198 • REPORT— 1869. 



or watercourse about 30 inches high and 20 inches wide, the base of which, 

 at its junction with the Lake, is 8 inches below the highest level to which 

 the water could rise, and forms an asceusivc inclined plane, having an incli- 

 nation of 3°, and a length of about 3| feet. Beyond this point the inclina- 

 tion is in the opposite direction, and is very much more rapid. Beyond a dis- 

 tance of 18 feet its course has not been traced, but it seems to ramify in 

 various directions through the limestone. At the common vertex of the two 

 planes, a diaphragm of stalagmite about 9 inches high and something more 

 than 1 inch thick, extends quite across the tunnel from wall to waU, having 

 its upper edge sensibly horizontal, and leaving above it a free open passage 

 several inches high. It is obvious that whenever the water attained to this 

 level the Lake was full, and that the surplus flowed over the diaphragm of 

 stalagmite or natural weir. The fact that this regulated the maximum level of 

 the water is confirmed by a corresponding and strongly marked high-water 

 line along the entire boundary of the Lake. It is equally evident that unless 

 there had been some other means of escape, this height, once reached, would 

 have been permanent. During protracted droughts, however, the water has 

 been known to fall upwards of 2 feet below this level — a fact accounted for 

 by the slow oozing of the water through the Stalagmite. 



The entire circumference of the Lake, and especially the almost vertical 

 limestone wall on the south, is thickly studded with coralloidal tubercles of 

 arragonite of various sizes, extending from the high-water to the low-water 

 line. Indeed, they occur quite to the bottom of the Lake, but arc less 

 abundant than in the zone just mentioned. 



Many parts of the Cavern present phenomena and problems of interest to 

 the physicist as well as to the anthropologist and palaeontologist. Thus, to 

 go no further than the Lake, there are : — first, the facts that, at one period, 

 the water entering through the limestone roof formed a floor by precipi- 

 tating carbonate of lime, and that subsequently water, finding access through 

 the same channel and lodging on this very floor, was capable of dissolving it 

 and reducing it to a mere paste, apparently as calcareous as when it was in 

 the coherent condition ; second, that during the work of destruction, coral- 

 loidal masses of arragonite were formed on the naked limestone and Old 

 stalagmitic walls, but chiefly on the former ; third, that the water had slowly 

 increased the capacity of the Lake, by building a weir of stalagmite entirely 

 across the narrow tunnel which formed its principal outlet ; and, fourth, that 

 had time been allowed, this latter process must iiltimately have closed the 

 outlet and cntii'ely changed the drainage of the Lake. 



From the inscriptions in it, the number of persons who, from time to time, 

 visited the Crypt of Dates, must have been very great ; and every one of 

 them must have talten the same route, namely, along the entire length of 

 the Lake. The earliest known mention of the water is that by Polwhclc in 

 1797, in his ' History of Devonshire'*, when its condition appears to have 

 been identical with that in which the Committee found it. Assuming it to 

 have existed, and in the same state when the inscriptions were cut, the 

 scribes must have performed the journey by wading through it, by using a 

 float, by climbing along its almost precipitous northern wall, or by sAvim- 

 ming. The last is perhaps the most probable mode; but in cither case 

 they must have provided themselves with the requisite tools and with an 

 adequate supply of candles. In some cases the work appears to have con- 

 sumed a considerable amount of time. If, however, it is supposed that at 



<f The ' History of Devonshire,' 3 vols. 1797, vol. i. pp. .50, 51. 



