Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. One of the principal objectives of laboratory investigations is to determine values per unit area for the various strength proper ties of wood. These, however, because of the complex structure of wood, cannot have a constant value that will be exactly repeated in each test, even though no error be made. The most that can be accomplished is to find average values, the amount of variation above and below this average, and the laws that govern the variation.