Blackadder, an estate and a river in Berwickshire. The estate is in Edrom parish, and belongs to Sir George A. F. Houston-Boswall, second Bart. since 1836 (b. 1809; suc. 1842). The mansion on it stands on the right bank of the river, 2 miles SS W of Chirnside, and has a cast-iron conservatory, in the form of a Gothic chapel, erected at a cost of several thousand pounds. A mineral well is on the estate, in a ravine near the river, not far from its influx into the Whitadder.-The river Blackadder rises in several head-streams among the Lammermuirs, in Westruther parish, at altitudes of from 1000 to 1200 feet above sea-level. Making a confluence of its head-streams in the NW of Greenlaw parish, it thence runs 6 miles south-eastward to Greenlaw town, thence north-eastward through Greenlaw, Fogo, and Edrom parishes to the Whitadder in the vicinity of Allanton, 1½ mile SW of Chirnside. Its length of course is some 20 miles; and its velocity, from the confluence of its two head-streams onward, has numerous alternations of calm pool and rapid current. Its waters containgood tront, but in some parts are strictly preserved. The name Blackadder is probably a corruption of Blackwater; seems to have been derived from a darkish tinge of the river, occasioned by peatiness of the soil in the upper reaches; and is usually pronounced and sometimes written Blackwater.—Ord. Sur., shs. 25, 26, 34, 1863-64.

(F.H. Groome, Ordnance Gazetteer of Scotland (1882-4); © 2004 Gazetteer for Scotland)