Heights of the principal Hills of Wensleydale, Yorkshire. 351 



On commencing the survey, it was discovered that the twelve- 

 inch telescopic-level, recently fitted up with extremely^ fine 

 cross-wires, would not, from some imperfection in the screws 

 of the stop, retain its adjustments. The extreme summit of 

 the hill was, therefore, of necessity estimated by the eye alone 

 previous to the erection of the signal. That no material error 

 had been committed in the few doubtful cases which occurred, 

 was subsequently confirmed ; not only where the theodolite was 

 erected, from actual levelling around the signal by means of 

 that instrument, but also by remarking in the course of the 

 observations that the hoi'izontal wire of the telescope, when 

 pointed at the base of the signal on any of the distant hills of 

 about the same altitude as the station, did not dip sensibly be- 

 low any other part of that hill. The signal on Bakestone 

 Edge was found to be rather lower than a point more to the 

 north ; but the latter was evidently within the boundary of 

 Swaledale, and consequently out of the limits of the survey. 

 Viewed from the signal on the Stake Fell, a peat hillock nearly 

 two miles to the south-east was suspected to be quite as high ; 

 but it was noted, on repairing there, that a straight line drawn 

 from the hillock through the base of the signal, would touch a 

 point of Water Crag very little below the level of its summit. 

 Now as Water Crag has been determined to be about 350 

 feet higher than Stake Fell, it proves that the signal was placed 

 considerably above the level of the hillock. 



With regard to the structure of the signals, piles or pikes 

 of stone were found on the loftiest points of Water Crag, Shun- 

 nor Fell, and Great Whernside, marking the precise site 

 of signals of the Ordnance Survey. On Settronside, a well- 

 built tower fiiteen feet high and nine feet in diameter at the 

 base, recently erected at a distance of forty-five yards to the 

 north-east of the extreme summit of the fell, served as an ex- 

 cellent signal. On Lovely Seat there stands a lofty boundary 

 pike situated some little below the level, but within a few yards 

 of the highest point of the hill ; to which point, in lieu of the 

 base of the pike, on the measurement of the vertical angles the 

 telescope was invariably directed. Stone towers about eight 

 feet high, ami nearly as much in diameter, marked the summits 

 of High Fleak, Bakestone Edge, and Swarth Fell ; the latter 

 being erected on a large rock. The signals at Addlebrough 

 and Rover Crag were of a similar desci'ijition, but much in- 

 ferior in dimensions. On the wall crossing the summit of 

 Whitfield Hill were heaped, immediately over the most ele- 

 vated point of ground, a number of loose stones; but this 

 signal, from its iiisuflicienl dimensions, could seklom be dis- 

 tinctly seen through the telescope of the theodolite. Tlie 



other 



