ABSTRACT OF PROCEEDINGS. XXV. 



the load producing fracture ; the determination of the 

 true form of the stress curve from the actual strain curve 

 in a plain and in a reinforced concrete beam. 



c. The safe working stresses and the fundamental 

 equations recommended for the design of reinforced con- 

 crete structure. 



d. The adhesion of cement mortar and concrete to the 

 steel reinforcement was determined by pulling out speci- 

 ally prepared bars of Bessemer steel from prisms 12 inches 

 long x 4 inches x 4 inches cross section, by means of a 

 testing machine. 



i. With steel bars having the natural 



skin on, after 45 days hardened 



in air 198 lb per sq. inch 



ii. With the skin removed and the 



bars polished, after 45 days 



hardened in air 125 ,, ,, „ 



iii. With the skin removed as in ii., 



but hardened in water, after 45 



days 185 „ „ „ 



b. The experimental determination of the neutral axis 

 in a plain and in a reinforced concrete beam, also the 

 curves of strain for loads increasing from zero to that 

 necessary to produce fracture, was made in a special form 

 of Buckton testing machine, with two hydraulic presses 

 for applying the loads at the ends of the beams tested. 

 Ten beams 72 inches long were tested on supports 40 inches 

 centre to centre, with two overhanging portions each 16 

 inches long. The apparatus for measuring the lengthening 

 and shortening of the beam between the supports over a 

 length of 40 inches, consisted of eight Martens' mirror 

 extensometers, with a corresponding number of scales and 

 telescopes arranged at different positions in the depth of 

 the beam. The extreme fibre strains were determined by 



