3^ PHILOSOPHICAL TRANSACTIONS. [aNNO 17 18. 



General Scholium. — Should the numbers, which here and there are added to 

 the symbols, appear less accurate to any one, he may easily, by finding by expe- 

 riments numbers that approach nearer the truth, correct the above-mentioned 

 examples of motion, either by the help of the propositions themselves, or their 

 corollaries. 



An Account of the Sinking of three Oaks into the Ground, at Manington, 

 Norfolk. By Peter Le Neve, Esq. Norroy King at Arms, and F. R. S. 

 N° 355, p. 766. 



On Tuesday, July '23, 1717, near the seat of Sir Charles Potts, Bart, at 

 Manington, nearly midway between Holt and Aylsham, and about 7 miles 

 from the coast near Cromer, an oak sunk, with the roots and ground about it, 

 and not long after, at about 40 yards distance, two other oaks sunk in the same 

 manner into a much larger pit, about 33 feet diameter, but the former not 

 quite 1 8. These, as they sunk, fell across, so that obstructing each other, the 

 roots of only one of them reach the bottom, whereas the first stands perpen- 

 dicular. 



When the first tree sunk it was observed, that the water boiled up in the 

 hole, but on the sinking of the greater pit, it drained off into it from the 

 former, which now continues dry. Its depth to the firm bottom is Q feet 3 

 inches, and the tree that stands upright in it, is 3 feet 8 inches in girt, and its 

 trunk about 18 feet long, half of which is now within the pit. In the bottom 

 of the greater pit, there is a pool of water about 8 feet diameter, its surface 11 

 feet 3 inches below the ground, and the trees in this pit are much of the same 

 length with the others, but somewhat smaller, the one being in girt 3 feet 5 

 inches, and other only 2 feet Q inches. 



The soil on which these trees grew is gravelly, but the bottom is a quicksand 

 over a clay, on which there are springs, that feed large ponds adjoining to Sir 

 Charles Potts's house, at about a quarter of a mile from these pits. 



The nature of the soil seems to afford a reasonable conjecture at the cause of 

 this odd accident: for the springs running over the clay at the bottom of a bed 

 of very fine sand, such as quicksands usually are, may reasonably be supposed 

 in many ages to have washed away the sand, and thus to have excavated a kind 

 of subterraneous lake, over which these trees grew; and the force of the winds 

 on their leaves and branches agitating their roots, may well have loosened the 

 sand under them, and occasioned it to fall in, more frequently than elsewhere; 

 whence in time the thin bed of gravel only being left, it might become unable 

 to support its own weight, and that of the trees it bore. That this is not a 

 bare conjecture, may appear from the boiling up of the water at first in the less 



