February 24, 19 16] 



NATURE 



715 



Kidini:^ to devise regulations for the substitution of 

 li ire-cake for sulphuric acid in various processes of 

 he woollen trades, and to arrange for the best centres 

 11 which the Government Explosives Department can 

 send quantities of nitre-cake for the convenience of 

 local users. The greatest difficulty lies in carting and 

 transport. It is pointed out that the shortage of acid- 

 seriously affected the wire trade of some districts, 

 and that the Government, although taking action 

 with regard to the textile trades, has apparently not 

 yet realised how seriously the wire trade is affected 

 by the shortage of acid. 



The final general memorandum on the indigo crop 

 of 1915-16, based uix)n reports received from provinces 

 containing practically the whole area under indigo in 

 British India, has been issued by the Department of 

 Statistics, India, and forms the subject of a short 

 article in the Chemical Trade Journal of January 29. 

 The total area (314,300 acres) is 112 per cent, in 

 excess of the finally revised value of last year (148,400 

 acres). The total yield of dye is estimated at 

 39,900 cwt., as against 25,200 cwt., or an increase 

 of 58 per cent. The average output per acre works 

 lit at 14 lb., as against 19 lb. in the preceding year. 

 The increase in area is due to high prices of indigo 

 due to the war, which range from 12s. to 13s. a lb., 

 as LX)mpared with 2.v. Sd. in 19 13. The season on 

 the whole has not been favourable to the crop, except 

 in Madras. In some places poor crops were obtained 

 owing to a scarcity of trustworthy seed at the sowing 

 lime. Data are given showing the quantities of 

 natural and synthetic indigo imported into the United 

 Kingdom in the last five years. 



A PAPER on turbo blowers and compressors was 

 read recently before the South Wales Institute of 

 Engineers, and is reprinted in Engineering for 

 February 11. The authors, Mr. H. L. Guy and Lieut. 

 F. L. Jones, give very full details and methods of 

 design for both classes of machines. There is also an 

 appendix on the measurement of large quantities of 

 air, and the authors state that the most convenient 

 and accurate method consists in discharging it into 

 the free atmosphere through a standard convergent 

 nozzle. A drawing of this nozzle is given. Care must 

 bo taken that the air approaches the nozzle in a steady, 

 uniform stream. It is only necessary to measure the 

 temperature and pressure before and after the nozzle 

 in order to be able to calculate the volume of air pass- 

 ing through it. The coefficient of discharge has been 

 measured for the author's .standard nozzle and has 

 been found to be between 10 and 0-99. 



Messrs. Dulau and Co., Ltd., will publish almost 

 immediately a translation of Thonner's "The Flower- 

 ing Plants of Africa : an Analytical Key to the Genera 

 of African Phanerogams." The work, which has 

 been revised and brought up to date, will contain 

 150 plates. 



The Cambridge University Press has undertaken 

 the publication in this country of two new American 

 medical journals, viz.. The Journal of Cancer Re- 

 search and The Journal of Immunology. The first- 

 named periodical (which will be issued quarterly) will 

 be the official organ of the American Association for 



NO. 2417, VOL. 96] 



Cancer Research, and contain contributions dealing 

 with statistics, immunology, pathology, and inherit- 

 ance. The second journal will be a bi-monthly, and 

 represent the American Association of Immunologists 

 and the New York Society of Serology and Hemato- 

 logy. 



The following monographs are in preparation for 

 publication by the Ray Society : — The British Centi- 

 |)edes and Millepedes, by W. M. Webb; The British 

 Earthworms, by the Rev. H. Friend; The British 

 I Hydrachnidae, by C. D. Soar and W. Williamson ; 

 The British Ixodoidea, by W. F. Cooper and L. E. 

 Robinson; and The Earwigs of the World, by Dr. M. 

 Burr. The three following works are in (•our<( of 

 publication : — The British Desmidlacea;, li\ W . and 

 Prof. G. S. West ; The British Freshwater Rhizopoda 

 and Heliozoa, by the late J. Cash and G. H. Wailes ;. 

 and The British Marine Annelids, by Prof. W. C. 

 Mcintosh. 



OUR ASTRONOMICAL COLUMN. 



Perrine's Comet (1896 VI 1.). — This periodic comet 

 is due to return to perihelion about the middle of 

 April. Search ephemerides have been calculated by 

 Dr. G. Stracke from orbital elements obtained from 

 observations made during Its 1909 apparition for three 

 assumed dates of perihelion passage, namely, April 

 75, 15-5, and 235, and are given in Circular No. 500 

 of the Astronoinische Nachrichten. The comet is ap- 

 parently close to the sun on the opposite side from 

 the earth, and at perihelion will be 200 million miles 

 from the latter. 



Comparison of Pendulums. — The method of coin- 

 cidences enables the rates of pendulums to be com- 

 pared with considerable accuracy even without acces- 

 sory apparatus. Using the " flash-box " — an optical 

 device that enables the moment of coincidence to be 

 determined with greater precision — estimations of one- 

 thousandth of a second are usually made in gravity 

 work. Seven significant figures are obtained in the 

 deduced times of oscillation of "half-seconds" pen- 

 dulums. An even higher order of accuracy is claimed 

 for an electro-acoustical method tried by M. A. Perot 

 {Comptes rendus, clxil.. No. 5), that Is stated to render 

 sensible periods less than 1/250,000 of a second. The 

 arrangement employed consists of a battery and con- 

 denser shunted through very high resistance, connected 

 in parallel to two open circuits, including telephones. 

 Contacts made by the pendulums under comparison 

 make the circuits, and equality of the sounds given by 

 the two telephones indicates coincidence. 



The Variation of Latitude. — Prof. Kiyofusa 

 Sotome, who for a number of years had charge ot the 

 latitude observations at Tokyo, suggests an explana- 

 tion of the Kiniura "c," also embracing the lesser- 

 known term given by the chain-method of reduction, 

 namely, the '"closing sum." Both together are held 

 to be a measure of the " Imperfection " of the spirit- 

 level. In the course of evaluating the micrometer 

 screw by high-latitude stars, it was found that whether 

 the zenith telescope was in the east or west position 

 the bubbles of the pair of attached levels showed a 

 southerly creep about four times greater In winter 

 than In summer. For this two causes are found to be 

 about equally operative ; one resides in the spirit-levels 

 and is independent of a regular northward tilt of the 

 telescope that accounts for the other half. The vary- 

 ing inclination of the telescope is due to differential 

 changes in the stand and also to a periodic diurnal 



