April 



[919] 



NATURE 



91 



limited by climatic conditions; there is also the ques- 

 tion as to the economic production of inoculating 

 material in quantity, 



A SEVERE earthquake was felt over eastern Bengal 

 .nd Assam, most of Burma, and in north-east India 

 1- far west as Lahore on July 8, 1918. Capt. Murray 

 ^tuart, who has investigated the earthquake on behalf 

 of the Geological Survey of India, has published an 

 interestmg summary of his results (Records Geol 

 Surv. India, vol. xlix., 1918, pp. 173-89). Without 

 )relimmary warning, the earthquake occurred at about 

 ;.5o p.m. (Indian standard time), at a time when 

 nost people were out of doors, so that the loss of 

 .fe was exceedingly small. The epicentral area lies 

 M)me hundred miles to the south-east of that of the 

 ^reat Assam earthquake of 1897, the centre of this 

 .rea being in the Balisera Hills, about 3^ miles south 

 -f the railway at Srimangal. Nearly all brick build- 

 ngs were destroyed in the area of greatest intensity, 

 ut no fault-scarps were formed, though there was 

 much shifting and fissuring of the surface material 

 and ejection of water and sand. Making use of 

 Dutton's well-known method, Capt. Stuart estimates 

 hat the focus was at a depth of eight or nine miles. 



In an article on the progressive desiccation of Africa 

 n the South African Journal of Science (vol. xv.. 

 No. 3) Mr. E. H, L. Schwarz discusses at length the 



arious hydrographical systems of that continent. 



ertain engineering works are proposed which the 

 luthor believes would have a beneficial effect on 

 South Africa. One is a dam across the Cunene River 

 below Kinga, in Angola, some 250 miles from the 

 coast; the other is a dam across the Selinda River or 

 the Chobe River a few miles above its confluence 

 with the Zambesi. These weirs would restore to 

 Lake Ngami its old area, fill up the Etosha pan, and 

 inundate much of the Makarikari depression. This, 

 Mr. Schwarz believes, would result in a greater 

 i:[eneral humidity which would have the effect of 

 bringing rain to the Kalahari desert; otherwise he 

 foresees desert conditions gradually spreading through 

 South Africa. Possibly Mr. Schwarz takes an unduly 

 pessimistic view of the future of the country, and 

 all authorities do not agree with him in his con- 

 tention that the agricultural conditions in the Karroo 

 have changed for the worse within recent times. It 

 is open to argument whether the creation of such 

 an immense inland lake would have ihe desired effect 

 in modifying the climate, even if the scheme were 

 practicable, but the paper is valuable for the facts 

 it contains and the important issues which it raises. 



A QUANTITATIVE examination of the relation of rain- 

 fall, to configuration in certain localities of the British 

 Tsles has been made by Mr. Carle Salter, and was 

 the subject of a lecture to the Institution of Water 

 Engineers. The paper is now published by the institu- 

 tion as a separate pamphlet. Rainfall may be 

 classed as convectional, cyclonic, or orographical. The 

 first two types are only slightly affected by con- 

 figuration of the land, but an examination of a rain- 

 fall map of the British Isles shows that orographical 

 rains predominate in the course of the year. In 

 winter orographical rains are most frequent, and in 

 'iummer their influence, while apparent, is not so well 

 marked. Unfortunately, no records exist of the 

 average amount of rain which falls annually over 

 the sea in the neighbourhood of the British Isles. 

 Records of this nature, if available, would give a 

 measure of the amount of non-orographical rain 

 which falls over the land generally. -An examination 

 of data from stations near sea-level shows that eleva- 

 tions of only a few feet affect the amount of rainfall. 



NO. 2579, VOL. 103] 



The rate of increase per 100 ft. of altitude varies 

 within wide limits. It is lower on slopes parallel 

 to the prevailing winds than on slopes at right angles. 

 On fairly steep ridf?es close to the sea the maximum 

 rainfall often occurs slightly on the leeward side of 

 the crest. These and other cases Mr. Salter dis- 

 cusses at length with a wealth of illustration from 

 the records of the British Rainfall Organisation. It 

 is unnecessary to point out the great importance of 

 researches of this nature in relation to problems of 

 water-supply. 



The evidence of cohiplete combustion of coal is to 

 be sought in the flue-gases. According to the Coal 

 Age for November 21 last, these gases, when the com- 

 bustion of the coal is complete, consist in part of 

 carbon dioxide, of which there should be not less than 

 16 per cent. When the flue-gases show by analysis 

 less than that percentage, too much air has been 

 allovyed to pass through the furnace. Even if we 

 admit one-thir<l more air into the fire-box than is 

 theoretically nece>,sary for complete combustion, the 

 escaping gases should contain from 20 to 22 per cent, 

 of carbon dioxide. In practice every pound of coal 

 burned requires for its complete combustion 200 cu. ft. 

 of air. When burned under such conditions, a pound 

 of coal should develop 13,000 B.Th.U. 



In a paper read to the Institution of Electrical 

 Engineers on February 27 Drs. Barclay and Smith 

 discussed the determination of the eflficiencv of the 

 turbo-alternator. The American Institution of Elec- 

 trical Engineers gives a conventional theoretical 

 method of computing the losses, but it is known in 

 certain cases to lead to very erroneous results. The 

 authors have found out, by experiments carried out 

 at Messrs. Vickers's works,' that the alternator losses 

 can be determined conveniently and accurately under 

 actual load conditions by measuring the amount of 

 heating undergone by the air used for ventilating the 

 alternator to keep it cool. The method is practically 

 the same as that described by Sir Richard Threlfal'l 

 to the institution in 1903. The main improvements 

 lie in the methods of measuring the quantity and 

 temperature of the air. In the discussion we' were 

 surprised to hear that the " stray losses " — that is, the 

 losses not taken into account in the usual conventional 

 way of testing— sometimes amounted to 40 per cent, of 

 the total losses. We should have thought that the 

 cause of this must be fairly self-evident. 



A COAL meter for boilers, made by the Lea Recorder 

 Co., Ltd., of Manchester, is described in the Engineer 

 for March 14. This meter is intended for boilers fitted 

 with chain-grates. The amount of fuel passing under 

 the fire-door depends upon the depth, i.e. the thickness 

 of the fire, and the velocity of the fire-grate, and both 

 these variables are taken into account by the 

 mechanism of the meter, which somewhat resembles 

 that of the well-known V-notch recorder for water 

 measurement made by the same firm. Tests have been 

 made at the works of Messrs. Browett and Lindley, 

 and are said to be satisfactory. The makers give a 

 guarantee of accuracy to within 5 per cent. 



\s illustrated article in Engineering for February 28 

 gives an account of submarines built for the British 

 Navy during the war by Messrs. Vickers. Fifty-four 

 boats in all were built and commissioned in a period 

 of fifty-one months ; of these the details of the K type 

 are specially interesting. These vessels have a sub- 

 merged displacement of 2570 tons, and are 339 ft. 

 long by 26 ft. 8 in. beam. The double-hull principle 

 is embodied in a modified form. The speed is twenty- 

 four knots on the surface, the power being obtained 

 from twin sets of geared steam turbines, which 



