Patent Model, Mechanical Chair

This rare surviving model of an adjustable chair was part of the process to secure a patent in the United States in the late nineteenth century. There were two types of patents: utility, or technical, patents and design patents. The later was for two-dimensional inventions such as carpet and textile designs. The former, more common type was for all other inventions, both mechanical and scientific. The patent process required three elements: a scaled, fully functional model not more than one foot square, detailed line drawings, and a letter describing the innovation. Inventors usually hired a lawyer to help secure the patent, and the lawyer in turn had contacts with professional model makers and draftsmen to render the detailed models and drawings. Once approved, the patent was good for up to seventeen years.

The government then placed the patent models on display in the United States Patent Office Building in Washington, D.C.
The requirement for the model was abandoned in the late 1880s, and the government sold off the vast majority of the models in the early twentieth century, thereby losing a visual history of late nineteenth-century technology.