St. Agnes' Beacon was chosen as one of the principal western stations in the great Trigonometrical Survey of England. The position of the summit was then determined with extreme accuracy: Latitude 50° 18' 27", Longitude 5° 11' 55".7. In time 20 m. 47".7. Height above low water 621 feet. See the Philosophical Trans- actions for 1800, pp. 636 and 714.
St. Allen is situate in the hundred of Pow-dre-ham, id est, the hundred of the old ancient county or province town (viz. Lestwithell), for so it is called in the first Duke of Cornwall's charter 1336 now contracted and corrupted to Powder Cantred.
At the time of the Norman Conquest this district of St. Allen was taxed under the jurisdiction of Laner or Lanher, i.e. templer; so called, for that long before that time was extant upon that place a chapel or temple dedicated to God in the name of St. Martin of Tours, the memory of which is still preserved in the names of St. Martin's fields and woods, heretofore perhaps the indowments of that chapel or temple; this Laner is still the voke lands or capital messuage of the Bishop of Exeter's manor of Cargoll, whereunto it was annexed; in which place of Lanher (formerly a wood or forest of trees) the Bishops of Cornwall, and afterwards the Bishops of Exon, had one of their mansion or dwelling-houses for many ages,* till Bishop Voysey, tempore Henry VIII. leased those manors to Clement
* William of Worcester describes the Bishop's castle here as dilapidated temp. Edw.IV.