...proviso was inserted in all letters patent requiring the grantee particularly to describe and ascertain the nature of his invention and in what manner the same was to be performed or manufactured. Thus originated the specification of letters patent. On May, 25, 1624, during the...

...proviso, and of the said letters patent, particularly describe and ascertain the nature of the said invention, and in what manner the same was to be performed, by an instrument in writing under his hand and seal ; and that he caused the same to be inrolled in the...

...proviso, he should deliver to the Lord Chancellor, within 15 months from the date of the letters-patent, a particular description or specification of the nature...his invention, and in what manner the same was to be performedj by writing under his hand and seal ; which specification, together with an affidavit made...