126 
HUDLESTON AND DAVIS : EXCUESION. 
the sulphur waters at Harrogate is the absence, more or less 
complete, of sulphates. This peculiarity enables many of the 
Harrogate waters to act as carriers of salts of barium and strontium, 
which would otherwise be insoluble. In the " Alum Well," how- 
ever, a large quantity of sulphates exist. The probability is that 
this is due to the shallow origin of the spring, whose waters 
become oxidised, and this may account for the very considerable 
quantity of sulphates and the acid reaction so exceptional to the 
waters of this neighbourhood. Having spent some time at the 
springs, the company walked to Birk Crag, where they had an 
opportunity of looking from that very picturesque ridge of mill- 
stone grit over the wild and dreary scenery of Haverah Park, 
which consists entirely of the grits and shales of the millstone 
grit group. These rocks are noted for the purity of their waters. 
Oak Beck, which flows through Haverah Park, has been utilised 
for the purpose of supplying the town of Harrogate with pure 
water, just as the Washburn River has been adapted for supplying 
Leeds. The remainder of the evening was spent by the party in 
walking round by Harlow Carr and the back of Harlow Hill to 
Harrogate. They afterwards met at the Prospect Hotel and 
were very kindly welcomed to Harrogate by ]\[. Richard Carter, 
F.G.S., of Spring Bank, Harrog-ate, who, with Mr. Harry and other 
gentlemen, had done much to facilitate the success of the excursion. 
On Tuesday, the party left Harrogate for Knaresborough by 
an early train, and after a brief inspection of the old castle at the 
latter place, descended to the foot of the cliff on which what is 
left of the ancient pile stands. Here the unconformable junction 
of the magnesian limestone upon the millstone grit was pointed 
out by the president of the association and verified by the 
members. From this point they crossed the river for the purpose 
of visiting the Dropping Well, which is too well known to need 
description. Mr. Hudleston took occasion to explain the 
nature of the waters which flow over the rock. The stream 
supplying these waters springs out of the adjacent cliff, and 
