August 15, 1895 J 



NATURE 



573 



The Meteorological Office has received through the Colonial 

 I iffice a report from the Governor of Hongkong, according to 

 vvliich it appears that the colony was recently suflfering from a 

 i;rcat ilroiight ; the rainfall from January I to June 23 last having 

 luen only \y; inches, being a deficit of no less than 2S7 

 inches on the mean of the corresponding period of the previous 

 ti\'c years. The (iovernor draws attention to the fact that 

 ' clween October 1893 and April 1894, the colony suft'ered much 

 I mm want of rain, and that the |)lague of the latter year was 

 ~ii|iposed to have originated from a deficient water supply. 

 Though the drought of the first half of this year has been far 

 more serious than that of 1893-94, the plague has not yet rc" 

 appeared in an epidemic form ; but the reservoirs had, at the 

 (late of the despatch (June 26), only about a week's supply left 

 ill ihem. Krom a return furnishe<l by the Director of the Hong- 

 kong f)bservator)', it appears that the greatest deficiency has 

 occurred during May and June, when it amounted to 11 and 124 

 inches respectively. 



La Teihnologie Sanilaire is the title of a nev\ journal devoted 

 lo questions of water supply and applied hygiene. It is pub- 

 lished in Louvain, and is edited by a civil engineer, N'ictor J. 

 \ an [.int. The first number, amongst other contributions, con- 

 tains an interesting and useful article by M. Ad. Kemna, the 

 uell-known Director of the .\ntwerp Waterworks, on "The 

 Theory of .Sand Filtration." The practical genius of the English 

 in the past is emphasised in commenting upon Simpson's intro- 

 duction of sand filters in London in the year 1839, and we are 

 tokl that having produced such brilliant results, it is not 

 surprising that as a nation we are so slow and reluctant to adopt 

 more modern methods and change our system of technical 

 instruction ! Besides original articles, reviews of books are also 

 a|ipended, and what, perhaps, is one of the most useful features 

 of this undertaking, is the bi-monthly issue of a supplement, 

 international in char.act«, containing a bibliography of books, 

 pamphlets, &:c., published on subjects connected with water 

 supi'lj', together with short notices of public hygienic enterprise 

 in dift'erent parts of the world. 



Im RA-KEl) light is invisible to us either because the humours 

 Composing the eye are opaque to it, or because the light is in- 

 capable of exciting the retina. Cima and Janssen have adopted 

 the former explanation, but the alternative one has been accepted 

 liyTyndall, F.ngelniann, and others, while Helmholtz maintained 

 tliat the strong absorption suftered by infra-red rays in their 

 passage through the eye is sufficient to account for their in- 

 • iiiibility. That they are strongly absorbed has been found by 

 all observers, but Herr K. Aschkinass proves, in the last number 

 of Wiejeinaiin' s Aiinalcii, that there is no sudden increase of 

 absorption beyond the red end of the spectrum, and that the 

 absorptive powers of the various media of the eye are practically 

 the same as that of water. The apparatus used for this investi- 

 gation contained a fluor-spar prism and a liolometer. Thin 

 layers of the humours of an ox eye and a human eye were inter- 

 posed in the path of the rays from a zircon burner, and the 

 absorptive eflects noted by means of the bolometer. It was 

 found that at a wave-length of o'Sl ^, the limit of the visible 

 siiectrum, the absorption was 5 per cent, for the whole human 

 I eye. This increased to lO'S pei; cent, at o'872, reached 60 per 

 I cental 0-98, decreased to 345 |ier cent, at 1-095, and finally 

 reached 100 per cent., ortotal absorption, at I '4 fi. This shows 

 that a large proportion of infra-red light fdoes reach the retina 

 through the eye, but is not capable of aftecting the nerves and 

 pro<lucing visual sensation. 



TuR last number of the Wisscnsihafllichc Bciliefle ziim 



DeiilSi/ieii Kolonialhlalte (Bd. viii. Ht. 2) is a further illustration 



of the care with which the German Colonial Society is organising 



the scientific investigation of German .\frica. The present 



NO. 1346, VOL. 52] 



number contains the calculations by Dr. Fritz Cohen, Dr. I.. 

