This section is from the book "Cassell's Cyclopaedia Of Mechanics", by Paul N. Hasluck. Also available from Amazon: Cassell's Cyclopaedia Of Mechanics.
It is customary in England to speak of all timber obtained from coniferous trees as " soft wood." Pitch pine is, of course, much harder than a number of the so-called "hard woods," but it would nevertheless be classified as a " soft wood." Much better is the system adopted in some parts of America, where four grades of hardness or softness are recognised -namely: " Very hard woods," " hard woods," " middling hard woods," and "soft woods." The names of a few familiar woods will illustrate its application: -
V. II. Woods. | Hard Woods. | M. H. Woods. | Soft Woods. |
Hickory. | Ash. | Pitch pine. | Pine and fir. |
Hard maple. | Black walnut. | Douglas fir. | Redwood. |
Locust. | Beech. | Larch. | Poplar. |
Best oak and elm. | Oak and elm. | Sweet gum. | Whitewood. |
Persimmon. | Lacewood. | Light birch. | Cypress. |
The classification is arrived at by the amount of power required to indent a square inch of the surface of the wood to a given depth.
 
Continue to: