June 26, 1919] 



NATURE 



7>l^ 



both in the shape of food and in that of raw material 

 for industry. It has been argued that crops with a 

 higher starch-content can be grown more cheaply in 

 tropical countries, and the resulting alcohol could, 

 and would, be imported here. Against this Dr. Reilly 

 remarks truly that it is unwise for a country to rely 

 solely on foreign supplies. 



Among forthcoming books of science we notice the 

 following : — Vo'. iii. of the English translation, bv 

 H. Spencer-Browne, of Doyen's "Surgical Thera- 

 peutics and Operative Technique " (Bailliere, Tindall, 

 and Cox); "The Story of the English Public Health," 

 Sir Malcolm Morris, and "Infant and Young Child 

 Welfare,'' Dr. H. Scurfield (each in the new series of 

 English Public Health) {Cassell and Co., Ltd.); "The 

 Natural History of the Child," Dr. C. Dunn (Samp- 

 son Low and Co., Ltd.); and a new and revised 

 edition of " Mental Diseases," Dr. H. R. Cole (Uni- 

 versity of London Press, Ltd.). "The Chemical 

 Trade Year-Book " is in preparation by Messrs. 

 Bandon and Morris, of Red Lion Passage, W.C.i. 



Mr. F. Edwards, 83 High Street, Marylebone, has 

 just issued a catalogue (No. 391) of nearly 1000 items 

 relating to the Dominions, Colonies, and Depen- 

 dencies of the British Empire. It contains many 

 scarce works, is carefully classified, and will doubtless 

 interest many readers of N.^ture. Mr. Edwards has 

 also circulated a short list (No. 390) of new books at 

 remainder prices. Many of the volumes deal w^ith 

 scientific subjects. The catalogues will be sent free 

 upon application. 



The Scientific Attache to the American Embassy 

 informs us that the position of the solar prominence 

 referred to in the cablegram from Dr. L. A. Bauer 

 published last week (p. 311) was wrongly recorded. A 

 further message, states that the position should have 

 been given as 50ufh-south-west instead of U'esf-south- 

 west. 



OUR .ASTRONOMICAL COLUMN. 



The Planets. — The three bright planets which have 

 been so conspicuous during the last few months are 

 now leaving the evening sky. Jupiter will be in con- 

 junction with the sun on July 21, Saturn on August 25, 

 whilst Venus, which will be at greatest elongation 

 45° E. on July 5, is approaching greatest brilliancy 

 (August 8), and will be at inferior conjunction on 

 September 13. Mars is coming into view as a 

 morning star rising in the N.E. 



On the evening of July 2, at 9h. G.M.T., 

 a verv close and interesting approach of Venus 

 and Saturn may be observed in the W.N.W. sky. 

 The two objects will be separated by an apparent 

 distance of 10' of arc. Venus will set at about 

 10.30 G.M.T., and will be a brilliant object, offering 

 a strong contrast to the feeble appearance of Saturn 

 in the strong twilight. It will be interesting to 

 examine the two planets in the same field of view 

 with a good telescooe, and to note the great difference 

 in colour and brilliancy to the unaided eye. This 

 conjunction will form one of the most attractive 

 planetar>- configurations of 1919. It is true that the 

 conjunction of Venus and Saturn is not a rare event, 

 although one of the same character as that to which 

 we are now referring is ven' seldom observed, since 

 it will take place at a very convenient time for ob- 

 servation and the objects will be unusually near each 

 other. On a few evenings preceding and following 

 Julv 2 the changes in the relative places of \'enus and 

 Saturn will be considerable, and it will be enter- 

 taining to trace them from night to night. 



Admiralty Tide-tables. — A sentence in the Astro- 

 nomer Royal's report, noticed in last week's N.ature, 



NO. 2591, VOL. 103] 



I may have given rise to misconception. The day used 

 in the Admiralty tide-tables for the current year and 

 previously begins at midnight, and is divided into two 

 periods of twelve hours, a.m. and p.m. respectively. 

 The change to be introduced into the issue of the 

 tables for 1920 i~ that the hours will be numbered 

 from o to 23. 



THE NATIONAL PHYSICAL LABORATORY. 

 'T* HE annual visitation and inspection of the 

 ■*■ National Physical Laboratory by the General 

 Board took place on Tuesday, June 24. The numerous 

 visitors invited by the Board made a tour of the 

 laboratory, and were given an opportunity of seeing in 

 operation various subjects of intcre^st which are at 

 present being investigated at the laboratory. 



The engineering department exhibited an apparatus 

 for the determination of the absolute viscosities of 

 liquids at high pressures. The liquid under test is 

 arranged to flow through a capillary under a con- 

 stant-pressure difference, and its velocity calculated 

 from the indications of the instrument. The Lan- 

 chester worm-gear testing machine for obtaining the 

 efficiency of a worm-gear was shown. The machine 

 is so arranged that a pressure corresponding to a 

 transmission through the box of as much as 100 h.p. 

 can be obtained between the gear-teeth, it being neces- 

 sary to supply from an external source only the losses 

 in the gear and apparatus. In the apparatus used 

 for the measurement of journal friction, a tilt due to 

 a force of about i /300th of a pound weight acting at 

 the end of a 3-ft. lever could be measured. Varia- 

 tions of the coefficient of friction of the bearings due 

 to different oils could be observed with this apparatus. 

 Other exhibits in this department^ were the fol- 

 lowing : — An apparatus for tesbing the wear of 

 stranded cables, an extensometer for use at high tem- 

 peratures, a high-velocity impact testing machine, and 

 a wear-testing machine. 



The aeronautical department demonstrated how- 

 data for solving problems such as the following are 

 obtained in the wind channels: — (i) The mutual inter- 

 ference of air-screw and bodv, and the flow in the 

 neighbourhood of the air-screw; (2) the spinning of 

 aeroplanes ; (3) the balancing of rudders ; and (4) the 

 determination of the rotary derivations on SS. Zero 

 airship. Various models of complete machines and 

 a model of a mooring device for rigid airships were 

 exhibited. 



Demonstrations were given in the metallurgy 

 department of the rolling of high tensile aluminium 

 allovs. The recuperative gas furnace and the electric 

 "ring" furnace for high-temoerature work were seen 

 in operation. .\ chronograph for the direct plotting 

 of time-temperature observations in the form of 

 " inverse-rate " curves, as required for the heating and 

 cooling curves of metals and alloys, was demonstrated. 

 The curve olotted by the instrument may be regarded 

 as the differential coefficient of the simole time- 

 temperature curve reipresenting the observations. 



Tests on seaplane-floats were carried out in the 

 William Froude national tank. Two different types 

 of experiment were conducted : (a) on resistance, 

 running angle, and longitudinal stahilitv of a float 

 when planing on the water; and (b) on the impact of 

 a seaplane when alighting on water, measurements of 

 the deceleration and the blow received by the float 

 being made. 



In the large gauge-room, which was added to the 

 metrology department during the war for the purpose 

 of testing gauges used for munitions, were seen 

 different types of gauges and the methods of testing 

 them. During the busiest period of the war some 



