470 ANNALS NEW YORK ACADEMY GF SCIENCES 



The following program was then offered: 



Amadeus W. Grabau, Recapitulation as Viewed by a Paleontologist, 

 William M. Wheeler, Desert Ants. 



Homer D. House, The North American Species of the Genus 



Ipomoea. 



The papers read by Professors Grabau and Wheeler were illustrated 

 with lantern slides. 



The paper by Mr. House forms pages 181-263 of this volume. 

 The Section then adjourned. 



Roy W. Miner, 



Secretary. 



SECTION OF ASTRONOMY, PHYSICS AND CHEMISTRY. 



March 16, 1908. 



Section met at 8:15 P. M., Vice-President Hering presiding. 



The minutes of the last meeting of the Section were read and approved. 



The following program was then offered: 



William Campbell, Notes on Metallography applied to Engineering. 



Summary of Paper. 



Professor Campbell, in his paper, briefly reviewed the methods of pre- 

 paring specimens, development of structure, microscopic examination 

 and photographing the specimen. The structure of metals, ingotism and 

 grain structure, the effects of strain and of annealing were demonstrated, 

 and the constitution of alloys, mattes, speisses, etc., taken up. The carbon- 

 iron series, the graphite-austenite and cementite-austenite groups were 

 discussed and illustrated. Examples of structure were given; wrought 

 iron vs. low carbon steel, good and bad material; working and annealing 

 of medium carbon steel; rails and examples of their failure; steel tyres and 

 shelling out; the structure of hypereutectic steels and their change with heat 

 treatment; cast iron, gray, mottled, white, spiegeleisen ; cementation and 

 blister steel; malleableizing and the formation of temper carbon. 



The application of metallography to economic geology was shown by 



