results, the load has been assumed as concentrated at the center of the
beam. While it is true that the load was spread over a length of about
12 in., due to the width of the head of the machine and the plate
between it and the beam tested, it is also true that there were
irregularities, such as bolt-holes and, in some cases, abrasions due to
wear, that could not well be taken into account. Hence, it was deemed
sufficiently accurate to consider the load as concentrated. Besides the
horizontal bolt-holes, shown in the photographs, there were vertical
bolt-holes, at intervals in all the beams. The latter were 7/8 in. in
diameter, and in every case they were sufficiently removed from the
center of the length of the beam to allow the maximum moment at the
reduced section to be relatively less than that at the center of the
beam. For this reason, no correction was made for these holes. The
broken beams often showed that rupture started at, or was influenced by,
some of the holes, especially the horizontal ones.

While some of the heavy oils of a tarry consistency remained, they were
only to be found in the sappy portions of the long-leaf pine and in the
loblolly (Specimens II and IV). Exposure in a semi-tropical climate for
26 years had resulted in the removal of the more volatile portions of
the creosote oil. The penetration of the oil into the sap wood seemed to
be perfect, while in the loblolly it varied from a fraction of an inch
to 1-1/2 in. In the heart wood there was very little penetration across
the grain. The timber had been framed and the holes bored before
treatment. The penetration of the creosote along the grain from the
holes was often from 4 to 6 in.

Circular 39 of the Forest Service, U. S. Department of Agriculture,
entitled "Experiments on the Strength of Treated Timber," gives the
results of a great many tests of creosoted ties, principally loblolly