Nov. 22, 1883] 



NATURE 



77 



The mangrove has established itself on the edges of the lagoon, 

 doubtless from seed transported by the currents, and, in all 

 places where it has done so, tortuous creeks or little gorges run 

 back into the coral, filled with mangrove trees (standing in deep 

 mud of the adhesive and fcetid nature so characteri^tic of man- 

 grove swamps), which stretch out their roots to the coral walls 

 around them, and, as it seemed indubitably to me, in some way 

 decompose the softer parts and eat their way in. The island is 

 riddled with these creeks, always filled with mangrove, and 

 opening into the lagoon. 



The outer face of the island is of eour;e being slowly under- 

 mined by the sea at high water, presenting overhanging cliffs 

 impossible to scale, and the i'-land is wearmg away fro)n that 

 cause also, but the destruction from the mangrove is much more 

 important, and at no very distant period, as it seemed to me, the 

 upraisi'd island will be again reduced to its original level as an 

 ordinary atoll. 



It would be interesting to know how long the mangrove has 

 been there, for as Aldab'-a is one of the two oceanic groups in 

 which the giant tortoises -till exist indigenous, it must have been 

 in its present condition of upraised atoll, I imagine, i >r a long 

 period. It could never have been much larger in diameter, from 

 the soundings round it, but the mangrove may have greatly in- 

 creased the size of the lagoon by steady working at the inner 

 rim of the islands, the actual area of which is now but small, 

 from their narrowness. 



I may mention that the island is covered with low, tangled 

 scrub, which has managed to find foothold and sustenance on 

 the rock, for there is but little or no siil, and the top of the 

 rock is everywhere cut up by sub-aerial action into the sharp, 

 honeycombed, and jagged surface which upraised coral in the 

 tropics, uncovered by grasses, s>il, &c., always wears in'io, and 

 which, by the way, makes it extremely difficult to walk over, a 

 difficulty much increased in this instance by these mangrove 

 channels, as well as the tough nature of the matted, thorny 

 bushes. A walk in Aldabra is the most aggravating and slowest 

 piece of locomotion I have ever engaged in : and nothing short 

 of the patience, perseverance, and general disregard of time of 

 the tortoise tribe can make it an agreeable residence. Some of 

 my negro sailors were sent into the bush to hunt for tortoises, 

 and after three days' search brought back one, which is now in 

 the Gardens of the Zoological Society ; but they returned nearly 

 OS guiltless of artificial clothing as their captive. 



\V. J. L. Wh.'^rton 



H.M. S, Sylvia, Monte Video, October 10 



The "Cloud-Glow" of November 9 

 The beautiful after-glow of Friday, the 9th instant, was most 

 striking as seen from the west side of Hampstead Hill, where it> 

 fi; St development \^as made more effective by a frame of dark 

 cumulus, with a fringe of dusky green tint, carried up from the 

 sunset quarter by a westerly breeze, rather rolled up like a cur- 

 tain, exhibiting the richly-coloured scene behind as it was with- 

 drawn. I estimated the altitude of the upper edge of the glow 

 at about 30° ; but at Freshwater, Isle of Wight, it has been 

 described as extending nearly to the zenith. There would be no 

 difficulty in calculating apprjximately the height of the cirrus — 

 as desired by Mr. Kussell — if it could be assumed that the 

 reflection was from the same matter in both cases, which is 

 improbable. J- J- Wai ker 



Waking Impressions 



A ct;RIous case I have just read in a recent number of 

 Nature recalls a somewhat similar experience of my own, 

 rather earlier in date. I awoke in the middle of a story told by an 

 internal voice — a voice felt, not heard. I listened with curiosity 

 and interest, as totally unprepared for what was coming as if tlie 

 narrator had been Gladstone or Kuskin. I believe when I awoke 

 I had a dim recollection of wliat had gone before, but I strove 

 afterwards in vain to recall it. All I know of the history of the 

 mysterious lady is the following fragment : " She had many ad- 

 mirers, but she gave the preference to Tom, because he promised 

 to marry her in the \Ve>t Indian fashion. He drew her three 

 times throu:5h a hoop, once standing, once sitting, once lying, 

 which signified that he would never dc-ert her in youth, maturity, 

 or old age." 



