270 • THE AMERICAN MONTHLY [December, 



ciently high elastic limits in the steel to keep the section from taking 

 permanent set under the loads or trains, it is necessary to have high 

 elastic limits in the metal to resist wear. vSteel of .35 to .40 carbon 

 has elastic limits in the head varying from 38,000 to 45,000 pounds per 

 square inch, and even then, in the thin-flanged rails, is liable to be 

 brittle. In steel like that shown in specimen No. 4 the elastic limits 

 range from 60,000 to 65,000 pounds in the head, and it is tough in 

 the sections in which it is used. In the 75-pound section, into which 

 several thousand tons have been rolled, the rails are exceptionally 

 tough, exceeding, so far as any records have been published, any tests 

 which have been made. In the 95-pound rails, into which many 

 thousand tons of high carbon metal have been rolled, they are much 

 tougher than was supposed possible to make such large sections. The 

 tendency of improvement in quality of steel is now the production of a 

 fine texture having high elastic limits and considerable percentage of 

 elongation before the full limit of tensile strength is reached. Speci- 

 men No. 5 shows the end of a tensile specimen of 53,470 pounds elas- 

 tic limit and 23 per cent, of elongation, the fracture fine and silky, 

 showing at once that it was a tough piece of metal. No evidence of 

 coarse crystalization on the interior of the specimen is to be seen, 

 portions of the matrix penetrating and pulling out from the interior of 

 all the crystals. This steel has been worked to make a fine texture. 

 Specimen No. 6 is from the side of specimen No. 5, and shows on the 

 exterior a tendency to separation on the outside surface of the original- 

 large crystals as soon as the steel has passed the elastic limits. On the 

 interior, each crystal being surrounded, greater flow or distortion takes 

 place before separation. This specimen will also serve to better illus- 

 trate my remarks about the necessity of high elastic limits in surface of 

 the rails to resist wear. 



Reference List of Original Articles Relative to Diatoms Pub- 

 lished in the American Monthly Microscopical Journal. — Vol- 

 umes I-XII. 



By ROBERT W. SMILEY, 



WASHINGTON, D. C. 



[Compiled by request of Monsieur J. Tempore, Editor of Le Diatomiste.\ 



Volume I. 1880. 



Procuring and Cleaning Diatoms. By K. M. Cunningham. April, 

 p. 66. 



About Diatoms. (Editorial.) May, p. 84. 



Direction for Cleaning Diatoms. (Editorial.) June, p. 107, and Au- 

 gust, p. 146. 



About Diatoms. By Chas. Stodder. June, p. 113. 



Synopsis of Diatoms. (Editorial.) July, p. 135. 



Parasites on Diatoms. (Editorial.) August, p. 151. 



About Diatoms. By C. M. Vorce. August, p. 158. 



Movement of Diatoms. (Editorial.) October, p. 182. 



Synopsis of Diatoms in Belgium. (Editorial.) October, p. 198. 



Cleaning Diatoms by Mr. G. C. Morris' Method. By A. L. Wood- 

 ward. November, p. 215. 



