The 18th century
In the 200 years after the Statute of Monopolies, the patent system developed through the work of lawyers and judges in the courts without government regulation.
In the reign of Queen Anne, the law officers of the Crown established as a condition of grant that "the patentee must by an instrument in writing describe and ascertain the nature of the invention and the manner in which it is to be performed".
James Puckle's 1718 patent for a machine gun was one of the 1st to be required to provide a "specification". The famous patent of Arkwright for spinning machines became void for the lack of an adequate specification in 1785, after it had been in existence for 10 years.
Extensive litigation on Watt's 1796 patent for steam engines set out the important principle that valid patents could be granted for improvements in a known machine. It also established that a patent was possible for an idea or principle, even though the specification might be limited to bare statements of such improvements or principles, provided they come into effect, or were "clothed in practical application".