An official website of the United States government
Here's how you know
Official websites use .gov
A.gov website belongs to an official government
organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
| Authors: | Forest Products Laboratory |
| Year: | 1949 |
| Type: | Technical Note |
| Station: | Forest Products Laboratory |
| Source: | Technical note ; 217 |