491. Distinction between discovery and invention.

The difference between discovery and invention has been often emphasised1, and it has been held that a patent cannot be obtained for a discovery in the strict sense2. If, however, the patented article or process has not actually been anticipated3, so that the effect of the claims is not to prevent anything being done which has been done or proposed previously, the discovery which led to the patentee's devising a process or apparatus may supply the necessary element of invention required to support a patent