 Ambronn, and Dr. \V. Brix, of the astrontjmical observations 

 made by Dr. Griiner in Togo-land, and by Ramsay and Stuhl- 

 mann in German East Africa. There are also valuable tables of 

 meteorological observations, made in German South-West 

 Africa, and in Kondeland, and from the Marshall Islands : from 

 the last locality comes an especially useful table showing the 

 diurnal variation in atmospheric pressure, and giving the mean 

 reading for every hour for each month in the year. Preuss con- 

 tributesa report on the geography of the Smaller Cameroons, 

 and Steinberg one on the diseases of the natives of the Marshall 

 Islands. There is also a detailed study, by Dr. O. Warburg, of 

 a beetle {Herpetophygas fasciatiis) parasitic on the coffee trees in 

 German East Africa. A good plate shows the insect in its 

 various stages, and also illustrates its ravages on the trees. 



Herr Oscar Nei^max.n has published a preliminary account 

 of his recent important expedition across Masai-land to Uganda 

 in the last number of the VerhaiiJlungi:it ili'r Gesellsihaft fin- 

 Enikimde ztt Berlin (Bd. xxii. No 4-5). Herr Neumann went 

 out to East .\frica in November, 1892, and after spending some 

 months in preparation there, left for the interior on -\pril 27, 

 1893. The caravan, consisting of 135 men, started from Tanga, 

 and passing the southern border of the Usambara country, 

 crossed Nguru to Irangi. Here a series of accidents, exhaustion 

 of supplies, and some severe fighting with the natives, during 

 which Herr Neumann was wounded in the mouth by an arrow, 

 comjielled the expedition to retreat southward to Mpwapwa. 

 After resting there the party went northward across Irangi to 

 the Gurui IMountain. This was ascended, though with consider- 

 able difficulty. Upon the higher slopes an interesting series of 

 Alpine plants were found, including Azalea and Rhododendron. 

 No trace of a crater remains near the summit, but some small 

 craters occur in an adjoining \alley. FVom Gurui the expedi- 

 tion followed up the East African Rift \'alley, along Bau- 

 mann's route past the salt lakes of Manyara and Natron. 

 He examined the volcanoes Doenyo Kavinjiro and D. Ngai ; on 

 the latter he found a steam vent below the summit. F'rom this 

 point he followed Fischer's track past Nguruman to the south- 

 west of the volcano of Suswa. Thence he turned westward to 

 the shore of the \'ictoria Nyanza in Kavirondo, where the 

 expedition again had great difficulties with the natives. Marching 

 round the Nyanza through Usoga, he reached Uganda, but the 

 excessive caution of an English oHicer prevented his reaching 

 Mt. Elgon. From Uganda, which he describes as unhealthy and 

 poorer than Usoga, he returned along the English road, across 

 .Mau, and past Naivasha and Machakos to Kibwezi, whence he 

 diverged to Taveta, and Kilima Njaro, and thus back to the 

 coast at Mombasa, where he arrived on February 5, 1S95. ^'1*^ 

 zoological collections inade are very extensive, including 600 

 species of birds, 90 species of reptiles and amphibia, 50 species 

 of mollusca, and about 1000 species of insects, and 90 species of 

 mammals, of which fi\e have been described as new by 

 Matschie. 



Dr. Otto Kinizk has recently issued, under the title of 

 " Geogenetische Beit rage " (Leipzig, 1895, 7^ PP-)> '^ series of 

 papers dealing with various geological problems, on which his 

 journeys have thrown light. The first paper gives the evidence 

 for some oscillations of level in the .\ndes, based on the inclina- 

 tion of some beds of iron-stained sands and laterite, and on the 

 distribution of plants. He states the evidence with care, as it 

 shows that the alterations of level have occurred quietly and 

 without any sudden catastro|)hic changes. .\ second paper 

 discusses the evidence on which it is claimed that there was a 

 glaciation in Carboniferous limes. The phenomena, often 

 regarded as a proof of this, is attributed by Dr. Kunlje to 

 wind erosion. He gives a figure showing perched blocks and 



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