limit for a short-time load. This may be illustrated to some extent by a test like that of the three oak specimens shown in Fig. 4 with diagrams in Fig. 16. This, of course, cannot be carried out before the class on account of the long time required, but, if explained in object and plan, and kept going during the week, will arouse much interest and discussion. The underlying motive in all this testing in connection with the class

this Shartering in pur in 827 Wet

FIG. 14.

room work should be to arouse the student, to make him see facts and relations clearly, to make him think. To this end also some simple problems in designing may be introduced from time to time, illustrating the practical use to be made of these test results. For instance, following the timber tests, the design of a low railroad trestle proves both interesting and instructive, requir

RESULTS OF TESTS OF WHITE PINE-SERIES B-PROPERTIES OF

ing as it does a discussion of factors of safety and allowances to be made for knots, seasoning checks and decay.

Now taking up the different materials as cast iron,