34« 



NA TURE 



[May 19, 1910 



papers by M. Tissot and M. Blein respectively. Both 

 direct attention to the influences of the thermoelectric 

 properties and the variation of the resistance with tempera- 

 ture of the materials used on their behaviour as coherers, 

 but Dr. W. H. Eccles, in a paper read before the Physical 

 Society of London on March 11, showed that the whole of 

 the properties of coherers could be explained, both quali- 

 tatively and quantitatively, by the Joule and Peltier heat 

 generated at the junction, and its effect on the resistances 

 of the materials forming the contact. 



Vol. vi. of the " Collected Researches of the National 

 Physical Laboratory " contains 200 pages quarto, and 

 consists of reprints of fourteen papers by members of the 

 staff, which have appeared in the pages of the technical 

 Press or the proceedings of scientific societies, most of them 

 during the year 1909. Several of these papers have already 

 been noticed in these columns, but we should like to direct 

 attention to the report of the committee appointed by the 

 Institution of Naval Architects to carry out the scheme 

 for establishing a tank at the laboratory in which the 

 experiments necessary for the advance of British shipbuild- 

 ing might be carried out. Ten experimental tanks are 

 already in use throughout the world, Japan possessing one, 

 but most of them are owned by private firms. An advisory 

 committee of naval architects has been appointed, which will 

 draw up a scheme of work to be done in connection with 

 the problems now awaiting solution. 



A SPECIMEN bottle of a concentrated combined toning and 

 fixing bath, issued under the name of " Combino," has 

 been sent for examination by Mr. P. F. Visick, 30 Finland 

 Road, Brockley. It gives good colours, and as it is only 

 necessary to place the print as taken from the frame into 

 the solution until the desired colour is obtained, it makes 

 the use of ordinary silver printing-out paper as simple as 

 the self-toning papers now so common. It is a gold-toning 

 solution, and the maker claims that it is stable when either 

 concentrated or diluted for use, and that double-toning, 

 that is, a variation of colour according to the depth of the 

 printing, is impossible. It is issued in 4-oz. bottles at one 

 shilling, and is diluted to five times its bulk for use. 



The changes undergone by stored coal are of considerable 

 importance, both from the point of view of liability to 

 spontaneous combustion and loss in calorific value. A 

 recent Bulletin (No. 38, Series 1909) from the University 

 of Illihois Engineering Experiment Station, by Messrs. 

 S. W'. Parr and W. F. Wheeler, is devoted to the con- 

 sideration of this subject. A critical abstract of all the 

 earlier work on the weathering of coal is given. This is 

 followed by a detailed account of experiments made to 

 determine the amount of disintegration and the changes in 

 weight and calorific value occurring in the grades of coal 

 found in Illinois and in the neighbouring States under 

 different conditions of storage. The losses in calorific value 

 for coal stored under water were found to be less than 

 with the usual storage in air, but the differences were not 

 great enough to warrant any changes in present storage 

 methods from this point of view alone. Storage under 

 water gives protection against spontaneously ignited fires, 

 and also lessens breakage losses, and hence may be worth 

 while resorting to in certain cases. 



Messrs. Reynolds and Branson, Ltd., have just 

 issued a comprehensive catalogue of photographic requisites 

 containing particulars of many new cameras and 

 accessories. 



•■V WORK on the birds of Dumfriesshire, by Mr. H. S. 



• Gladstone, will shortly be published by Messrs. Witherby 



and Co. The book will give an exhaustive account of the 



present-day status and past history of all the birds of the 



NO. 2 II 6, VOL. 83] 



county, and will be illustrated by ' photographic plate^ and 

 a map. It will be published by subscription, and- in a 

 strictly limited edition. 



. An Aviation Association of Ireland has been formed, with 

 Mr. J. B. Dunlop as president. Dr. W. E. Lilly and Mr. 

 J. C. Peary as vice-presidents, and Mr. D. O'B. Gill, 

 19 Herbert Street, Dublin, as honorary secretary. .\ 

 lecture was delivered before the association on February S 

 by Dr. Lilly, and has now been reprinted by the Moti>r 

 News, of Dublin. 



Messrs. J. and A. Churchill have a new edition of 

 vol. ii. of " Allen's Commercial Organic Analysis " just 

 ready for publication. This volume has been re-written 

 under the editorship of Dr. H. Leffmann and Mr. W. A. 

 Davis. The subjects are : — fixed oils, fats and waxes, 

 special characters and methods, butter fat, lard, linseed 

 oil, higher fatty acids, soap, glycerol, cholesterols, wool 

 fat and cloth oils. 



A NEW catalogue of lenses has just been issued by 

 Messrs. J. H. Dallmeyer, Ltd. Among the new types of 

 lenses of which particulars are given are a new series of 

 Dallmeyer stigmatics, the single components of which are 

 dissimilar and may be used separately; improved forms 

 of the well-known " Adon " lens, which gives, for the 

 same camera extension, a much larger picture than an 

 ordinary lens ; and a new telephoto combination working 

 at //lo, and giving variable magnification. The capabili- 

 ties of the various lenses and combinations are illustrated 

 by some striking pictures. 



OUR ASTRONOMICAL COLUMN. 



Halley's Comet. — The observations of Halley's comet 

 during the present month have shown that, in brightness, 

 it has at least come up to general expectation. Numerous 

 arnateur observers report having seen it as a fairly con- 

 spicuous object before dawn. 



If Dr. Ristenpart's calculated time for perihelion is 

 correct, the comet transitted the sun between 3h. 4m. and 

 4h. 4m. this morning (May 19), and any special phenomena 

 which could be caused by the passage should be fully re- 

 ported to some competent authority. From Dr. Holet- 

 schek's results it appears likely that the brightest part of 

 the tail would not extend so far as the earth, but meteors 

 from, the outlying, and possibly curved, extremity should 

 be looked for, carefully noted, and reported. Recent 

 observations indicate, however, that the tail is quite long 

 enough to extend past the earth. 



Mr. G. Gillman reports that he has continued his 

 observations at Aguilas, Spain, on each successive morning, 

 and found that at 3h. 20m. on May 13 the tail was par- 

 ticularly well defined. It was visible to the naked eye 

 almost to a line joining Pegasi and a Aquarii, which 

 means that the apparent length was some 43°. This is 

 the greatest length yet recorded by him. 



Mr. C. Leach also sends another sketbh showing the 

 extent of the tail as he saw it with the naked eye al 

 3h. 45m. a.m. on May 8. This shows the head of the 

 comet in line with a Andromedae, 7 Pegasi, and Venus 

 with the tail extending, nearly parallel to the south sidi 

 of the Great Square, to a greater length than the distance 

 between 7 and o Pegasi ; the tail was perfectly straight 

 Mr. Leach also sends a sketch and note, taken from i 

 local paper, describing the comet as seen by Prof. Attilie 

 Sesta, at Palermo, at 3h. 25m. on May 8. Thi; 

 corroborates Mr. Leach's own observation, and adds tha 

 the nucleus was very bright (visible until 5 a.m.), and tha 

 the diaphanous tail exhibited rectilinear margins whicl' 

 formed a small angle at the head; I 



A number of positions of the comet during November! 

 February are published by Dr. Rambaut in the Monthl; 

 Notices (Ixx., 6). The places were determined from photo 

 graphs, taking astrogra'phic stars for reference points. 



In Asironomische Nachrichten, No. 4408, Herr J. Fran 

 considers the passage of the earth through the tail am 



