10 ROYAL SOCIETY OF CANADA 
Table showing mean strains in a 5.9-in. X 4.94-in. white pine beam, 
under two different systems of loading. 
Compressive strains + 
Tensile _ 
Extensometers 1.3-in. c. to c. 
The strains are, in each case, the means of four observations, 
TOTAL STRAINS AT DIFFERENT POSITIONS OF EXTENSOMETERS, IN MILLIONTHS 
OF AN INCH. 
Load. 1 IL. III. IV. V. 
000 000000 000000 000000 000000 000000 
£ SOON EE MOD eo SOON MEET bay 02 ME 
3 600; “4 200911 0062 AE 000. = MTL NT EG 
Z 900' +, 2869 + 1386 = 195 “= 1705 |= 9440 
8 1200" 8640 NE TOTS 192) 05 221) da 
1500 | qi -4B67 |, “-p9.2199 S248 0 06 RES 
= 000 000000 000000 000000 000000 000000 
£ 400 oder 472 NT ee 00756 Uta) 
Ë g 800 221 070 Way abe eee 
Ee 1200.) S250) Mo TON =| 1970) sees 
3 1600 M aa7t |. Loo7t” Wer es7 =" onde ee Paore 
= 2000 + 5306 + 2579 - 255 — 3059 — 595 
From the above results diagrams 4 to 7 have been prepared, and 
seem to justify the inferences: 
(1) That when a beam is loaded at the centre, the position of the 
neutral surface, under increasing loads remains practically unchanged 
and is a little nearer the compression than the tension side. — 
(2) That when loads are concentrated at points equidistant from 
the centre, the neutral surface, under the smaller loads, is at some 
considerable distance from the mid depth on the compression side. 
This distance diminishes as the load increases, and under the heaviest 
loads the neutral surface seems to have gradually returned to nearly 
the same position as when the beam was loaded at the centre. 

