Accounting theory and practice, Volume 2 (of 3) : a textbook for colleges and…

1. _Time Lapse._ There is no such thing as wear and tear on a patent

itself, but since the grant by the government is for a definitely prescribed term of years, as each of those years goes by there passes with it some portion of the value attaching to the exclusive enjoyment of the right for the prescribed period. In this country a mechanical patent is granted for a term of seventeen years, after which the patented device or process becomes common or public property. The period allowed for patents covering designs is three and one-half, seven, or fourteen years, depending on the application. Thus, simply through the lapse of time the value of the right diminishes.