398 
“ In the next place (which is what more particularly deserves our 
attention on this occasion), it should seem that iron, and the solu- 
tions of iron, contribute very much to hasten and promote the pro- 
gress of the concretion and induration of stone, whenever they meet 
and are united with those cementing crystalline particles, which 
there is reason to believe are the more immediate cause of the con- 
solidation of all stones and marbles whatsoever, and which do very 
much abound in sea-water.” 
The same conclusion, he also thinks, may be drawn from another 
incrustation. “ Some fishermen, sweeping for anchors in the Gull- 
stream (a part of the sea near the Downs), drew up a very curious 
old swivel gun, near eight feet in length. The barrel of the gun, 
which was about five feet long, was of brass ; but the handle, 
whereby it was to be turned or traversed, which was about three 
feet in length, and also the swivel and pivot on which it turned, 
were of iron ; and all round these latter, and especially about the 
swivel and pivot, were formed exceeding hard incrustations of sand, 
converted into a kind of stone, of an exceeding strong texture and 
firmness : whereas round the barrel of the gun, except where it was 
near adjoining to the iron, there were no such incrustations at all. 
The incrustation round the iron part of this gun was also the more 
deserving of attention, because it enclosed within it, and also held 
fast adhering to it on the outside, a number of shells and coralline, 
just in the same manner as they are often found in a fossil state ; 
much resembling in colour and appearance some of the masses of 
fossil bodies found near Chippenham, in Wiltshire. — It is to be ob- 
served, notwithstanding the iron was, by some means or other, the 
cause of this induration, it was very little dissolved, although the 
gun must have remained in the sea above 200 years, and probably a 
good deal longer. 
“ Dr. Fothergill, on passing through the streets of London in his 
walks, before the sign-irons were taken down, perceived that, on the 
