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POPULAR SCIENCE MONTHLY. 



workshop or has contrasted a first-class English shop where this is the 

 practice with an old-fashioned establishment where standardization is 

 hardly known, can have no hesitation on this question. It has its dis- 

 advantages, less is left to the originality of the workman and in con- 

 sequence they lose the power of adaptation to new circumstances and 

 conditions. The English mechanic is I believe greatly superior to the 

 German, but the scientific organization of the German shops enables 

 them to compete successfully with the English. 



In 1881 the German Association of Mechanics and Opticians was 

 formed, having for its aim the scientific, technical and commercial de- 

 velopment of instrument making. The society has its official organ, 

 the 'Zeitschrift fiir Instrumentenlvunde,' edited by one of the staff of 



Section of Iron aftek Varku's Treatments. 

 Specimen. 



1. Raised to 1000°. Worked and cooled slowly. Masses of carbide ground 

 work, bands of iron and carbide, pearlite structure. 



2. Raised to 850° and quickly cooled. Masses disappear. 



3. Raised to 850° and quenched in water. Arcicular structure. Martensite, 

 hard steel. 



4. Raised to 1050° and quenched in iced brine. Martensite and Austenite. 



5. Same cooled in liquid air to — 243. Much like martensite. 



6. Heated to near melting point, quenched suddenly burnt steel. 



7. Heated to 650° — annealed for a long time at this temperature and 

 slowly cooled, bands of carbide and pearlite. 



8. Any specimen except 6 heated to 850, worked and slowly cooled, giving 

 us the structure 1. 



Very marked changes might have been produced in 3 by annealing at 140°. 



