ME. E. WILSON ON- THE DURHAM SALT-DISTRICT. 763 



discovery at Middlesborough an attempt was made to sink a shaft 

 in order to mine the rock-salt, but the influx of water was so con- 

 siderable that the undertaking was for the time abandoned, and for 

 nearly twelve years nothing further was heard about Middlesborough 

 salt *. 



In the year 1874 Messrs. Bell Bros, engaged the " Diamond Rock 

 Boring Company " to put down an exploring hole t, close to their 

 ironworks at Port Clarence on the north bank of the Tees, about 

 three quarters of a mile (1314 yards) nearly due north of the 

 Middlesborough boring, and after nearly two years' work, the bed of 

 rock-salt, Co feet in thickness, was reached at a depth of 1127 feet. 

 In order to prove the character of the strata beneath the rock-salt, 

 this borehole was continued for 150 feet below the thick bed of 

 rock-salt, or to 1342 feet t from the surface, and at this depth strata 

 were met with which were identified (erroneously, I believe, see 

 p. 770) as the Magnesian Limestone of Durham §. 



Having proved the salt-bed, Messrs. Bell sank a well at the 

 Clarence Ironworks, nearly a mile (1680 yards) due north of the 

 place where it was first discovered at Middlesborough, and at this 

 point found it at a depth of 1043 feet, having a thickness of 65 feet. 

 Subsequently they put down a second hole about half a mile (830 

 yards) E.N.E. from their first well, and again found the salt-bed, 

 rather thicker than before, at a depth of 1129 feet. Messrs. Bell 

 Bros, were the first who succeeded in working the salt-bed in the 

 Durham district, by a process which will be hereafter referred to. 



The success of this enterprising firm soon led other competitors 

 into the field. Most of the subsequent explorations have proved 

 the rock-salt to be present in good thickness ; but in two or three 



* " On the Manufaeture of Salt near Miclcllesbrough," bj^ Sir Lowthian Bell, 

 Bart., F.R.S., M.Iust.C.E., ' Proc. Inst. Civil Engineers,' vol. xc. 1886-87, part 

 iv. p. 131 et seq. 



t Loc. cit. See Appendix, p. 779, for details of this boring. 

 I Two analyses of this limestone given by Sir Lowthian Bell, in his valuable 

 paper already quoted, yielded the following results : — 



feet. feet. 



" Depth from under-surface of the salt 154 193 



Carbonate of Hme 54-71 94-48 



„ magnesia 41-18 2-98 



iron 0-81 78 



Silica 200 120 



Bitumen 0-22 036 



Moisture 1-08 0*20 



100-00 100-00" 



There are some slight discrepancies here. In the sections to Sir L. Bell's 

 paper (pi. 3. fig. 3) the total depth of the boring is given as 1355 feet, and the 

 beds of " limestone and much gas " and "grey limestone and gypsiim " described 

 in that section, and from which the above analyses appear to have been taken, 

 lie at depths of from 56 to 133 below the zmder surfnce of the rock-salt, and 

 therefore could not have come from depths of 154 and 193 feet below that bad. 

 Probably " depth from upper surface of the salt " is here meant. 



§ Loc. cit. p. 133. 



