Heights qf the principal Hills qf Swaledale, Yorkshire. 3 



claim on the survey than its celebrity as an extensive and most 

 productive mining field. (Having finished the signal on the 

 Hoove in the early part of the day, it was intended to have 

 descended the ridge and marked two or more conspicuous 

 points for measurement; a design unexpectedly frustrated by 

 the occurrence of a local storm of wind and dense mist.) 

 Lastly, there appears, according to the shading of the maps, a 

 round eminence, marked as Byer's Hill, situated considerably 

 to the east of the Hurst Moor. From the station on Pinch 

 Yate, which affords a commanding view of that part of the 

 dale, the hill, probably from its insignificancy, could not be 

 distinguished. 



Conical piles of large sods, constructed of the usual dimen- 

 sions, served for signals on Hugh Seat, Nine Standards, 

 Keasdon, East Stonesdale Moor, Rogan's Seat, Blake Hill, 

 Brownsey, Great Pinch Yate, the Hoove, and Gibbon Hill; 

 smaller piles of stone marking the summits of the Tail Brigg, 

 Calvey, Harker, and Grinton Grits. Of these hills the highest 

 point was most carefully determined by the (repaired) twelve- 

 inch telescopic-level. About half a mile S.S.W. of the signal 

 on the Nine Standards is an eminence so nearly of equal alti- 

 tude, that it was deemed necessary to repair there in order to 

 confirm by reciprocal observation the correctness of the adjust- 

 ments of the level. With a view to expedite the completion of 

 the signals required, as well as to guard against their future 

 demolition, parties of miners were hired as frequently as pos- 

 sible to procure and pile the materials on the exact spot 

 marked out. At Dod End and Satron Hangers it was una- 

 voidably necessary to entrust to them, not only the erection of 

 the signals, but also the fixing of their sites; a task which the 

 extensive practice of the miners in forming watercourses would 

 render them competent to execute with the requisite accuracy. 

 That these signals were properly placed was verified by apply- 

 ing to them the test of the horizontal wire of the horizon-sector 

 from several stations of about the same altitude, in which case 

 the true and apparent (or perspective) summits would sensibly 

 coincide in level. The highest point of Robincross Hill, at a 

 right-angled turn of the wall crossing its ridge, was marked by 

 placing on the wall an adequate number of loose stones. Hol- 

 gate Pasture was not visited; but from its round figure, incon- 

 siderable size, and remote distance, it scarcely required a signal. 



The difficulty of correctly bisecting a signal by the vertical 

 wire of the telescope of the theodolite, hitherto effected by the 

 tedious perfecting of an approximate bisection, was finally sur- 

 mounted by the following mode of operation. Commencing at 

 once with the wire placed at an angle of some minutes to the 



B2 left 



