The latter's son Henry (1746-1812) became 3rd duke, and in 1810 succeeded also, on the death of William Douglas, 4th duke of Queensberry, to that dukedom as well as its estates and other honours, according to the entail executed by his own great-grandfather, the 2nd duke of Queensberry, in 1706; he married the duke of Montagu's daughter, and was famous for his generosity and benefactions.
But, confining ourselves to what is here our special business, it is to be remarked that perhaps the heaviest blow dealt at these strange doctrines was that delivered by Rennie, who, in an edition of Montagu's Ornithological Dictionary (pp. xxxiii.-1v.), published in 1831 and again issued in 1833, attacked the Quinary System, and especially its application to ornithology by Vigors and Swainson, in a way that might perhaps have demolished it, had not the author mingled with his undoubtedly sound reason much that is foreign to any question with which a naturalist, as such, ought to deal - though that herein he was only following the example of one of his opponents, who had constantly treated the subject in like manner, is to be allowed.
Coming now to works on British birds only, the first of the present century that requires remark is Montagu's Ornithological Dictionary (2 vols.
Montagu's edition (17 vols., 1825-1834) is full but unscholarly.
For some years he lived in seclusion in Cornwall and occupied himself with theological studies, producing among other books The Arte of Happines (1619) and Testis Veritatis, a reply to Richard Montagu's Appello Caesarem.