$ 
486 The Philippine Journal of Science 1921 
any specific case. Ordinarily not only will native wood found 
in the local market serve the purpose of the engineer, but it can 
be secured in better grades and at lower prices. In such cases 
the local material will very likely be used, provided reliable in- 
formation regarding its properties is available. Without such 
information, however, the tendency of the builder is to use im- 
ported wood whose mechanical properties^ are known to him. 
SMALL CLEAR SPECIMENS USED 
Small clear specimens are used in the tests in order that con- 
sideration of the influence of defects may be eliminated from 
calculations to determine the relation between strength and den- 
sity, moisture, locality of growth, etc. These various relations 
are not referred to in a specific way in the present publication, 
on account of the very small number of timbers available for 
tests. The specimens are 2 by 2 inches in cross section. Bend- 
ing specimens are 30 inches long; others shorter, depending on 
the kind of test made. 
The materials first tested came from the local market, and the 
rest, which were botanically determined, came from the Bureau 
of Forestry. Mr. E. E. Schneider, wood expert, Philippine Bu- 
reau of Forestry, kindly furnished the descriptions of the woods. 
TENSILE STRENGTH 
Timber used in construction is practically never subjected to 
pure tensile stress, for the reason that the end connections can- 
not be so devised that they do not involve either shear along 
the grain or compression perpendicular to the grain. The 
resistance offered by any timber to compression across the 
grain, or shearing stress parallel with the grain, never amounts 
to more than a small fraction of the tensile strength, as shown 
by the tests. Therefore, the tensile strength of timber is not an 
important property except in so far as the tensile strength is 
involved in all cases of transverse loading. For reasons of econ- 
omy in the erection of structures, iron and steel should be 
used in parts that are to be subjected to purely tensile stress. 
TANGILE 
Tangile [ Shorea polysperma (Blanco) Merr.] is a very wide- 
ly distributed and fairly abundant species. Fox worthy 2 esti- 
mates that it makes up about 7 per cent of the volume of the 
forests of the Islands. Botanical collections of tangile are re~ 
2 Philippine Dipterocarpaceae, II, Philip. Joum. Sci. § C 13 (1918) 165. 
