264 



NATURE 



\jan. 22, i\ 



the Pampas. During the long periods of droughl which are so 

 great a scourge to the country, these animals are starve:! by 

 thousands, destroying, in their efforts to live, every vestige of 

 vegetation. In one of these siccos, at the time of my visit, 

 n 1 less than 50,000 head of oxen and sheep and h jrses p irish 1 

 from starvation and thirst, after tearing dsep out of the soil 

 every trace of vegetation, including the wiry roots of the Pampas 

 grass. 



Under such circumstances the existence of an unprotected 

 tree is impossible. The only plants that hold their own, in 

 addition to the indestructible thistles, grasses, and clover, are a 

 little herbaceous oxalis, producing viviparous buds of extraor- 

 dinary vitality, a few poisonous species, such as the hemlock, 

 and a few tough, thorny, dwarf acacias and wiry rushes, which 

 eren a starving rat refuses. 



Although the cattle are a modern introduction, the numberless 

 indigenous rodents must always have effectually prevented the 

 introduction of any other species of plants, large tracts are still 

 honeycombed by the ubiquitous biscacho, a gigantic rabbit, and 

 numerous other rodents still exist, including rats and mice, 

 Pampas hares, and the great nutria and carpincho on the river- 

 banks. That the dearth of plants is not due to the unsuitability 

 of the subtropical species of the neighbouring zones, cannot 

 hold good with respect to the fertile valleys of the Andes beyond 

 Mendoza, where a magnificent hardy flora is found. Moreover, the 

 extensive introduction of European plants which has taken place 

 throughout the country has added nothing to the botany of the 

 Pampas beyond a few species that are unassailable by cattle, 

 such as the two species of thistle which are invading large dis- 

 tricts, in spite of their constant destruction by the fires which 

 alwiys accompany the siccos. Edwin Clark 



Marlow, January 15 



Japanese Magic Mirrors 



In your last week's issue (p. 24.9) appears a 'paragraph from 

 a paper by Dr. H. Muraoka of Tokio on "The Magic Mirror 

 of Japan," and reference is made to the interest these mirrors 

 have excited, and the large number of writers and lecturers who 

 have taken up the subject of their construction. I have read 

 most of what has been written and stated upon the subject, and 

 dissent from all that has come under my notice, especially the 

 ingenious theories of non-continuous convexity of surface. My 

 reason for dissent is that I have seen one, and for some time it 

 was placed in my care by a friend who made it himself in this 

 country. 



He, and I have no doubt correctly, assumed that the differ- 

 ence in reflection was due to difference of density, and that by 

 hamnering the flat surfaces if the large letters on the back of 

 the mirror, an increased density would be produced which would 

 extend to the front of the mirror, which would then receive a 

 slightly higher polish, sufficient to give the magical figures. 

 From this reasoning he concluded that any metal which could 

 be polished so as to reflect well could be treated in the same 

 way with the same results. 



His first experiment was with a half-crown piece, and the 

 success was complete ; he had the reverse rubbed down, until a 

 perfectly smooth and polished surface was produced, the 

 reflection from which, on white paper and with a strong light, 

 showed the head of the obverse quite distinctly, but differing 

 from the ma.dc mirrors in this respect, that it was less bright 

 than th~ other portion of the disk, because the coining-press 

 would bring its greatest pressure upon the field and not upon 

 the type. T. C. A. 



