SH 



NATURE 



\ApHl z, 1879 



out "with tweezers. The lower part of the tube is drawn 

 out for connection with the mercury pump. The powders 

 used for experiment were carefully painted on the opposite 

 sides of pith or mica disks, only water or alcohol being 

 used. 



Disks coated on alternate sides with chromic oxide 

 and precipitated selenium move in one direction to the 

 naked flame of a candle, and in the other direction when a 

 water screen is interposed. With saffranin and hydrated 

 zinc oxide the instrument does not more at all when 

 exposed to the naked flame, but revolves when a water 

 screen is interposed. With thallic oxide and Magnus's 

 green platinum salt, the instrument moves strongly when 

 no screen is interposed, but is stopped with a water 

 screen. These results are all in confonnity with the 

 figures. 



A pith radiometer coated with precipitated selenium 

 and chromic oxide was exposed to the radiation from a 

 colourless gas flame from a Bunsen burner, coloured in- 

 tensely green by thallium. To the eye, by this light, the 

 chromic oxide looked nearly white, and the selenium black. 

 The rotation due to the repulsion of the chromic oxide was, 

 however, apparently as strong as when the non-luminous 

 flame was used. This experiment proves that certain 

 substances have an opposite absorptive action on rays of 

 dark heat to what they have on light, and that an optically 

 white body may be thermically black, and vice versd. In 

 this case, for instance, chromic oxide was optically green, 

 and thermically black, while scarlet selenium was thermi- 

 cally white and optically black. W. Crookes 



{To be continued) 



'METEOROLOGICAL ORGANISATIONS 



IN the Journal of the Royal Statistical Bureau of 

 Prussia for 1878, there is published a report on the 

 meteorological organisations of the chief countries of 

 Europe, Part I., by Dr. Gustav Hellmann, who is rapidly 

 coming to the front as a first-class meteorologist. In 

 addition to considerable mental capacity and much 

 enthusiasm for the science, Dr. Hellmann has, at the 

 instance, and with the assistance of the Prussian Minister 

 of Public Instruction, especially qualified himself for the 

 work by undertaking tours more or less prolonged, in the 

 countries the meteorological systems of which he reports 

 on. These in the Part before us are the various systems 

 in France, Great Britain, Belgium, and Holland. With 

 the aid of a renewed grant he sets out on a second tour, 

 this time through northern Europe, especially Russia, for 

 the purpose of presenting similar reports on the meteoro- 

 logy of these countries. This action on the part of the 

 Prussian Government has been taken, in view of a con- 

 templated reorganisation of its meteorological system, so 

 that when the time comes, the system may be established, 

 not at haphazard, but on a sure basis, founded on the 

 fullest knowledge of the requirements of the science, and 

 on the best means to be adopted for its healthy deve- 

 lopment. 



The Weather Telegraph systems of France, Great 

 Britain, Belgium, and Holland, are fully detailed, very 

 special attention being given to the weather warnings of 

 France, carried out for the benefit of agriculture and 

 horticulture. This system of weather warnings, which is 

 so peculiarly adapted to the wants of Germany, was, as 

 our readers are aware, the last gift to meteorology of the 

 great Leverrier, to whom, in its practical bearings, meteo- 

 rology stands so deeply indebted. 



As regards France, meteorology would appear to have 

 a most hopeful future before it, as evidenced by the 

 mental activity brought to bear on the science, the fertility 

 of resource in devising new methods and subjects of obser- 

 vation, the breadth of view shown in making the study of 

 weather and climate subserve great public interests, and 

 withal by the pecuniary assistance liberally and heartily 



given by Government and other bodies intrusted with the 

 public funds, to the observatories, societies, and asso- 

 ciations in various parts of France that are doing its 

 meteorological work. Among the more special work 

 France is doing may be noticed the application of the 

 electric thermometer to the observation of the tempera- 

 ture of the air at great heights and of the soil at great 

 depths ; the establishment of several stations in Paris 

 for the investigation of the chemistry and micrography 

 of the atmosphere in their relations to the health of the 

 city; and the establishment of high-level stations, which 

 has been done largely through assistance given from the 

 public purse. 



We note with the liveliest satisfaction the great in- 

 crease of meteorological stations over these four countries, 

 the introduction of instruments for continuous observa- 

 tions in regions where they were much required, and a 

 more adequate observation of the rainfall, particularly 

 in the British Isles, where about 2,100 rain-gauges are 

 at work, and in the river-basins of France, where the 

 rainfall is noted at i,iii stations. 



Forcible attention is directed to the fact that in some 

 cases the reduction of the observations and publication 

 of the results are not carried out, or carried out very 

 imperfectly, so that no little difficulty is experienced when 

 conducting climatological inquiries, in obtaining the data 

 from considerable portions of Western Europe. This 

 defect ought to be rectified without delay. 



Reference is made to international stations, or stations 

 at which observations are made for purposes of inter- 

 national meteorology. But on looking at the diverse 

 hours of observation adopted by the different European 

 systems, it is evident that the attempt recently made to 

 found an international meteorology must be regarded as 

 a failure, since the prime and most elementary condition 

 of uniformity as regards hours of observation has been 

 neglected, the just views on this vital point propounded 

 by Humboldt and the meteorologists of his time being at 

 present, if appreciated, entirely set aside. 



MYCOLOGV^ 



IT is perhaps not generally known how very numerous 

 are the specimens comprised under the branch 

 Mycology, The mycological herbarium which is in the 

 course of transmission to Kew consists of at least 10,000 

 species, of which 7,500, comprising the Hymenomycetes 

 and Ascomycetes, have already been forwarded. But 

 not only are many species very beautiful in form and 

 colour, but the subject is one of great interest both in a 

 physiological and economical point of view, apart from 

 mere distinction of species and nomenclature, and, there- 

 fore, while especial journals are devoted to entomology, 

 malacology, algology, and other branches of natural his- 

 tory, it is quite right that we should have one devoted to 

 fungi. M. Roumeguere ought, however, to have inen- 

 tioned that England already possesses one in GreviUea 

 quite equal to the French journal, which has appeared 

 with great regularity ever since 1872, and is monthly 

 instead of trimestrial, of the existence of which he could 

 scarcely be ignorant, as it is referred to more than once 

 in the number before us. 



The Journal before us commences with a paper 

 on the much-vexed question of the real nature of 

 lichens, in which the author is altogether opposed 

 to Schwendener's theory of their parasitic growth on 

 Algse, There are two points which ought to be noticed : 

 that the growth of Gonidia from Hyphae was observed 

 by Mr, Berkeley, as recorded in the "Introduction to 

 Cryptogamic Botany," 2 while the stem of the curious 



' I "Revue Mycologlque : Recuell trimestrlel consacreU'fitudedes Cham- 

 pignons." Par M. C. Roumeguere. (Pans : J. B. BailUere et FJs.) . 



2 "Int. Crypt. Bot.," p. 373, Fig. 78(1 



3 "Int. Crypt. Bot.," p. 34'. Fig- 7^- 



