March 24. 1910] 



NATURE 



109 



In Xo. 5 of the Revue generate des Sciences (March 15, 

 p. 177) M. G. Renaudot makes the interesting suggestion 



lai the periodicity of comets, or of Halley's comet 

 specially, was known and recognised by the ancient 

 Hebrews. He bases this suggestion on a passage in the 

 'J'almud, where one of two voyagers explains that he has 

 laid in a stock of flour, rather than bread, because " There 

 is a very bright star which appears every seventy years 

 and which deceives navigators. Thinking that she may 

 -urprise us during this voyage, and so prolong our journey, 

 I have provided the flour." M. Renaudot gives reasons 

 why the expected object should be considered as a comet, 

 rather than as a long-period variable, for instance, explains 

 ;hat 70 instead of 75 is in accordance with the habit of 

 giving round numbers, and states that the existence of 

 the two important personages between whom the dialogue 

 took place is well attested historically. 



A second edition of Prof. Turner's British .Association 

 address on '' Halley's Comet " has just been issued by the 

 Clarendon Press at the price of is. net. 



Ephemeris for Eros, 1910. — To facilitate observations 

 of Eros during the coming opposition. Prof. Wendell has 

 computed an ephemeris, which is published in Circular 

 No. 153 of the Harvard College Observa.torj-. Unfortu- 

 nately, the planet will not be observable in these latitudes, 

 its declination at opposition (May 23) being 46° 31' S., but. 

 as its orbit and light-variations are so peculiar, it is hoped 

 tJiat a number of obser\ations will be secured at southern 

 observatories. . ' ' ' ' 



Prok. Doberck's DotrBLE-ST.\R Observations. — In con- 

 tinuation of a list which appeared in Nos. 4327-8 of the 

 Astronomische Xachrichten, Prof. \V. Doberck now 

 publishes his obser\ations of a great number of doubles, at 

 Sutton during 1909, in Nos. 4394-5 of the same journal. 

 Each observation is recorded separately, and the position- 

 angle and distance of each pair are given for the mean 

 epoch of observation. 



Daniel's Comet, 1909^.— A photograph of Daniel's 

 comet (1909^) was secured by Dr. Wolf on February 28, 

 when the comet's magnitude was 15-0. It now appears 

 that this comet belongs to the Jupiter, and not to the 

 Uranus, family of comets, as was at first su^iected. 



THE XATIOXAL PHYSICAL LABORATORY 

 IS 1909. 



T^ HE general board of the National Physical Laboratory* 

 held their annual meeting at the laboratorv* on 

 Friday last, March 18, when the report of the work done 

 during 1909 was presented, and the programme of work 

 proposed for the year 1910 was approved. The chair was 

 taken by Sir Archibald Geikie, as president of the Royal 

 Society, and Lord Raylejgh, chairman of the executive 

 committee, was also present. A large number of guests 

 were invited to inspect the various departments of the 

 laboraton*. 



Two new branches of the -work claim attention this 

 year. The first of these is the national experimental tank 

 for experiments on ship models, which is being constructed 

 at a cost of about 20,000/., provided by the generosity of 

 Mr. A. F. Yarrow. A maintenance fund for carrying on 

 the work of the tank for the first ten years has also been 

 provided with the aid of the Institution of Naval Architects. 

 With regard to the details of the working of the tank, 

 assistance will be given, under a scheme printed in the 

 laboratory report, by an advisory committee composed of 

 members nominated by the Institution of Naval AJ-chitects 

 and by the executive committee of the laboratory". 



The tank itself, and the office buildings and workshops 

 lequired, are now nearly completed. The length of the 

 tank is 500 feet at the full depth of 12^ feet, and the 

 width 30 feet. At the north end are docks for receiving 

 the models, while at the south end is a shallow " beach " 

 for breaking the waves. As was shown by Dr. Glazebrook 

 in a report orfsented in March, iQoq. to the Institution of 

 Naval Architects, models up to 20 feet in length and 3 feet 

 in breadth can be tested in a tank of the width stated 

 without any appreciable effect on the results due to the 

 sides. 



