ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 481 



Metallography, etc. 



Sorbitic Steel.* — H. C. Boynton finds that : (1) Furnace-cooling 

 of an under-saturated steel produces ferrite and pmrlite ; (2) air-cooling 

 of the same steel produces in samples of relatively small section, ferrite 

 and sorbite ; (3) the composition of sorbite depends upon the rate of 

 cooling ; (4) the carbon in sorbite is partially in the hardening condi- 

 tion, therefore all specimens subjected to " colour analysis " should be 

 previously annealed ; (5) air-cooling of a supersaturated steel greatly 

 increases the tensile strength and elastic limit, producing a structure 

 made up of pearlite containing an excess of cementite, and less free 

 cementite than under-furnace cooling. 



'&• 



Dudley, P. H. — Unit Fibre Stresses in the Base of Steel Bails. 



[Microscopical measurements and investigations of autographically-recorded 

 strains in the base of steel rails under moving locomotives, ca rs and trains, 

 to ascertain the apparent mean unit fibre-strains of the extreme fibres of 

 the metal, and some of the experimental laws of their distribution.] 



Journ. New York Micr, Soc, Annual of 1902, pp. 23-42. 



* Iron and Steel Mag., pp. 470-SO (SO photomicros.). 



Aug. 17th, 1904 



2 h 



