November 21, 1907] 



NATURE 



65 



occurs during the summer months. The second climate 

 consists of eight or nine rainy months, the percentage 

 being high in both summer and winter. The third and 

 best climate has a fairly even distribution of rainfall over 

 the whole )-ear. Reference should be made to the paper 

 in question for particulars as to the location of these 

 districts ; tables are given showing the monthly and annual 

 rainfall at all stations. 



The Journal of the Franklin Institute (vol. clxiv., No. 4) 

 contains an interesting report on the development of the 

 American locomotive as exemplified in the Baldwin Loco- 

 motive Works of Philadelphia. Founded in 183 1, the 

 works in 1832 completed one locomotive and employed 

 thirty men. In 1906 they built 2652 locomotives and 

 employed 17,432 men. Illustrations are given of seventeen 

 locomotives of dilTerent types made by the company, the 

 most interesting being the famous " Old Ironsides," com- 

 pleted and tried on November 23, 1832. In these early 

 days mechanics were few, and suitable tools could hardly 

 be obtained. Cylinders had to be bored with a chisel, 

 fastened in a block of wood, whilst blacksmiths who could 

 weld bars of iron exceeding i^-inch square were not to be 



■Old I 



had. Mathias Baldwin, therefore, had to do most of the 

 work himself in order to educate the men who assisted him 

 to fashion the necessary tools for the various processes. 



In view of the large number of ancient coins and medals 

 that have been preserved, it is surprising that so little 

 ;s known regarding the dies used. Some important con- 

 tributions to the knowledge of the subject are made by 

 Prof. C. Zenghelis in the Chemiker Zeitung of 

 November 9. In 1904 a die used for coinage was found 

 by a native at Tel El Athrib, Egypt, and was subsequently 

 presented to the museum at Athens. It dates from 430 B.C. 

 to 322 B.C., and is probably the only genuine antique die 

 preserved. It consists of bronze, and is 6 cm. high and 

 weighs 164-12 grams. On the base is engraved the owl 

 ■sxhibited by the Athenian tetradrachma pieces. The 

 surface was covered partly with a patina of copper 

 carbonate and partly with red cuprous oxide. On analysis 

 it was found that the die consisted of a bronze with 

 22-51 per cent, of tin and 69-85 per cent, of copper. The 

 remaining 764 per cent, undoubtedly consisted of oxygen, 

 as careful tests failed to show the presence of other 

 elements. Some cuprous oxide was mixed with the 

 material for analysis, and as in such alloys the tin oxidises 



more rapidly than the copper, it may safely be assumecl 

 that the mean composition of the alloy was 75 per cent, 

 of copper and 25 per cent, of tin. The strikingly large 

 proportion of tin in the alloy is quite unusual for bronzes 

 of that period, which usually contain 90 per cent, of 

 copper and 10 per cent, of tin, and the oldest bronzes of 

 all are still poorer in tin. The die affords remarkable 

 evidence of the metallurgical skill of the ancients. The 

 e.xtreme hardness required for a die was secured by in- 

 creasing the proportion of tin, whilst the requisite 

 malleability was secured by carefully using in the pre- 

 paration of the alloy the purest copper and tin, absolutely 

 free from lead or zinc, which would have made it softer, 

 and from antimony and arsenic, which would have made 

 it brittle. 



Madame Curie announces in the October number of 

 Le Radium the result of her re-determination of the atomic 

 weight of radium under conditions much more favourable 

 to accuracy than those which existed in 1902, when she 

 had only 9 centigrams of chloride of radium on w-hich to 

 work. The present determination has been made with 

 4 decigrams by the method used in the former case, and 

 gives as the result 226-2, if the atomic 

 weight of silver be taken as 107-8. 

 Madame Curie estimates the possible 

 error of the determination as less 

 than half a unit. 



The Munich Medizinische Wochen- 

 Sihrift for October 15 contains a de- 

 scription of an induction coil for 

 Rontgen-ray work, constructed by 

 Dr. J. Rosenthal, which is capable of 

 producing a photograph of a man s 

 thorax in two seconds with the tube 

 50 centimetres away. This certainly 

 brings us nearer to the much desired 

 Rontgen-ray kinematograph of the 

 action of important organs like the 

 heart, and it is to be hoped that Dr. 

 Rosenthal will succeed in still further 

 reducing the time of exposure. One 

 feature of his coil is the division of 

 both primary and secondary into 

 two or more parts, which can be 

 placed in series or in parallel with each other without 

 stopping the coil. 



The August Bulletin of the Bureau of Standards of 

 Washington contains an article on the melting points of 

 the elements of the iron group by Mr. G. H. Burgess. 

 The determinations were made by placing minute quanti- 

 ties (0-00 1 milligram) of the elements on a platinum strip 

 heated by the passage of an electric current through it. 

 The temperature of the strip was measured by an optical 

 pyrometer standardised by reference to the melting points 

 of zinc, 419° C. ; antimony, 630°-5 C. ; copper, 10S4'' C. ; 

 and platinum, 1753° C. The results are as follows : — 

 iron, 1505° C. ; chromium, 1489° C. ; cobalt, 1464° C. ; 

 nickel, 1435° C. ; manganese, 1207° C. 



The report of the director and librarian to the Warring- 

 ton Museum Committee for the year ending June 30 

 provides evidence that good work in the direction of 

 encouraging scientific observation is being done at 

 Warrington with the aid of the museum and its staff. 

 Among other arrangements made at the museum to 

 interest students and young pupils in natural history may 

 be mentioned the wild-flower table, which appears to be 

 visited regularly by students and by teachers preparing 



NO. 1986, VOL. 77] 



