January 9. 1908J 



N'A TURE 



233 



variation of the electrical resistance of pure metals down 

 to very low temperatures, by Prof. H. Kamerlingh Onnc 

 and Mr. J. Clay. They find fhat the influence of vcr 

 small amounts of impurities, although insignificant dow 

 to a temperature of -200° C, at lower temperatures be 

 romes very marked. They express the effect by writin; 

 the resistance found equal to that of the pure metal ^\u 

 a constant, depending on the amount and nature of thi 

 impurity. Platinum, gold, silver, lead,, bismuth, an( 

 mercury have been tested between 16° C. and —260° C. 

 and the results agree fairly well with those obtained four- 

 teen years ago by Sir James Dewar and Prof. Fleming 

 down to the temperature of liquid air. They differ con- 

 siderably at low temperatures from the results recently 

 published by Mr. G. Niccolai, of Pisa, and it seems prob- 

 able that the differences are due to the latter not having 

 expressed his temperatures in terms of the international 

 constant-volume hydrogen scale. 



Messrs. N. Zanichei.i.i, of Bologna, have published as 

 No. ID of their series of " .Attualit^ Scientifiche " a recent 

 address delivered by Prof. A. Righi before the Italian 

 Society for the Advancement of Science ; the lecture is 

 entitled " New Views on the Ultimate Nature of Matter," 

 and covers a wide field, dealing with the nature of atoms 

 and electrons, and embracing the question of ordinary and 

 colloidal solution. 



The Iron and Steel Institute has published in No. 3 

 of its journal a detailed account of the visits and 

 excursions during the meeting of the institute held at 

 Vienna in September last. The report contains a large 

 number of interesting particulars of works and mines 

 visited by the members, together with a great deal of 

 information regarding the development of the iron and 

 steel industry within the Austrian Empire ; the account is 

 illustrated by several photographs. 



From Mr. A. B. Porter (" The Scientific Shop "), 324 

 Dearborn Street, Chicago, U.S. -A., we have received a 

 number of circulars containing descriptions and prices of 

 a large number of pieces of physical apparatus, many of 

 which are novel in character and for use in special ex- 

 periments. The different sets cannot be mentioned here, 

 but the catalogue is an interesting item for anyone engaged 

 in science teaching or research ; many of the sets of appar- 

 atus are well illustrated and described. Mr. Porter has 

 ;ilso favnured us with his "Catalogue D," giving descrip- 

 tions, illustrations, and prices of numerous optical parts. 

 Telescope objectives and mirrors, prisms, echelon and 

 diffraction gratings, photographic lenses, &c., are included 

 in this list. .As showing the enterprise of this firm, we 

 would note that Mr. Porter quotes a price of 38,000 dollars 

 for a paraboidal mirror, grade \, of 84 inches diameter 

 and 40 feet focal length ; " prices of other sizes up to 

 10 feet in diameter will be quoted on request." 



The virtues of celluloid as a material suitable for the 

 sharp and clean divisions of scales or slide rules, or in its 

 transparent form as an edge for T-squares or for set- 

 squares, are well known. Messrs. Casella and Co. have 

 availed themselves of these properties, and of another, viz. 

 that fine sharp lines may be ruled upon it with some 

 opaque black dye, in the convenient area scale. White and 

 Bean's" patent, which they have put upon the market. 

 This is nothing more than a group of parallel lines 

 alternately full and dotted one-quarter of an inch apart. 

 The set of parallel lines is laid over the figure the area 

 of which is required, e.g. a steam-engine diagram, taking 

 care that it is so placed that the extremities of the area 



lie half-way between a pair of lines on each side. Then 

 the sum of the included lengths of all the parallel lines 

 is found by marking them off on the edge of a strip of 

 paper. The total length in inches divided by four gives 

 the area in square inches. In order to avoid the necessity 

 of dividing by four, a scale is attached in which the unit 

 distance is 4 inches, and this is divided into one hundred 

 parts, and so by direct application of the strip of paper 

 to this scale the area may be read directly. Alongside of 

 the inch scale is another scale of equal parts such that 

 the length of 4 inches read on this scale appears as 6.45. 

 From this, therefore, square centimetres may be read. 

 When less accuracy is required, alternate lines only need 

 be used, and the result multiplied by two. In the example 

 submitted the linear dimensions are all short by i in 150, 

 which would make the areas come out too much by 



The current issue of Mr. Charles Baker's quarterly 

 catalogue of second-hand optical and other instruments is 

 now available. The list contains particulars of about 1250 

 pieces of apparatus on sale in this particular department 

 of Mr. Baker's establishment. 



The list of electrical novelties just published by Messrs. 

 F. Darton and Co., of St. John Street, London, E.G., 

 contains numerous illustrated descriptions of pieces of 

 electrical apparatus likely to prove acceptable presents to 

 boys with interest in science. The catalogue also includes 

 various applications of electricity to domestic purposes, in 

 addition to many different patterns of widely used electrical 

 instruments. 



Messrs. James Woollev, Sons and Co., Ltd., publish 

 a compact and useful " Reference Book and Diary for 

 1908," intended for science teachers and students. The 

 pocket-book contains many convenient tables of constants, 

 brief hints as to the use of instruments, " first-aid " notes, 

 and some advertisements, in addition to the usual form of 

 diary. The price of the book is one shilling bound in 

 cloth and two shillings in leather covers. 



The " Science Year-book and Diary for IQOS," edited 

 by Major B. F. S. Baden-Powell, and published by Messrs. 

 king. Sell and Olding, Ltd., contains 152 pages of useful 

 scientific information, a full-page diary for the year — 

 each page being provided with useful astronomical and 

 meteorological data for the day — and numerous blank 

 pages for notes, cash accounts, and other memoranda. 

 The frontispiece is a portrait of Sir Norman Lockyer, 

 K.C.B., F.R.S. New names have been added to the bio- 

 graphical section, but it is difficult to understand what 

 plan has been adopted in selecting names for inclusion in 

 this list. The price of the volume is 55. net. 



Messrs. Newton and Co., 3 Fleet Street, E.C., have 

 submitted to us a specimen of an instrument termed the 

 " Vitascope," devised for the examination of small living 

 creatures under natural conditions. The instrument is in 

 the form of a telescope, about i\ inches in diameter and 

 a foot in length when closed, and by a novel combination 

 of lenses it enables a magnification of about twelve 

 diameters to be obtained at a distajice of 20 inches from 

 the object under observation, and sixty diameters at a 

 distance of about 5 inches. With these magnifications, the 

 observation of insects in flowers or of other small living 

 objects, at a suitable distance from them, becomes a 

 pleasurable and instructive pastime. The instrument has 

 a pillar, which can be screwed upon the top of an ordinary 

 camera stand for use in the garden to observe the stru."- 



NO. 1Q93. V L. 77] 



