6c o 



NATURE 



[January 30, 19 13 



Iniversity of Chicago. The trip was undertaken for 

 the purpose of making a scientific investigation of the 

 cvcads of the eastern hemisphere, and the principal 

 places visited included the Sandwich and Fiji Islands, 

 New Zealand, Australia, and South Africa. The 

 cvcads are a gymnosperm family, of which the 

 remote ancestors were abundant in the Palaeozoic age 

 and the less remote ancestors were abundant 

 and had a world-wide distribution in the Mesozoic. 

 Only nine genera now remain, confined to tropical 

 and subtropical regions, and even there are very local 

 in their distribution. Of the four western genera, one 

 ranges from Florida to Chile, two occur only in 

 Mexico, and one only in Cuba; of the five eastern 

 genera, one ranges from Japan to Australia, two are 

 found only in Australia, and two only in South Africa. 

 Prof. Chamberlain has during the last twelve years 

 made detailed studies on the American cycads, and 

 with the material now available intends to make a 

 similar study of the Oriental forms, which should 

 yield valuable results, especially since the Pateozoic 

 ancestors of the family are becoming well known 

 through the researches of various English pateo- 

 bolanists, and the Mesozoic forms are being cleared up 

 bv Prof. Wieland, of Yale University. 



The interbasaltic iron ores and bauxites of the 

 north-east of Ireland have long been objects of in- 

 terest and speculation to geologists and others. The 

 Geological Survey of Ireland is therefore to be con- 

 gratulated on the production of its latest memoir, 

 which is devoted entirely to these rocks. The new 

 memoir is a well-illustrated volume of 220 pages, 

 giving full details of these formations. Dr. Moss 

 contributes a chapter on the plant remains, and in 

 another chapter a large number of analyses have been 

 collected. Two good colour-printed maps, showing 

 the outcrops of the ores and clays and the associated 

 basalts and rhyolites, are enclosed in a pocket. In an 

 extremely interesting introductory chapter Prof. Cole 

 discusses the nature and origins of these beds and the 

 formation of laterite, bauxitic clays, and bauxitic iron 

 ores in general. The typical downward succession 

 within the interbasaltic beds in the county of Antrim 

 is (i) pisoUtic iron ore; (2) "pavement," a material 

 varying from a siliceous iron ore to a lithomarge, 

 with a false appearance of stratification, due to 

 coloured streaks connected with the decomposition of 

 residual blocks of basalt; (3) lithomarge, decomposed 

 basalt retaining the original joint-structure, and often 

 showing pseudomorphs after the felspars of the 

 ground-mass. This passes down into a basic lava of 

 the Lower Basaltic Series. The pale bauxites are 

 derived from the rhyolites of the interbasaltic epoch. 

 Some of this rock has been laterised in situ ; else- 

 where it has first been detrital. The main mass of 

 the laterites and lithomarges of north-east Ireland 

 are to be regarded as typical examples of soils and 

 subsoils, formed under conditions now prevalent in 

 regions of seasonal rains, near the equator. 



In Symons's Meteorological Magazine for January 



Dr. Mill gives an interesting account of the rainfall 



of the British Isles for the year 1912, prepared from 



a preliminary examination of part of the vast mass of 



NO. 2257, VOL. 90] 



data at his disposal. The following extracts may be 

 useful in supplementing the summary already given 

 in our columns (Nature, January 16, p. 555), compiled 

 from another source. The rainfall over the whole of the 

 country was in excess of the average, with the excep- 

 tion of very limited areas ; generally speaking, the 

 least excess lay round the coast. England and Wales 

 had an excess of 21 per cent., Scotland 7 per cent., 

 and Ireland 9 per cent. The wet months were 

 January to March (the latter having an excess of 63 

 per cent.), June ( + 81 per cent.) to August ( + 58 per 

 cent.), and December ( + 43 per cent.). Of the re- 

 maining months, April and September had only about 

 half the average. In England and Wales, April had 

 only about one-fifth of the average, and in the south 

 of England it was one of the driest months ever 

 known ; in Ireland September had only 23 per cent, 

 of the average. There were four axes of high fall, 

 exceeding 20 per cent, above the average, running 

 parallel to one another across the United Kingdom 

 from S.W. to N.E. The most important of these 

 occupied the centre of England from Cornwall to 

 Yorkshire, and reached the south coast also in Sussex. 

 Within this area there ivas a strip stretching from 

 Land's End to Norfolk where the rainfall was more 

 than 30, and at places as much as 40 per cent, in 

 excess of the average. For the British Isles gener- 

 ally the yearly excess was 14 per cent, above the 

 average. 



The Bulletin de la Sociiie d' Encouragement, cxvii., 

 3 (Paris, 1912), contains a short report on an in- 

 genious chemical balance devised by M. A. Collot, in 

 which the weights used in weighing are attached or 

 detached by pressing buttons, the whole operation of 

 weighing taking place after the case containing the 

 balance has been closed. The sensitiveness is main- 

 tained constant by keeping the total load constant and 

 removing the weights from the side on which the 

 scale-pan containing the object is situated. 



In a short paper in The Electrician for January 10 

 Dr. Eccles shows how the efficiency of transmission 

 from the sending to the receiving aerial in any system 

 of wireless telegraphy may be calculated. He applies 

 his method to the original plain aerial of Marconi, 

 the first tuned aerial of Lodge, the recent coupled 

 circuits of Marconi, and to_ an ideal system sending 

 out a continuous train of waves. He comes to the 

 important conclusion that the present systems of 

 coupled circuits actuated by sparks have efficiencies 

 of transmission about 90 per cent, of that which would 

 be obtained by the use of a continuous generator of 

 electric waves ; hence the introduction of such gene- 

 rators can only lead to a small increase of the 

 efficiency of transmission. 



In "The Space-time Manifold of Relativity" (Proc. 

 American Acad, of Arts and Sc, vol. xlviii.. No. ix, 

 1912), Profs. E. R. \\'ilson and G. N. Lewis 

 give a full and very interesting account of 

 their attempts to construct systematically a 

 peculiar kind of non-Euclidean geometry suit- 

 able for the representation of the fundamental parts of 

 the modern theory of relativity, along with its appli- 

 cations to mechanics and elcctromagnetism. Their 



