136 



NATURE 



[December 12, 1895 



another tangentially, do so at marked angles, and are therefore 

 not truly perlitic ; while he shows how these also can be 

 imitated artificially. Reasons are given for doubting the 

 perlitic character of cracks in lithoidal rocks claimed as such, 

 and finally the author considers it "extremely improbable that 

 a crystalline aggregate, consisting of individuals with various 

 cleavages and different coefficients of contraction, would be able 

 to develop so delicate a structure " as the true perlitic. 



The Natunvissenschajtliche Wochenschrift of November 17 

 contains a summary of some of the most important preliminary 

 results of forty-seven balloon ascents made in Germany between 

 June 1888 and February 1895, compiled from communications 

 by Dr. R. Assmann in various scientific journals. In four of 

 the ascents the balloons contained self-recording apparatus only, 

 and of the other forty-three cases, M. Berson, an assistant in 

 the Meteorological Office at Berlin, made thirty-six ascents (in 

 four of which he was quite alone), and Lieut. Gross made 

 twenty-eight ascents. The heights attained in some of the 

 voyages were the greatest yet recorded. It was found : ( i ) That 

 the air-temperature above 4000 metres was considerably lower 

 than had been theoretically assumed, or deduced from earlier 

 ascents. This apparently points to the fact that in the earlier 

 ascents the thermometers were affected by solar radiation, while 

 in the recent ascents this defect was obviated by the use of the 

 aspirator invented by Dr. Assmann. (2) That the assumption 

 that the decrease of temperature with height was 'most rapid in 

 the lower strata of air, is untenable ; the decrease was found to 

 be fairly uniform with increasing altitude, and the isotherm of 

 32° F. was found to lie between 3600 and 3800 metres. 

 (3) That the stratum between 2000 and 4000 metres was rela- 

 tively too warm, owing to the greater condensation of clouds in 

 those regions. (4) That the seasonal variation of temperature 

 was very small above the height of 6000 metres. (5) That the 

 inversion of temperature during winter, and at night time, up to 

 the height of 1000 metres, appeared to be a regular phenomenon. 

 (6) That cumulus clouds were at times found at unexpected 

 altitudes. (7) That the surface of a massive layer of cloud 

 affected higher strata of air thermically and electrically, like the 

 surface of the earth. (8) That the electrical potential decreased 

 with height, pointing to the earth as the sole source of 

 atmospheric electricity. (9) That the aqueous vapour was 

 unexpectedly small in even moderately high regions of the air, 

 the variation in amount between two layers of cloud being often 

 very great. The balloon ascents have been temporarily dis- 

 continued, with a view to discussing the existing materials. 



The Cryptogamic journal Grevillea, which has been published 

 at irregular intervals since Dr. M. C. Cooke resigned the editor- 

 ship, will not appear again. The papers which were intended 

 for it have been transferred to W\& Journal of Botaiiy, still under 

 the editorship of Mr. James Britten. This journal will be pub- 

 lished monthly as heretofore, but will be increased in size from 

 thirty-two to forty-eight pages. 



The Report of the Department of Botany at the British 

 Museum for 1894, by Mr. W. Carruthers, shows that many 

 interesting additions were made to the Herbarium during the 

 year, one of the most important being the collection of fresh- 

 water Algse made by the late Dr. A. H. Hassall, which includes 

 a number of type specimens. Collections of flowering and 

 flowerless plants have also been obtained, by donation, exchange, 

 or purchase, from all parts of the world, especially from British 

 India and from our other colonies. 



Mr. F. N. Williams has issued a provisional and tentative 



list of the orders and families of British flowering plants, founded 



on the system Of classification of certain continental botanists. 



He pk^Joses to divide Phanerogamia into three " phyla," Angio- 



NO. 1363 VOL. 53] 



spermse, Anthospermse, and Gymnospermse, the second of these 

 consisting of one family only, the Loranthacese. The Angio- 

 spermae are again divided into two classes, the Dicotyledones 

 and Monocotyledones ; the Dicotyledones consist of two sub- 

 classes, the Sympetalse (Tetracyclicae and Isocyclicse) and the 

 Choripetalae (Eucyclicse, Phalangiata, Aphanocyclicae, Calyci- 

 florse, Centrospermae, and Archichlamydese). The whole range 

 of flowering plants is further grouped under 42 orders and lio 

 families. 



Appendix II. of the Bulletin oj Miscellaneous Information 

 of the Royal Gardens, Kew, is devoted to a list of the New 

 Garden Plants of the year 1894. It includes not only plants 

 brought into cultivation for the first time during the year, but 

 also the most noteworthy of those which have been reintroduced 

 after having been lost from cultivation, and some which had not 

 previously been properly described. In addition to species and 

 botanical varieties, all hybrids, whether introduced or of 

 garden origin, but described for the first time in 1894, are 

 included. The number of hybrids is especially noteworthy in 

 Cypripediu7n and other genera of Orchidea. The total number 

 of names in the list is about 500. 



An absolutely black body is one which both radiates and com- 

 pletely absorbs radiations of any wave-length. It is practically 

 impossible to prepare such a body by artificial blackening ; but 

 Messrs. W. Wien and O. Lummer have invented a body which 

 answers all requirements in the way of perfect blackness. This 

 quality is impaired by reflection of any kind from the surface, 

 and hence the inventors take care that the body in question shall 

 be supplied with exactly those kinds of radiation which it re- 

 flects, and which its radiation lacks in consequence. The in- 

 terior of a hollow sphere at any uniform temperature is in a 

 perfect condition in this respect, since there is perfect equilibr ium 

 between the heat received and given out. By making an open- 

 ing at one point, this state is only slightly disturbed, and the in- 

 side of the hollow sphere will act as a perfectly black body. 

 From a disquisition which appears in Wiedematm^s Annalen, it 

 appears that the authors propose to use this body and a bolometer 

 to test Boltzmann's law, which makes the radiation proportional 

 to the fourth power of the absolute temperature. 



Industries and Iron has commenced the issue of a series of 

 portraits of eminent workers in the field of engineering science. 

 Two portraits have already appeared as supplements to our 

 contemporary— one of Lord Armstrong, in the issue of November 

 29, and the second, of Sir Douglas Fox, in the issue of 

 December 6. 



The December number of Science Progress contains an ac- 

 count, by Dr. D. H. Scott, F.R.S., of the late Prof. William- 

 son's researches on the carboniferous flora. Other papers in- 

 cluded in the number are on mineral transformations, by Mr. 

 H. A. Miers ; some applications of the theory of osmotic 

 pressures to physiological problems, by Dr. E, Starling ; theories 

 of electrolysis, by Mr. C. Dampier Whetham ; recent papers 

 treating of the Upper Paleozoic beds, by Mr. Marr ; and a 

 notice of the discoveries and researches of the great physiol- 

 ogist, Carl Ludwig, by Dr. Leon Asher. 



Some of our readers may be interested in an ingenious puzzle 

 which has been devised by Mr. W. Radcliffe. It consists of 

 three sets of discs of equal sizes, each set containing the seven 

 principal colours of the spectrum ; and the problem is to arrange 

 nineteen of these so that there will be seven groups of the same 

 size and shape, each group containing the seven different colours. 

 Notwithstanding that there are 5040 possible solutions to this 

 " seven-colour puzzle," the result is by no means easily attained. 

 It should furnish a useful exercise for young children in dis- 

 tinguishing colours. 



