Section 4899. Every person who purchases of the inventor, or discoverer, or with his knowledge and consent constructs any newly invented or discovered machine, or other patentable article, prior to the application by the inventor or discoverer for a patent, or who sells or uses one so constructed, shall have the right to use and vend to others to be used, the specific thing so made or purchased, without liability therefor.

This section does not grant the right to an invention any further than to the extent of the machines constructed prior to the application for the patent.34