36 On certain Rocks supposed to move. 



pass of nearly a mile, no such eminences appear. But I 

 shall perhaps throw some light upon this, when I come to 

 those rocks whicli move. The third argument which might 

 be adduced, is the situation of the rocks. This neck of 

 land (I mean that part of it which is not alluvial,) is nearly 

 of the same width throughout. Were not some of the rocks 

 of which it is composed, of such a size, we should undoubt- 

 edly be led to suppose it an artificial causeway. Does not 

 this equality, or uniformity of width, favor my supposition .'' 



As to the moving rocks, I made such observations as my 

 short stay in the place would permit. This phenomenon 

 was known to the first inhabitants of the town. Its proba- 

 bility was suggested by their own observation, and its truth 

 established by actual measurements. From the gentleman 

 with whom I visited the spot, I obtained the following meas- 

 urement. Its correctness may be implicitly relied on. 



Sept. 1819. The distance from the largest rock to a cer- 

 tain birch tree on the shore, was 15 rods 39 links. 



Feb. 13,1821. The distance of the same rock to the same 

 tree, was 12 rods 37i links. Subtracting 12 — 37 from 

 15 — 39, leaves 3 rods 2 links, which this rock moved iu 

 less than eighteen months. The same gentleman measured 

 it each time, and used the same chain in both. 



Twelve* years ago it moved but five feet in a year. Its 

 motion is therefore accelerated as it approaches the shore. 

 I have spoken particularly of this rock, because it is the on- 

 ly one whose exact progress has been ascertained. All the 

 stones however, in this part of the lake, move, from the lar- 

 gest to the smallest, and leave a track or trench behind 

 them,of greater or less magnitude, in proportion to the size of 

 the stone. The largest rock (and it probably weighs forty 

 or fifty tons,) has ploughed up the sand and gravel before it 



*The island marked E is about three quarters of a mile from the shore. It 

 is composed of mica slate, lying on a bed of limestone ; large masses of the 

 latter lie on the shore of the island. You will see by a simple calculation, 

 that, at the present rate of moving, they will reach the opposite shore in less 

 than a hundred years. That those masses composing the foundation of 

 the road cams from thence, I will not pretend to say. 



The mi'ieralf I observed in Salisbury are the following: — Tremolite ra- 

 diated, stellated with fibre? nearly two feet long; Garnets in abundance; 

 Staurotide; black and white Mica; Jasper; Sulphat of , Iron ; Alumine; 

 Iron ore — all varieties ; generally the brown Iron stone of Werner; Dolo- 

 mite; Carbonate of Lime; Mica slate ; Clay; Ochres, &c. of various kinds. 

 Some Copper, in the Iron-ore lately found. 



