July i, 1920] 



NATURE 



559 



The greater part of a skeleton of the giant extinct 

 marsupial Nototherium • has lately been found in 

 Mowbray Swamp, Tasmania. The skull and the limb- 

 bones of the left side are described as well preserved, 

 and are especially important for comparison with the 

 numerous scattered remains of the same animal dis- 

 covered in the Pleistocene deposits of Australia. The 

 skeleton of Nototherium is less satisfactorily known 

 than that of the allied Diprotodon, of which manv 

 specimens were found in Lake Callabonna, South 

 Australia, about twenty-five years ago. 



We have received a copy of vol. v. (1918-19) of the 

 Journal and Proceedings of the Royal Society of 

 Western Australia, from which we learn that this 

 society makes steady progress in membership and in 

 the value and importance of its publications. The 

 papers deal mainly with Western Australian problems. 

 Prof. W. G. Woolnough writes on the physiographic 

 elements of the Swan coastal plain, adding several 

 details that have been overlooked in more general 

 accounts. An important historical paper is one by 

 Mr. J. S. Battye on the early colonisation of Western 

 Australia. Mr. W. A. Saw contributes a paper on 

 town-planning in Australia. His paper is noticeable 

 for a number of well-chosen illustrations showing 

 good and bad planning in various Australian towns. 



M. Emile Belot, whose artificial volcanoes were 

 recently mentioned in Nature, vol. civ., p. 575, 

 has published a work on "L'Origine des formes 

 de la Tei re et des Plan^tes " (Paris : Gauthier- 

 Villars, price 14.40 francs). While holding that the 

 earth and the moon developed from a state of 

 luminous vapour of nebular origin, the heat of this 

 vapour not being due to mere contraction, he points 

 out, on the analogy of novae, that the intensely heated 

 stage may have lasted only a few months, while other 

 successive changes, such as those when rains of 

 chlorides fell upon a warm surface, may have 

 occurred during the first few years of terrestrial evolu- 

 tion. We cannot here quote the figures bv which 

 M. Belot argues that the first waters would condense 

 in the primitive atmosphere, owing to its high pres- 

 sure, at the temperature of 364° ; it is sufficient to 

 mention that, on similar numerical reasoning, he 

 shortens the interval between the first rainfall 

 (.Antarctic) and the middle- of the Carboniferous 

 period to less than ten million years. The tectonics 

 of the crust are discussed with the aid of simple but 

 suggestive diagrams, and the frequent reversal of 

 views now popular will certainly encourage thought. 



Among the handsome series of Professional Papers 

 issued by the U.S. Geological Survey in these years 

 of turmoil we may note one by Mr. E. de K. Leflfing- 

 well (No. 109) on "The Canning River Region, 

 Northern Alaska." Its description and illustrations 

 of soil and vegetation above permanently frozen 

 ground, or above a subsoil consisting almost entirely 

 of ice, are of wide interest in lands in which such 

 conditions once prevailed. The author uses the term 

 " ground ice " for bodies of ice in frozen ground, 

 which involves confusion with what has always been' 

 known as ground ice ("anchor ice" is preferred by 

 NO. 2644, VOL. 105] 



Mr. Leffingwell) in rivers or in shallow seas. In 

 most of the areas in which underground ice has been 

 recorded, the downward limit of seasonal thawing is 

 less than 7 ft., 3 ft. being the rule. The author 

 shows, however, that this ice is a product of surface- 

 thawing, water penetrating downwards and adding 

 to the frozen masses at the present day. Underground 

 ice will form wherever the mean annual temperature 

 is some 4°-6° C. below freezing point. The author 

 makes a strong case for his view that very large 

 continuous ice-masses, with occasional inclusions of 

 earth, like those of the New Siberian Islands, may 

 arise from the growth year after year of ice-wedges 

 originating from surface-cracks. 



On May 27 Mr. B. S. Gossling read an interesting 

 paper on "The Development of Thermionic Valves 

 for Naval Uses " to the Institution of Electrical 

 Engineers. He gives first a history of the introduc- 

 tion of the thermionic valve into naval radio-tele- 

 graphy, laying stress on the use of Langmuir's 

 formulae for the value of the electron current as a 

 guide to the numerical design of valves. To old- 

 fashioned electricians the formulae, which are 

 numerous, are very uninviting. The physical dimen- 

 sions on both sides of the equations appear to be 

 quite different, and the continual introduction of the 

 voltage to the power 1-5 is very puzzling. We think 

 that the time has now come when the definitions of 

 the fundamental quantities should be made more 

 rigorous, and symbols should be used for the various 

 quantities which show their physical dimensions. In 

 the paper the successive stages of the approximations 

 which were adopted in the calculation of the charac- 

 teristics of valves are recorded. The final result shows 

 that the observed behaviour of a high vacuum valve 

 can to a first rough approximation be accounted for 

 in terms of known physical laws. Many ingenious 

 tests are described. The method adopted, for instance, 

 for estimating the vacuum in a valve while still on 

 the pump is to have a special vacuum tube attached 

 to the apparatus and measure the width of the 

 "cathode dark space." The paper gives a good idea 

 of the immense amount of work done on the valve by 

 physicists and engineers during the war. The varia- 

 tions of the thermionic properties of the valves which 

 were so puzzling and annoying a few years ago have 

 now been brought within bounds, and a rough 

 standard specification for their production is given. 

 Unfortunately, sufficient information to enable rigid 

 life test clauses to be made is not yet available. It 

 is a great step forward, however, that even a rough 

 specification can be given. 



Bulletin No. 2 for 1920 of the Classe des Sciences 

 of the Royal Academy of Belgium contains a com- 

 munication from Messrs. J. E. Verschaffelt and R. 

 Crombez on the anomalous dispersion of methyl-violet, 

 fuchsine, and paranitrosodimethy'aniline. The authors 

 use the method of Soret, which Wood also adopted, which 

 depends on the division of a glass trough with parallel 

 surfaces into two parts by a glass partition extending 

 from one corner to the opposite one. One of the 

 prismatic troughs thus formed is filled with a solution 

 of the material the dispersion of which is to be inves- 



