 [N] ew manufacture must have seven properties. First, it must be for twenty-one years or under. Secondly, it must be granted to the first and true inventor. Thirdly, it must be of such manufactures, which any other at the making of such letters patent did not use ... Fourthly, the privilege must not be contrary to law ... Fifthly, nor mischievous to the state, by raising the prices of commodities at home. In every such new manufacture that deserves a privilege, there must be urgens necessitas et evidens utilitas. Sixthly, nor to the hurt of trade ... Seventhly, nor generally inconvenient.
