40 



NATURE 



[May I: 



is only about half that of antimony-bismuth, but the gain in 

 sensitiveness, due to lessened thermal capacity, quite out- 

 measures this defect. Prof. Rubens has succeeded in making 

 such a thermo-pile with twenty couples in a line of 20 mm. ; 

 the resistance is 3-5 ohms, and the E.M.F. o-ooio6 of a volt 

 per i" C. This must be regarded as a very great advance in 

 radiometry. It would be interesting to compare this instrument 

 with photo-electric cells as regards their respective power of 

 measuring stellar radiations. It should be noted that this is not 

 the first time an iron-constantan couple has been applied to 

 thermal investigations. 



"The collapse of a spherical shell under pressure" is a 

 problem which has long puzzled the minds of mathematicians, 

 and one which both engineers and geologists would be glad to 

 see solved. Ah interesting series of experiments in which a 

 hollow hemisphere of metal was made to collapse by the pres- 

 sure applied on top of it by another hemisphere or plane, is 

 described by Prof. H. Schoentjes, of Ghent, in the current 

 Bulletin de VAcadhnie royale de Belgiqtie (1898, No. 3). Prof. 

 Schoentjes gives excellent photographs showing various cases 

 of collapse in segments ; triangular, quadrangular, pentagonal 

 and hexagonal forms being all represented. The present paper 

 forms the sequel to one published in 1890, and among the 

 author's conclusions the following are noteworthy : — When two 

 similar hemispheres of 10 cm. diameter were crushed together 

 by a hydraulic press with their summits in contact, only one of 

 the hemispheres collapsed ; the cavity formed was spherical, and 

 was moulded on the undeformed hemisphere just as if the latter 

 hemisphere were solid. When a hemisphere of 15 cm. diameter 

 was crushed against one of 10 cm , the smaller one penetrated 

 nine times out of ten into the larger one ; the cavity was at first 

 spherical, but afterwards its margin became polygonal. In one 

 case only (and the author could not succeed in repeating the 

 experiment), both hemispheres were deformed ; the larger one 

 first penetrated the smaller, but under a force of 80 kilogrammes 

 the edge of the cavity began to penetrate the large hemisphere. 

 When a hemisphere was crushed by a plane the normal 

 deformation was found to be hexagonal. 



The mathematical theory of the propagation of earthquake 

 shocks is the subject of a somewhat interesting investigation at 

 the hands of M. P. Rudski, an abstract of whose papers has 

 just reached us {Anzeiger der Akademie der Wissenschaflen in 

 Krakati, November 1897). The author examines the consequences 

 of the assumption made by Prof A. Schmidt, of Stuttgart, 

 that the wave-velocity in the interior of the earth is a function 

 of the radius vector, which decreases as the latter increases. 

 Under such circumstances, the rate of propagation of earth- 

 quakes along the earth's surface decreases from the epicentre 

 outwards till a certain circle is reached, and then increases up 

 to the antipodes of the epicentre. The position of the bound- 

 ing circle in question depends on the depth of the disturbance, 

 and M. Rudski considers it possible, from observations of 

 earthquakes, to determine the relation between the wave- 

 velocity and the radius vector. 



A SERIES of observations of the temperature of the soil at the 

 observatory of Catania from 1 892 to 1 896 has been published by 

 Dr. Emmanuele Tringali in the Atti dell 'Accademia Gioenia di 

 Scienze Naturali. In addition to confirming the well-known 

 laws according to which the diurnal and annual variations of 

 temperature decrease and undergo retardation with increasing 

 depth. Dr. Tringali finds that at Catania the velocity of trans- 

 mission of the diurnal fluctuations is about 20 cm. for every ^\ 

 hours, and that these fluctuations become practically unim- 

 portant at a depth of 60 cm. , where they onlyamount to a few 

 tenths of a degree when the atmospheric temperature changes 

 as much as 17°. 



NO. 1489, VOL. 58] 



The summary of the Weekly Weather Report for the first 

 quarter of this year, recently issued by the Meteorological 

 Council, shows that in all the principal wheat-producing dis- 

 tricts, except the north of Scotland, there is a considerable 

 deficiency in the amount of the rainfail ; while in the grazing, 

 &c., districts a deficiency is everywhere shown. Looking at 

 the values for the winter half-year, the excess in the north of 

 Scotland is 3*5 inches ; this is, of course, due to the tracks taken 

 by the areas of low barometric pressure. The greatest deficiency 

 occurs in the south of England and Channel Islands, where it 

 amounts to 7 inches, and it exceeds 5 inches in the midland 

 parts of England. As these values are for large districts, of 

 course at some individual stations the deficiency is much more 

 marked. 



We drew attention last week to the important meteorological 

 station established by the Corporation of Southport, and we are 

 glad to learn that the municipal authorities at many other 

 stations are not behind that place in recognising the value of 

 accurate meteorological observations, and of placing the stations 

 in connection with the Meteorological Office or the Royal 

 Meteorological Society. Among these we may specially mention 

 the station established by the Corporation of Eastbourne, under 

 the superintendence of Mr. R. Sheward, who has for many 

 years published reports of the observations at that favourite 

 sea-side resort, where every care has been taken to place the 

 instruments in the best possible positions. Eastbourne enjoys a 

 large amount of bright sunshine, the average annual duration 

 being 17 19 hours, while for London the average is only 1240 

 hours. Mr. Sheward bears witness to the value of the storm- 

 warning telegrams issued by the Meteorological Office. He 

 states that since the establishment of storm signals there, in 

 1893, no mishap has occurred to the fishing fleet, although his 

 tables show that some serious gales have been experienced. 



The Bureau of Agriculture and Immigration of the State of 

 Louisiana has recently issued the first volume of a treatise on the 

 history, botany, and agriculture of the sugar-cane, and the 

 chemistry and manufacture of its juices into sugar and other 

 products, by Prof. W. C. Stubbs, Director of the Audubon 

 Park Experimental Station at New Orleans. One chapter is de- 

 voted to the botanical relations of the plant, one to its anatomy 

 and physiology, one to its modes of reproduction, and one to 

 bacteriological notes on red cane. 



The plant yielding what is known in commerce as Ceara 

 rubber or Mani9oba, and shipped from the Brazilian ports of 

 Ceara, Bahia and Pernambuco, was identified at Kew eleven 

 years ago as Manihot Glaziovii, Muell. Arg. Specimens of the 

 plant were sent from Kew to our Colonies and possessions 

 which seemed suitable for its cultivation, and the results of the 

 attempts to introduce the Ceara rubber tree are described in the 

 latest issues of the Kew Bulletin (Nos. 133-134, 1898). The 

 following is a summary of the information thus obtained, and it 

 furnishes another example of the valuable work done by Kew in 

 the endeavour to increase the natural resources of British pos- 

 sessions : (i) The plant is readily propagated both from seeds 

 and cuttings. Seeds are abundantly produced in almost every 

 part of the world where the plant has been introduced. They 

 may be gathered from plants when only three to five years old. 

 There is therefore the great advantage that a large area could be 

 planted within a comparatively short period. Sowing the seeds 

 in the position where they are to grow permanently is universally 

 adopted in Brazil. It is possible, if adopted elsewhere, this 

 plan would greatly reduce the cost of establishing plantations. 

 (2) The Ceara rubber plant is very hardy, a fast grower, free 

 from insect and fungoid attacks, requires little or no attention 

 when once established, and thrives in poor, dry and rocky soils 

 unsuited to almost any other crop. It is evident, however. 



