March 31, 19 10] 



NATURE 



139 



is probably not the case. No attempt is made to find the 

 effect of varjing natural ventilation. 



Mr. Hermans Gewecke sends us a dissertation on the 

 influence of changes of internal structure on the physical 

 properties of copper, electrical conductivity and density 

 being the properties chiefly considered. In this pamphlet 

 of ninety-three pages the author discusses at length the 

 ''xperimental results and theoretical conclusions of previous 

 rkers in the same field, and also describes his own 

 isurements of electrical conductivity and determinations 

 : density carried out on a series of copper wires drawn 

 "der known conditions. His results show that the effects 

 wire-drawing depend upon two actions, which occur 

 ■ ultaneously, but to a different relative extent when the 

 circumstances of the drawing process are altered. These 

 two actions are longitudinal extension and lateral com- 

 pression, and their effects on conductivity- and densit}' are 

 opposite in character. The net result is that, as wires 

 become more severely hard-drawn, their density first in- 

 creases and then decreases again, while the electrical con- 

 ductivity is reduced — in some cases to an extent exceeding 

 1-5 per cent. Mr. Gewecke has also studied the anneal- 

 ing process in these wires, but although a temperature of 

 210° C. is found to mark the beginning of rapid annealing, 

 this temperature is found to var>' with the duration of 

 heating. This supports the view of Turner and Levy that 

 the change in the copper is rather of the nature of a con- 

 tinuous re-arrangement of structure than a transformation 

 from one allotropic phase into another, as suggested by 

 Dr. Beilby. 



We have before us a draft report of the science stand- 

 -, committee of the Concrete Institute relative to a pro- 

 'A standard algebraical notation for formulae and 

 I alculations employed with reference to reinforced concrete. 

 It would appear that this was considered last September 

 Copenhagen by a committee of the International Com- 

 -sion on Reinforced Concrete (established by the Inter- 

 narional Association for Testing Materials), which approved 

 of a three-alphabet system, the three alphabets employed 

 to be Roman capital letters, Roman small letters, and 

 Greek smalls. The principle of the initial letter is also 

 adopted in the report, though this cannot be made a basis 

 for agreement with Continental nations ; it is held, no 

 doubt rightly, that the use of a self-explanator\' notation 

 is in this matter more important than international 

 uniformit}-. The use of Latin smalls for linear dimensions, 

 intensities of forces, &c., and constants, Latin capitals 

 for areas and volumes, and total forces, Greek smalls for 

 angles and constants, is recommended. The notation can 

 be extended by the use of subscript letters ; thus B^ may 

 be used for *' bending moment at the centre of a beam." 

 The scheme is not put forward as part of a comprehensive 

 sjstem ; indeed, it is pointed out that letters fail if any 

 attempt is made at a comprehensive system for engineering 

 formulae alone, not to speak of physics generally. It is, 

 however, clearly desirable that some general plan should 

 be agreed upon, by engineers at least, before an attempt 

 is made to work out a detailed notation for each branch 

 of engineering work. It may be that the only plan possible 

 is the adoption of some general principles, and those sug- 

 gested are sufficiently in accord with existing usage. 

 Possibly the Engineering Standards Committee may be 

 able to look into the matter. 



A PAPER on compounding and superheating in Horwich 

 Womolives was read at the Institution of Mechanical 

 Engineers on March 7 by Mr. George Hughes, the chief 

 mechanical engineer of the Lancashire and Yorkshire Rail- 

 way. A number of comparative tests have been made by 

 NO. 2109, VOL. 83] 



the author on compound and simple engines, leading to 

 the conclusion that the compound engine is more economical 

 and efficient than the simple. The compound engine 

 developed a comparatively greater pull on the draw-bar for 

 the same indicated horse-power. The Aintree to Accring- 

 ton trials show an economy of 23 per cent., and the Goole 

 to Smithy Bridge tests an economy of 225 per cent., in 

 favour of the compound, based on the steam consumption 

 per indicated horse-power. On the basis of total steam 

 consumption per hour, the savings in these trials are 

 397 and 333 per cent, respectively. In fuel consumption 

 the savings by the compound per indicated horse-power 

 per hour are 16 per cent, and 83 per cent, respectively. 

 .\s the horse-powers developed by the compound are less 

 than for the simple engine, the total fuel savings are 

 36 per cent, and 23-7 per cent, respectively. Using 

 Schmidt's system of superheating on a six-wheeled coupled 

 goods engine, comparative trials show an economy in coal 

 of 1293 per cent, per ton-mile for the superheater. Tests 

 on five passenger engines having Schmidt's superheaters, 

 extending over some months, show a coal saving of 21-4 

 and 21-9 per cent, per ton-mile, computed from the drivers' 

 and guards' returns. Mr. Hughes is to be congratulated 

 on his success in dealing with ver\- difficult problems when 

 applied to locomotives. 



As improved form of mouth blow-pipe is submitted for 

 inspection by Messrs. \V. and J. George, Ltd., Great 

 Charles Street, Birmingham. It is a burner and air-tube 

 combined, connecting directly with the gas supply by means 

 of rubber tubing, and dispensing with a Bunsen burner. 

 A metal collar at the mouth-piece end keeps the latter clean 

 by preventing it from coming into contact with the bench 

 when laid down. A similar collar at the burner end keeps 

 the flame from scorching the wood. If desired, the instru- 

 ment can be. clamped to a retort stand for use at any 

 convenient height or angle, and it serves instead of a foot 

 blow-pipe for many small operations, such as flame, char- 

 coal, and " bead " tests, and light glass-blowing. The 

 article is neatly and strongly constructed, and for con- 

 venience of renewal the several parts are made to a 

 standard size. 



The January number of the Bulletin de la Societi 

 d' Encouragement pour I'lndustrie nationale contains two 

 reports by A. Moreau on two forms of road-tarring 

 apparatus, due to MM. J. Lassailly and J. Vinsonneau 

 respectivelv. The tar has to be extracted from the barrels, 

 warmed to a temf)erature sufficient to reduce its viscosity 

 and remove water, and applied to the road as uniformly 

 and as rapidly as possible. In the first apparatus of M. 

 J. Lassailly all these operations are carried out by steam, 

 and require a minimum of skilled control. The 

 Vinsonneau apparatus warms the tar to 80° C. by a 

 thermosiphon heated by a petrol burner, and distributes it 

 by means of compressed air. The cost of superficial 

 tarring by either process is from 8 to 10 centimes per 

 square metre treated. 



A SECOND revised edition of the valuable little book on 

 " Butter-making on the Farm," by Mr. C. W. Walker- 

 Tisdale and Mr. T. R. Robinson, has just been issued 

 by the publisher, Mr. J. North, Ofliice of the Dairy World 

 and British Dairy Farmer. The original work was favour- 

 ably reviewed in N.\ture of February 12, 1903, and the 

 revised edition should secure for it many new readers. The 

 subject-matter has been brought up-to-date by revision and 

 additions. The price of the book remains 15, net. 



Erratum. — March 24, p. 104, col. i, line 36, for 

 " 9 grams " read " 6 grams." 



