598 



NATURE 



[October io, 1907 



Burgess. They find that at temperatures about 1500° C. 

 platinum departs farthest of all the substances tried from 

 radiating as a perfectly blacU body, while carbon most 

 nearly approximates to a black body. All the filaments 

 .used are thus selective radiators, and are more efficient 

 Juminous radiators than a black body, the order being for 

 the same temperature — platinum, tantalum, tungsten, 

 carbon. The superiority of tantalum and tungsten over 

 carbon filament lamps is to some extent due to this fact, 

 which is further emphasised by the higher temperature at 

 which they can be worked, the light emitted varying 

 nearly as the twelfth, while the energy supplied varies 

 only as the fifth, power of the temperature. 



The Health Education League of Boston, Massachusetts, 

 has sent us two copies of new booklets published in con- 

 -tinuation of the series noticed in a recent number of 

 Nature (September 12, p. 508). In one of the booklets 

 (No. 12) Dr. M. H. Bailey deals with " Emergencies," 

 and in the other Miss A. F. Rogers and Dr. J. H. 

 McCoUom describe " Microbes: Good and Bad." 



A SECOND edition of Prof. J. Reynolds Green's " Intro- 

 duction to Vegetable Physiology " has just been published 

 by Messrs. J. and A. Churchill. The 

 price of the work is los. 6d. net. 



A SECOND edition (third impression) 

 of Mr. \V. P. Workman's " School 

 Arithmetic," which is a school cours' 

 adapted from " The Tutorial Arith- 

 metic," has been published by Mr. 

 \V. B. Clive. 



We have received from Mr. C. 

 Baker, of High Holborn, London, the 

 October issue of his classified list of 

 second-hand instruments and of new 

 pieces of apparatus recently intro- 

 duced. The catalogue contains a de- 

 scription of more than a thousand 

 pieces of apparatus, together valued 

 at more than 6000Z. Those who arc 

 contemplating the purchase of micro- 

 scopes, telescopes, spectroscopes, and 

 other physical apparatus would do 

 well to examine this catalogue. 



OUR ASTRONOMICAL COLUMN. 



The Physical Nature ok Meteor Trains. — .\n interest- 

 ing discussion of the nature of meteor trains is published 

 in No. 2, vol. xxvi. (p. 95, September), of the Astro- 

 physical Journal by Prol. C. C. Trowbridge. Prof. Trow- 

 bridge, believing that valuable information concerning the 

 upper layers of the earth's atmosphere may be thereby 

 deduced, has compiled a catalogue of observed meteor 

 Irains, and for several years has made a comparative study 

 of the data, at the same time making a study of the 

 phenomena of gas phosphorescence. The discussion of 

 altitudes leads to the conclusion that there is a definite 

 layer of the earth's atmosphere, probably some fifty to 

 sixty miles high, where the conditions are favourable to 

 the production of the peculiar glow constituting a meteor 

 train. Prof. Trowbridge believes that the secondary 

 appearance of duality, so frequently observed in meteor 

 trains, is due to the probable tubular form of the trains. 

 The train itself is probably a tube of gas and particles of 

 meteor dust, rendered phosphorescent by some temperature 

 or electrical effect produced by the meteor's passage. The 

 rate of diffusion and the colour of meteor trains agree with 

 similar phenomena observed in phosphorescent air in the 

 laboratory. 



The Pulkowa Eclipse Expedition to Turkestan, 

 January, 1007. — -An interesting account of the expedition 



Observing Station of the Eclipse Exp:dition at Ura-tjube, Russian Turke 



The general committee of the Dr. Frcam memorial fund 

 has confirmed the following resolution, which was passed 

 at a recent meeting and accepted by the Board of Agri- 

 culture and Fisheries :— " That the Fream Memorial Fund 

 shall be invested in the name of the Board of Agriculture 

 and Fisheries or of an official trustee selected by the 

 Board, and shall be administered by the Board of Agri- 

 culture and Fisheries, and that the income shall be applied 

 by way of a Fream memorial prize of books to be com- 

 peted for in each year by students in the science of agri- 

 culture, and so that as long as an examination is held 

 by the National .Agricultural Examination Board for the 

 national diploma in agriculture the prize shall be awarded 

 to the person who obtains the highest marks in such 

 ■e.xamination." A sum of about 2ooi. is available for the 

 purpose of the memorial. 



Photographers will study with interest the new edition 

 of the catalogue of photographic apparatus and materials 

 recently issued by Messrs. Marion and Co., Ltd., of Soho 

 Square, London. The full descriptions and carefully tabu- 

 lated particulars as to sizes and prices contained in this 

 -well-illustrated list should render the choice of material 

 ■easy and expeditious. 



NO. 1980, VOL. 76] 



dispatched from the Nicholas Central Observatory, 

 Pulkowa, to observe the eclipse of January 13, 1907, is 

 given in No. 18, vol. ii., of the Mitteilungen der Nikolai- 

 Haupsternwaric sit Pulkowo. The site chosen for the 

 observation of the oclip.se was near the small town of 

 Ura-tyube, in the Sainarkand district of Turkestan, and 

 there the various instruments were erected on Deceinber 

 31, iqo6. The accoinpanying illustration, reproduced from 

 the Mitteilungen, gives some idea of the conditions under 

 which the observers worked, and shows the instruments 

 in position. The long tube on the left is the coronagraph 

 of 5 inches aperluro and 43-5 feet focal length, with which 

 M. Hansky hoped to obtain photographs showing details 

 of the inner corona and prominences ; as may be seen, this 

 instrument was pointed directly to the sun's place at the 

 moment of mid-totality. With the photographic refractor 

 of short focus, it was planned to obtain five photographs 

 of the corona with various coloured screens and on different 

 plates. In addition to these, an attempt was to be made 

 to photograph the spet^trum of the corona from C to the 

 ultra-violet, and >[. Hansky also proposed to carry out 

 photographic photometric researches. 



Heavy snowfall prevented this programme from being 

 carried out on the day of the eclipse, but some interesting 

 observations of the terrestrial colour effects and the 

 shadow-bands were made. M. Hansky also discusses some 