The models will be towed along by a carriage, electrically 

 driven, spanning the tank and running on rails on either 

 NO. 2108, VOL. 83] 



side. This carriage carries the observers and dynamo- 

 meters. The models will usually be made of paraffin wax, 

 and the equipment will include special model-cutting 

 machinery. None of this apparatus, however, is yet 

 installed, and we hope, at a later date, to give a more 

 detailed account of the tank and of the special apparatus 

 employed. 



Ihe second large development of the work during 1909 

 is the formation of a division for research in aeronautics. 

 This work has been undertaken in accordance with the 

 announcement made by the Prime Minister in the House 

 of Commons on May 5, 1909, and is under the general 

 superintendence of the .Advisory Committee for Aeronautics 

 then appointed. Rapid progress has been made during the 

 year with the provision of the necessary equipment for the 

 experimental work at present planned. This includes an 

 air channel 4 feet square in section by 20 feet long for 

 general work in aerodynamics, a whirling table 60 feet 

 in diameter for propeller testing, in a special building 

 80 feet square ; dynamometers for motor testing, with 

 arrangements for an air blast for air cooling ; and two 

 wind towers for work on a large scale in the open. All 

 this apparatus has been erected, and experiments have 

 been for some time in progress. The division is under the 

 charge of Dr. Stanton as superintendent of the engineering 

 department, and his great experience on the subject of 

 wind pressure will be especially valuable. To provide the 

 increased accommodation necessary, two more bays have 

 been added to the engineering building. 



The testing of balloon fabrics also constitutes an 

 important branch of the work. Tensile and bursting tests 

 have been carried out in the engineering department, while 

 in the chemical department a special apparatus has been 

 devised for the determination of the permeability to 

 hydrogen. We may, perhaps, be able on another occasion 

 to give further particulars of the aeronautical equipment. 



Turning now to the physics department, in the electrical 

 standards division good progress has been made with the 

 erection of the Lorenz apparatus for the determination of 

 the ohm in absolute measure, and this is now nearly 

 complete. The coils, wound on marble cylinders, have 

 been made in the laboratory ; the main part of the 

 machine, by the kindness of Sir Andrew Noble, has been 

 constructed at Elswlck. The determinations to be made 

 with this will be the chief work in this division during the 

 current year. W'ith regard to standard cells, a research 

 has been in progress to determine the limits of temf)erature 

 between which cadmium amalgams of various concentra- 

 tion can be usefully employed, the results of which were 

 communicated to the Physical Society by Mr. F. E. Smith 

 in a recent paper. The general conclusion arrived at is 

 that an amalgam containing 125 per cent, of cadmium 

 cannot safely be used below 12° C, and the substitution 

 of a 10 per cent, amalgam is recommended. This can be 

 relied upon to give constant results at a definite temperature 

 for all temperatures between 0° and 51° C. 



We have previously made reference to the new order 

 in council lately issued relative to the electrical units, 

 the outcome of the work of the International Conference 

 in London in 1908. To complete the work of the confer- 

 ence, representatives from the chief standardising labora- 

 tories are to meet at Washington shortly to continue 

 jointly the researches necessary to decide on a definite value 

 for the E.M.F. of the Weston cell. 



Another matter in w-hich international cooperation is 

 being arranged is the question of the methods of measuring 

 hysteresis and eddv loss in steel sheet. A modification of 

 the Epstein method has recently been devised by the Bureau 

 of Standards which appears to give accurate results, and 

 investigations relative to this question have been in progress 

 at the laboratory. 



In the electrotechnics division much attention has been 

 given to perfecting the equipment for alternating-current 

 measurements. Features of special interest are the non- 

 inductive ■ water-cooled tube resistances, described in a 

 paper communicated to the Institution of Electrical 

 Engineers, and the quadrant electrometer for use as an 

 alternating-current wattmeter. The 100,000-volt trans- 

 former equipment ■ has been completed, and has been 

 employed in an investigation into the properties of different 

 varieties of ebonite, while a research on insulating materials 

 is in progress. In the photometry section a, considerable 



