152 



NATURE 



[March 31, 192 1 



been carefully scrutinised and graded according to 

 their completeness, accuracy, and the freshness of 

 the material analysed. They are divided into four 

 parts :—(i) Superior analyses of fresh rocks; (2) in- 

 complete analyses of fresh rocks ; (3) superior analyses 

 of altered rocks and tuffs; and (4) inferior analyses. 

 Part I, including 4980 analyses, constitutes the most 

 complete statement yet published of the distribution 

 of rocks in the subdivisions of the quantitative classi- 

 fication of igneous rocks of Qross, Iddings, Pirsson,and 

 Washington (1903), an explanation of which is given 

 in appendix i. The analyses in the other three parts 

 are arranged under their published rock-names. A 

 valuable feature of the arrangement is the geo- 

 graphical grouping of analyses in each subdivision ; 

 this brings out the extreme scarcity of trustworthy 

 analyses of rocks of some of the most important 

 petrological areas. In this connection it may be noted 

 that for rocks of the British Isles there are only 

 264 analyses recorded in the whole book, distributed 

 as follows: 77 in part i, 9 in part 2, 90 in part 3, 

 and 88 "inferior" analyses in part 4. Dr. Washing- 

 ton's work will be of inestimable value. The com- 

 plete record of analyses here presented and their 

 arrangement by the quantitative system will facilitate 

 the reviewing of our current nomenclature in the light 

 of the chemical composition of rocks. 



Dr. C. E. Adams, Government Astronomer and 

 Seismologist in New Zealand^ and Prof. E. Marsden 

 have recently visited the geophysical observatory at 

 Apia founded in 1902 by the Society of Sciences of 

 Gottingen. Their report appears in the New Zealand 

 journal of Science and Technology (vol. iii., 1920, 

 pp. 157-61). The observatory is the most complete of 

 its kind in the Pacific. The magnetic department 

 provides for the continuous registration of the hori- 

 zontal component, the vertical component, and the 

 declination. The seismological observatory contains 

 Wiechert seismographs for both horizontal and vertical 

 components of the motion. A recording tide-gauge 

 is maintained in the adjoining harbour. In addition 

 to the usual astronomical and meteorological observa- 

 tions, arrangements have been made for the inves- 

 tigation of the upper atmosphere by means of hand- 

 hauled kites and free balloons. New Zealand having 

 accepted the inandate over Samoa, the authors urge 

 the desirability, with which all will agree, of main- 

 taining the observatory, which is well-equipped and 

 situated, at its full pre-war efficiency. 



One of the most serious difficulties with which 

 inventors of apparatus for use on aeroplanes during 

 the war had to contend was the absence of any 

 information as to the special circumstances in 

 which the apparatus had to operate and the arrange- 

 ments which had been made to enable it to function 

 properly in those circumstances. Even now it is 

 not easy for an inventor not engaged in aeroplane 

 construction or design to get to know what apparatus 

 is actually used and in what respects it falls short of 

 the requirements of the service. To all who are 

 interested in the subject an article on aeronautical 

 instruments in the January issue of the Journal of 

 the FrankRn Institute by Prof. C. E. Mendenhall will 



NO. 2683, VOL. 107] 



be welcome. It divides them into four groups con- 

 cerned respectively with the engine, the aeroplane, 

 navigation, and military purposes, and in each group 

 the instruments used and the special difficulties with 

 which they have to contend are described. The 

 article is well illustrated, and gives much valuable 

 information in a compact and readable form. 



The " British Meteorological and Magnetic Year 

 Book," 1917, part 4, has recently been published by 

 the Meteorological Office. It comprises hourly read- 

 ings of terrestrial magnetism at Eskdalemuir Ob- 

 servatory and summaries of the results obtained in 

 terrestrial magnetism, meteorology, and atmospheric 

 electricity, chiefly from self-recorling instruments at 

 the observatories of the Meteorological Office. The 

 work consists mainly of tabular matter. The mean 

 daily variation of the various meteorological elements 

 is given for each month and for the year for the five 

 observatories, Aberdeen, Eskdalemuir, Cahirciveen 

 (Valencia), Richmond (Kew), and Falmouth. C.G.S. 

 units are used for meteorological data, with tempera- 

 ture in absolute degrees. The normal constant for 

 absolute temperature given is 200°. With a normal 

 constant of 273° the resulting values would be in 

 ordinary degrees Centigrade, a system adopted by 

 many meteorologists on the Continent and by some 

 at home. To the uninitiated it gives a reading more 

 easily comprehended, although in the British Isles 

 very occasionally some of the values would be given 

 with the negative sign. For terrestrial magnetism 

 hourly observations are given for each month, with 

 notes of the special features of the disturbances ex- 

 perienced. Notes are given at the end of the volume 

 on the management of the magnetic and electrical 

 instruments and on results of interest, showing the 

 method of observation and the treatment in discussion. 



In two papers communicated to the Rumanian 

 Academy of Sciences for 1920, G. G. Longinescu with 

 G. P. Teodorescu and G. Chaborski respectively 

 describes modified methods for the separation of the 

 metals of the second group in qualitative analysis 

 and of hydrochloric acid in the presence of hydro- 

 bromic and hydriodic acids. In the first, ammonium 

 carbonate is used in the separation of the metals 

 of the sub-group instead of ammonium sulphide. 

 Caustic soda is used in the separation of the 

 remaining metals. The separation of a bromide from 

 the mixture with a chloride and iodide is effected by 

 heating with alcohol and sulphuric acid. Hydro- 

 chloric acid is evolved, the hydrobromic acid decom- 

 poses into bromine which forms ethylene bromide, 

 and the iodine remains principally in the liquid. 



The economics of ship propulsion are dealt with in 

 a paper entitled "Coal, Oil, or W'ind," read on 

 December 14 before the Institution of Engineers and 

 Shipbuilders in Scotland by Mr. C. O. Liljegren. So 

 far as ships are concerned, wind only can be used' 16 

 save fuel. Properly applied, this method of propul- 

 sion would mean an enormous saving in fuel and a 

 reduction in the cost of carrying both passengers and 

 freight. Sailing ships can be run at less cost per ton- 

 year than any machine-driven vessel, whatever the 

 price of fuel. The author has studied Sauerbeck's 