I have not the least idea who "she " was. I know no one I 

 call Tom except an old schoolfellow long married, and, to 



the best of my belief, I never heard of sich a custom in the 

 West Indies or elsewhere. Once since I have waked in the 

 middle of a dream which went on, but it was a dream of a very 

 commonplace character. William Radford 



Sidmouth 



Barytes from Chirbury 



I am indebted to Mr. Yelland of Wotherton for sending me 

 some fine examples of the crystals described by Mr. Miers in 

 Nature, vol xxix. p. 29, and am collecting several particulars 

 respecting their occurrence. Some time ago I commenced a 

 determination of the faces, but my work has been interrupted. 



The characteristic plane E is mentioned by Carl Urba (Groth, 

 Zeitschrift fiir Crys'.allographic, v. 433, 18S1) as occurring on 

 birytes crystals from Swoszawice in Galizien. In a measurement 

 I made last year to determine this plane on one of the W^otherton 

 specimens 1 obtained EE'as 39^59', and, usinu Miller's distance 

 for bd leads to the .symbol 412, and by calculation the distance 

 « E as 26" 2'. Carl Urba gives its calculated distance as 26° 4', 

 and measured distance as 25' 58'. C. J. Woodward 



Birmingham and Midland Institute, Birmingham, Nov. 10 



" Salt Rain and Dew " 



Looking over the ".School Geography" of Dr. Clyde (Edin 

 burgh, 1S70), I find, on pa^e 32, in the paragraph headed 

 " Russian Lakes," the following remarkable statement: — "In 

 the south-east region, not only the lakes, bid i/u- vety rain and 

 dcii' lihwise an' sail, a phenomenon common to all the shores of 

 the Caspian and Sea of Aral " (the italics are mine). Will some 

 one of your readers kindly refer me to the traveller's tale in which 

 this myth originated. Harry N. Draper 



Esterel, Temple Road, Dublin, November 17 



AN INDIAN WEATHER FORECAST 



THE period of drought in Upper India, which happily 

 came to an end in the latter part of August, was 

 not entirely unforeseen, as will be shown by the following 

 extracts from the Government Gazette j and the facts will 

 probably be not without interest to meteorologists in 

 Europe and elsewhere. 



Extract from the " Gazette 0/ India'' of June 2, 1883 

 "That the unusually dry weather now prevailing over 

 the North-Western Himalaya, and that which, though less 

 abnormal, characterises the whole of North-Western India 

 at the present time, is an effect of the unusual accumula- 

 tion of snow, is a conclusion justified by the experience 

 of the last few years ; and were it not that the snow is 

 rapidly decreasing under the unobstructed radiation of 

 the sun, there might be some reason, judging from the 

 present limited experience, to anticipate some retardation 

 of the rains of the Upper Provinces, and possibly even in 

 Western India generally. But, on the other hand, the 

 fact that, during the months of .April and May, the atmo- 

 spheric pressure over the greater part of the country lias 

 been below the normal average of the season, is one 

 which, arguing from the same experience, portends favour- 

 ably for the timely influx of the monsoon. In Bengal it 

 may be said that the present prospects are wholly 

 favourable. 



(Signed) " Henry F. Blanford, 



Meteorological Reporter to the 

 Government of India 

 "Simla, May 18, 1883'' 



" Since the above was written, there has been heavy rain 

 for many days on the outer hills, and more or less on the 

 plains of the Punjab, and apparently a very heavy fall of 

 snow on the higher ranges. .'\t the present time, as seen 

 from Simla, the latter are white with snow, down to a level 

 of about 1 1,000 or 12,000 feet. And some 500 feet of the 

 top of the Chor (11,982 feet) is also covered with a snow- 

 cap. If, therefore, the mountains of Lalwul, Spiti, and 



