528 



NA TURE 



[April 22, 1922 



some of the results of this inquiry was included in 

 the article on " The Migration of British Swallows " 

 in Nature of March 16. 



The Ministry of Agriculture announces that bees 

 can now be examined for the presence of the 

 Acarine Disease on payment of a fee of 2s. for each 

 sample submitted. Live bees only must be sent, and 

 about 30 specimens should be taken from off the 

 combs and packed in a small cage or box provided 

 with ventilation-holes. A piece of muslin should be 

 fastened across the inside for the bees to cling to 

 during transit. A supply of candy sufficient to last 

 for a few days, or a lump of sugar moistened with 

 water, should be wrapped in muslin and fastened 

 firmly to the inside of the box. The latter should 

 be addressed to the Ministry of Agriculture, 4 White- 

 hall Place, London, S.W.i, and the name of the sender 

 should be written on the reverse side of the label, but 

 crossed through to prevent an error in transit. The 

 remittance should be sent under a separate covering 

 letter with as much information as possible concerning 

 the bees. Payment must be made by postal order 

 or cheque. 



On March 22 at a meeting of the Institution of 

 Aeronautical Engineers a paper was read by Mr. 

 Manning on " Seaplane Design," and on March 31 

 Mr. H. P. FoUand dealt with the subject of aircraft 

 design generally. The programme of future fixtures 



includes papers by Captain Sayers on " Some Un- 

 settled Problems of Aeroplane Design" and by Major 

 Hume on " The Seaplane's Place in Aviation." Visits 

 have been arranged to the works of the De Haviland 

 Aircraft Company, Simms Motor Units Ltd., the 

 National Physical Laboratory, the South Kensington 

 Museum, and the Croydon Aerodrome. The secretary 

 is Mr. L. Howard Flanders, 60 Chancery Lane, and 

 the president. Col. J. T. C. Moore-Brabazon, M.P. 



We have received from Messrs. Baird and Tatlock, 

 of Cross Street, Hatton Garden, a copy of their new 

 (1922) catalogue of apparatus for use in physiological 

 and other laboratories where similar apparatus is 

 required. The worker will find it a very valuable and 

 an almost complete list of the instrum.ents at present 

 available for teaching and research purposes. In 

 the latter case, it frequently happens that new 

 apparatus has to be designed and fitted up to solve 

 new problems ; but the list sent to us will be of 

 much assistance in giving information of what is 

 actually to be obtained for the purpose in view. We 

 note that the collaboration of physiologists has been 

 obtained in the selection of the material to be included 

 and the presence of apparatus for physico-chemical 

 measurements is to be welcomed. The instruments 

 for convenient measurement of electrical conductivity 

 and potential have been somewhat difficult to obtain 

 in recent years in England. The prices on the whole 

 appear to be reasonable. 



Our Astronomical Column. 



The Shower of Lyrids. — These meteors may be 

 expected to return on the night of April 21, and as 

 the moon will be absent this year at the time of the 

 maximum display, they should be well observed. 

 The best hour at which to witness the event will 

 probably be near midnight, for in the morning hours 

 on April 22 the earth is likely to have passed through 

 the denser part of the stream. The shower certainly 

 lasts ten days, but it appears in its most active stage 

 for a short period only. Of late years the meteors 

 of this system have not been visible in striking 

 abundance, and it is an unfortunate circumstance that 

 its period of revolution is unknown. A brilliant ex- 

 hibition of the meteors may occur in any year, and 

 quite unexpectedly as in 1803 and 1851. 



The Position of Neptune's Equator. — It has 

 long been known that the plane of the orbit of Nep- 

 tune's satellite Triton is changing its position. The 

 only probable cause is the oblateness of Neptune, and 

 it follows that the orbit plane makes a considerable 

 angle with the planet's equator. By plotting out the 

 poles of the satellite's orbit at different epochs we get 

 an arc of a small circle, the centre of which is the pole 

 of Neptune's equator. The latest determination of 

 the position of the latter pole is that made by Mr. 

 Arthur Newton {Pop. Ast., March 1922). Making use 

 of 1500 observations of the satellite, made from 1864 

 to 1908, he gives R.A. 19 h. 17 m., N. Decl. 38°- 3 as 

 the northern end of Neptune's axis. The pole of the 

 satellite's orbit describes a circle round this, of radius 

 14°- 7, in 425 years. There is little doubt that Nep- 

 tune's rotation is retrograde ; this has been verified 

 for Uranus by the spectroscope, the period of io| h. 

 being found at the same time. In the case of Uranus 

 the equator evidently coincides with the orbit 



NO. 2738, VOL. 109] 



planes, since these are all practically coincident and 

 no change in them has been detected. 



Determination of Star Magnitudes by a 

 Thermopile. — J. Schilt has devised a new method 

 of determining photographic star-magnitudes, which 

 he describes in Bull. No. 10 of the Astr. Inst, of the 

 Netherlands. The Ught and heat from a lamp are 

 focussed by a lens on a small circle of the plate, 

 which is somewhat larger than any of the star-images ; 

 these images are then moved in succession into the 

 circle of light, and the amount of heat absorbed by 

 the image is measured by the galvanometer of the 

 thermopile. The process is rapid, the equilibrium 

 temperature being attained in three seconds. The 

 probable error, deduced by comparing the measures 

 of two exposures on the same plate, is found to be 

 0-02 mag., whereas that from the method of diameter 

 of image is o- 11 mag. 



The most striking advantage of the new method is 

 that it gets rid of practically all error due to variation 

 in the shape of the image with varying distance from 

 the centre of the plate. It also gets rid of the error 

 that arises in the star diameters in plates taken with 

 a refractor, due to the chromatic aberration which 

 depends on the star's colour. In fact the method 

 appears to give the integrated amount of darkening 

 of the film independently of the size or shape of the 

 image. This is verified by the application of the 

 method to some of the polar plates taken with the 

 60-inch reflector at Mt. Wilson. The tables show 

 that it gives good results up to a distance of 44 mm. 

 from the centre of the plate, whereas Scares had found 

 that the diameter method needed corrections of about 

 half a magnitude at a distance of only 20 mm. The 

 method would seem to have a large field of usefulness 

 in the photometry of faint stars on reflector plates. 



