[WILLIAM, third EARL OF LOTHIAN, to whom this letter is addressed, was the eldest son of Robert, first Earl of Ancrum; and he acquired the title of Earl of Lothian by his marriage with Anne Ker, Countess of Lothian, by whom he succeeded to the estate and titles of Lothian in 1624. In 1638 he manifested great zeal for the Covenant. He was a member of the General Assembly which met at Glasgow that year, as elder for the Presbytery of Dalkeith. Hostilities having again commenced in 1640, his Lordship was in the Scottish army that invaded England, and defeated the Royalists at Newburn. In 1643 he was sent from Scotland by the Privy Council, with the approbation of Charles I. In 1644 he commanded, with the Marquis of Argyle, the forces sent against the Marquis of Montrose, whom he obliged to retreat, and then delivered up his commission to the Committee of Estates, who passed an act in approbation of his services. He was president of the Committee despatched by the Parliament to the King in December 1646, with their final propositions. He protested against the raising of an army in 1648 to rescue the King from the hands of the English, without receiving from His Majesty assurance that he would secure the religious liberties of his Scottish subjects,--an attempt which was called the "Engagement." But while resisting the arbitrary measures of his prince, he was of sincere and ardent loyalty. No sooner was it known that the Parliament of England intended to proceed against Charles I. before the High Court of Justice, than he and other commissioners were sent, in name of the kingdom of Scotland, to remonstrate against their proceedings in regard to the sacred person of the king. He took a solemn protest against their proceedings, for which he was put under arrest, sent with a guard to Gravesend, and thence to Scotland. On his return he received the thanks of Parliament for his conduct on this occasion; and, along with the Earl of Cassillis, was despatched to Breda in 1650 to invite King Charles to Scotland. His Lordship died in the year 1675. By Anne, Countess of Lothian, he had five sons and nine daughters.] (_ADVICE AS TO PUBLIC CONDUCT--EVERYTHING TO BE ENDURED FOR CHRIST._)