by noticing that below it, i.e., where 

 its debris accumulated, nothing but paten a was to be found, 

 whilst above, where the ordinary gneiss rocks were in a state of 

 disintegration, the jungle and coffee was of a most luxuriant 

 character. This band of quartzite stands out from the ordinary 

 gneiss cliffs in the valley leading from Pussellawa to Kamboda, 

 about twenty miles south of Kandy. It extends for about five 

 miles in the form of a cliff, broken through here and there by 

 ravines. Its upper surface, beginning at an elevation of 4,500 

 feet on the Helbodde coffee estate, dips under the main water- 

 fall at Ramboda, and disappears under the ordinary gneiss at 

 an elevation of about 3,000 feet above sea-level. I'his rock 

 weathers very black, and is distinguishable at a distance of 

 several miles from the ordinary gneiss above it and in its 

 neighbourhood. It seems to disintegrate into little else than a 

 quartz sand impregnated with iron and entirely incapable of 

 supporting the usual forest vegetation with which the district, 

 except in this particular spot, abounds. I have been informed 

 that in the extensive patena district of Ouvah, which, roughly 

 speaking, is a plain almost surrounded by mountains, a few 

 miles south of the district just mentioned, and separated from it 

 by the loftiest mass of mountains in the island, the same 

 quartzite formation occurs, but not having had an opportunity of 

 visiting and examining it, I am unable to say how far this infor- 

 mation is to be relied on. When one remembers how very ex- 

 tensively the gneiss is broken up throughout the whole of this 

 mountain region of the Kandyan province, it seems not improb- 

 able that other patenas, especially the larger ones, owe their 

 origin to the cropping out of this quartzite band, although it is 

 difficult, probably impossible in many cases, to determine that 

 such is the case, 



R. Abbay 

 Oxford 



