_Marking and sketching_: The butt end of the beam is marked _A_ and the top end _B_. While facing _A_, the top side is marked _a_, the right hand _b_, the bottom _c_, the left hand _d_. Sketches are made of each side and end, showing (1) size, location, and condition of knots, checks, splits, and other defects; (2) irregularities of grain; (3) distribution of heartwood and sapwood; and on the ends: (4) the location of the pith and the arrangement of the growth rings, (5) number of rings per inch, and (6) the proportion of late wood. The number of rings per inch and the proportion of late wood should always be determined along a radius or a line normal to the rings. The average number of rings per inch is the total number of rings divided by the length of the line crossing them. The proportion of late wood is equal to the sum of the widths of the late wood crossed by the line, divided by the length of the line. Rings per inch should be to the nearest 0.1; late wood to the nearest 0.1 per cent. Since in large beams a great variation in rate of growth and relative amount of late wood is likely in different parts of the section, it is advisable to consider the cross section in three volumes, namely, the upper and lower quarters and the middle half. The determination should be made upon each volume separately, and the average for the entire cross section obtained from these results. At the conclusion of the test the failure, as it appears on each surface, is traced on the sketches, with the failures numbered in the order of their occurrence. If the beam is subsequently cut up and used for other tests an additional sketch may be desirable to show the location of each piece. _Adjusting specimen in machine_: The beam is placed in the machine with the side marked _a_ on top, and with the ends projecting equally beyond the supports. In order to prevent crushing of the fibre at the points where the stress is applied it is necessary to use bearing blocks of maple or other hard wood with a convex surface in contact with the beam. Roller bearings should be placed between the bearing blocks and the knife edges of the crosshead to allow for the shortening due to flexure. (See Fig. 29.) Third-point loading is used, that is, the load is applied at two points one-third the span of the beam apart. (See Fig. 30.) This affords a uniform bending moment throughout the central third of the beam. [Illustration: FIG. 30.--Two methods of loading a beam, namely, third-point loading (upper), and centre loading (lower).]