Edinburgh 



Peculiar Ice-Forms 



I inclose a letter with which I have been favoured giving 

 another case of the curious ice-structure lately described in 

 Nature. The circ imstances are very similar to those of the 

 other cases. B. WoODD SMITH 



Hampstead, January 16 



Fluent Road, Leicester, January 13, 1885 

 Dear Sir, — "rav excuse my troubling you with an extract 

 from my note-boo': as to a peculiar form of ice which I saw on 

 the morning of September 21, 18S0. I started to descend from 

 the M ggi h M-n h del a little before 6, and when I suppose that 

 I wa abou 1 sand feet down, just before coming to the 

 wood, I notic 1 e curious-looking ice just along the bottom 



of the sloping sides of the path, which here runs in a shallow 

 gulley two or three feet deep. The ice ran along the side of the 

 path for some yards. I took up several pieces in my hands and 

 examined them, and made a rough sketch, which I reproduce 

 without any additions. The ice was made up of bundles of little 

 rods about one-sixteenth of an inch in diameter and half an 

 inch long. They were roundish and rough or fluted on their 

 sides, and tapered at each end, and in some cases the ends 

 finished with a little thread .f ice about a quarter the thickness 

 of the body of the rod. The rods stuck together and were a 

 little curved, and formed roughly two layers, or tiers, one above 

 the other. My note states that these bundles of ice-rods lifted 

 up the dirt and small stones on the top of them. The day before 

 there had been snow with a thaw. 



My ini| ression was at the time that water, rising through the 

 ground and being frozen just before it reached the surface, gave 

 rise to these peculiar ice-forms. 



You are quite at liberty to make any use you please of this 

 note. I am, dear Sir, yours faithfully, 



John D. Paul 



Iridescent Clouds 



The iridescent colours in clouds, observed in England and 

 Scotland in December last, were also visible here December 8, 9, 

 10, and 12. On the first day, about 3 p.m., the coloured clouds 

 were arranged in a horizontal layer about 20 high, between 20° 

 and 80 ° azimuth west. In the half altitude a fine stripe broke 

 forth from the background of the ordinary (but not dense) cumulo- 

 stratus. 



The opinion of one of your correspondents that a connection 

 exists between this and the sky-glows of the last two years, is 

 contradicted by the circumstance that the phenomenon has been 

 observed here several times before, viz. 1871, February 22, 

 March I, May to; 1874, January 13; 1875, February 17; 



1881, December 27; 1882, January II, February 22, July 13. 

 I make the following extract from the observation of 1882, 

 January II, showing the peculiar changes in the colours: — at 

 3.30 p.m. (sun set at 3.20) extremely beautiful iridescent cirro- 

 stratus in south-west, in an altitude of 8° — 12". The upper 

 borders, later also the lower, were red, with yellow brims, the 

 rest of the borders and the inner parts very variegated and 

 variable ; the light red, commonly seen in mother-of-pearl, 

 changed through crimson into blue-green, and then into grass- 

 green. On some spots this change was repeated twice. The 

 variation of the colours continued till after 4 o'clock ; at 4.30 the 

 colour was the ordinary red. The form of the clouds varied 

 very slowly. 



1881, December 27, an isolated brilliantly-coloured cloud was 

 observed through two hours at least. A drawing of it by Dr. 

 Reusch (in woodcut) is inserted in the Norwegian Nature n 



1882, No. 1. 



The most striking cases of this phenomenon have been ob- 

 served here when mild and dry weather set in after frost. 



H. Geelmuyden 

 University Observatory, Christiania, January 11 



Solar Phenomenon 



As I see no record of what I witnessed on the afternoon of 

 the 14th instant in Nature of the 15th, I trouble you with this 

 brief statement. At 3I1. 20m. p.m. on that day I was struck by 

 the appearance of the sun, which was crossed by a light stratus 

 cloud of a clearly-defined outline, below which appeared what 

 seemed a column of light of uniform width, down to the horizon, 

 the width being somewhat less than the sun's diameter. By 

 3h. 30m. the definition of this parallel beam was less marked, 

 but the sun presented to me the appearance of an oblong, sug- 

 gesting three partially-superposed disks. Soon afterwards the 

 sun was wholly obscured. The day had been cold, the tempera- 

 ture being never far from freezing-point in the shade. I have 

 on former occasions, and in summer, seen the parallel beam 

 striking upwards, once in association with a mock sun. 



Valentines, Ilford C. M. Ingleby 



A Cannibal Snake 

 With reference to notes as to Ophiophagous snakes, which 

 appeared at pp. 216, 269, 312, and 40S of the last volume of 

 Nature, I inclose a communication received by me this morn- 



