536 THE POPULAR SCIENCE MONTHLY. 



progress of those branches of natural knowledge the advancement of 

 which is the object of the vast collections gathered here. It has given 

 me much pleasure to learn that the memorial has received so much 

 support in foreign countries that it may be regarded as cosmopolitan 

 rather than as simply national ; while the fact that persons of every 

 condition of life have contributed to it affords remarkable evidence 

 of the popular interest in the discussion of scientific problems. A 

 memorial to which all nations and all classes of societv have con- 



m 



tributed can not be more fitly lodged than in our Museum, which, 

 though national, is open to all the world, and the resources of which 

 are at the disposal of every student of Nature, whatever his condition 

 or his country, who enters our doors. Nature. 



MODERN BRONZES.* 



By PEEEY F. NUESEY, C. E. 



WE had in the earlier ages of mankind a rough and a polished 

 stone age, a bronze age, and an age of iron, each distinguished 

 by the character of the material that was predominantly used by men 

 for their wsapons and tools, and have now added to those ages one of 

 steel. In a similar manner we are now entering upon a revival of the 

 bronze age, in which that substance in its varieties is to be put through 

 stages of improvement like those that iron and steel have undergone. 

 Many varieties of bronze have been produced within the last few years 

 that possess features strongly distinguishing them from the ancient 

 alloys, and some very remarkable qualities as compared with them, in 

 view of which they are frequently used in place of even iron and steel, 

 The bronzes of the ancients were composed of copper and tin, as is 

 also what is now regarded as bronze pure and simple, mixed in propor- 

 tions varying according to the purpose for which the compound is 

 intended. Other substances, however, are often added, without un- 

 classifying the product, which is still called bronze, provided copper 

 and tin are the chief constituents. Among these substances are zinc, 

 lead, phosphorus, manganese, silicium, iron, nickel, arsenic, antimony, 

 and sulphur. It is the addition of certain proportions of one or other 

 of such substances that constitutes the modern development of bronze 

 manufacture, and which has given us some of the most useful and at 

 the same time some of the most remarkable alloys known. These 

 comprise no fewer than eleven distinct products, all of which find 

 their uses in connection with the practice of engineering. They are : 

 phosphor-bronze, silicium-bronze, manganese-bronze, delta-metal, phos- 



* From a paper read before the Society of Engineers. 



