In 1811 Barnabas Langdon and William Mowry received a patent for a stave jointer. In 1835 Langdon patented a lath-making machine. In 1838, he received two patents for planing machines—the former for planks and clapboards, and the latter for shingles.
Langdon tried to get his two planing machine patents reissued once they had almost expired. Reissues are granted when the original patent specification is defective in some way, but nothing can be introduced that was not in any of the original model, drawings, or specifications. Langdon's original drawings and specifications clearly showed a stationary bar in front of the first cutter, but the application for reissue showed a spring-loaded yielding bar. Langdon testified that his original model did not have a yielding bar, though he "did know the importance of it." At some point, having apparently learned that his model was lost in the 1836 fire, he changed his testimony and claimed that the model did have a yielding bar. The patent examiner firmly rejected Langdon's request.
Information Sources
- Articles in 1851 Scientific American.