OF ARTS AND SCIENCES. 403 



pounds, and having a cross-section of 16^ inches X 6 inches. The 

 load was in the centre, suspended from a yoke weighing 102 pounds. 



A micrometer was placed on tha beam, and the deflections were 

 measured as follows : — 



The modulus of elasticity corresponding to these deflections was 

 1,778,200 pounds per square inch. 



The beam broke by tension and longitudinal shear, at a load of 

 38,000 pounds. 



The corresponding calculated modulus of rupture, including the 

 weight of the beam, was 7,409 pounds per square inch. 



The maximum intensity of longitudinal shear was 287.9 pounds 

 per square inch. 



Torsion Testing Machine. — A two-inch Norway iron shaft, 6 feet 

 long between the holders, was twisted 16 turns without breaking. 

 This specimen, left over night with a twisting moment on it of 76,680 

 inch pounds, broke the next morning ; the maximum twisting moment 

 being 82,080 inch pounds. The shaft increased ^ of an inch in 

 diameter. 



Rope Testing Machine. — A Manila rope, 4^ inches in circum- 

 ference, 100 inches long, and held by two eye splices, broke at the 

 centre under a load of 15,000 pounds. The rope stretched 24 inches 

 before breaking. 



The other machines and appliances on exhibition were as fol- 

 lows : — 



The 150 horse-power triple expansion engine. 



The 16 horse-power Harris-Corliss engine. 



A rotary pump, a plunger pump, and a pulsometer. 



In the department of hydraulics was seen the discharge through a 

 circular orifice 1 inch in diameter in a thin plate. 



The Blake duplex pump, having a steam cylinder 16 inches in 

 diameter, a water cylinder, 10| inches in diameter and 12-inch 

 stroke, discharged water through three nozzles over a weir four feet 

 wide. 



The following paper was read by title : — 

 New Genera and Species of Laboulbeniaceae, with a Sj'iiop- 

 sis of the Known Species. By Roland Thaxter. 



