STRENGTH AND ELASTICITY OF REINFORCED CONCRETE. 153 



and two were plain. The results obtained are recorded 

 in Tables V. a. V. b., and in the diagrams Figs. V. a. and 

 V. b. These tests are a continuation of the work described 

 in a previous paper, 1 their chief interest being the age at 

 which they were tested, as they show the same general 

 characteristics as similar beams described in the paper 

 referred to, but which were tested at a lesser age. 



Experiments were also made on concrete beams, con- 

 sisting of 1 of cement, 2 of sand, and 3 of broken basalt f 

 inch gauge. These beams were 10 by 10 inches in cross 

 section, and were tested, except in the case of No. 1, on 

 a span of 120 inches. Beams Nos. 1, 2, 3 and 4, were re- 

 inforced on the tension side by three steel rods |- inch in 

 diameter, beams Nos. 7 and 8 were not reinforced. In the 

 testing of these beams it was attempted to measure the 

 strains produced by the various loads applied, in causing 

 deflection, in shortening it on the compression side at the 

 extreme fibres, and at positions 1-j- inch from the top and 

 bottom of the beam. The apparatus used consisted of the 

 Martens' mirror extensometers, used with four telescopes 

 and scales, also some accurately made sectors and dials. 

 The method of applying these instruments to the beam is 

 illustrated in Pigs. 7, 8, and 9, and the results obtained 

 are recorded in the following diagrams. 



Fig. VI. a. shows the loads and the extensions produced 

 by them between the centre of the beam and 20 inches on 

 either side of the centre. The extensions are measured 

 1 \ inch from the top of the beam, and at the top of the 

 beam, which was the extreme fibre on the tension side. 

 Fig. VI. b. shows the loads and corresponding shortenings 

 measured in a similar manner. Fig. VI. c. shows the loads 

 and the extensions measured at the top of the beam 

 (extreme fibre), and Fig. VI. d. shows the loads and corres- 



1 Journ. Roy. Soc. N.S.Wales, Vol. xxxvi., 1902, p. 298. 



