All the political part of the English Constitution is fully understood, and distinctly stated in Blackstone and many other books, but the Ministerial part, the work of conducting the executive government, has rested so much on practice, on usage, on understanding, that there is no publication to which reference can be made for the explanation and description of it.

It is to be sought in debates, in protests, in letters, in memoirs, and wherever it can be picked up.

It seems to be stupid not to be able to say at once when two Secretaries of State were established; but Lord Melbourne is not able.

He apprehends that there was but one until the end of Queen Anne's reign, and that two were instituted by George I., probably because upon his frequent journeys to Hanover he wanted the Secretary of State with him, and at the same time it was necessary that there should be an officer of the same authority left at home to transact the domestic affairs.
_Prime Minister_ is a term belonging to the last century.

Lord Melbourne doubts its being to be found in English Parliamentary language previously.