75 
of Edinburgh, Session 1872 - 73 . 
case this year, the sea in the roads and at the beach is not nearly so 
smooth ; up to this time we have had none of the mud cones burst- 
ing at the beach, neither in the roads, as the waves tumble in per- 
fectly clear; there was a heavy surf from the 26th ultimo to 9th 
instant, but never, in any instance, for these last eleven years, has 
the rain held off so long as in this, and the roads and beach have 
always, by the end of May, been perfectly smooth.” 
Since that letter was written, the bank has left Allippey, and 
has shifted some four miles down the coast, which considerably 
complicates the theories put forward. The oscillation of the bank 
— for it is said by some to have previously had a northward ten- 
dency — is very puzzling, viewed in connection with any supposed 
underground communication with the backwaters. The smooth- 
ness in rough weather is said to extend out to about the six fathom 
line. This is a point worth noticing, because, unless the mud sud- 
denly stops there, it shows the extreme limit at which the waves on 
this coast have any effect on the bottom, even when that is com- 
posed of very fine slushy mud. 
Mr Crawford states that the mud cones he describes take place 
only during the monsoon. At all events, I did not see any in action 
during my visit. He told me, likewise, that during the monsoon 
there is fresh water on the Allippey bank, but could not say whether 
it was succeeded by salt water to the north or south. This would 
require to be known, to make the existence of fresh water during 
the rains at all curious. It is possible that the fresh water may 
extend all the way to Cochin harbour entrance, and owe its existence 
either to that outlet on the north, or to some other outlet to the 
south. 
Towards the formation of any theory about the Allippey bank, 
it will be useful to note that Mr Crawford has measured the level 
of the water in the backwater during the height of the monsoon, 
and found it to be 3 feet 2 inches above the sea-level. This gives a 
hydrostatic pressure from the backwater of less than a pound and a 
half on the square inch. The backwater is about two and a half 
miles from the sea at Allippey. 
Mr Crawford, when I saw him, had an idea that volcanic action 
has something to do with the mud cones described by him, but was 
unable to overcome the difficulty I suggested, that it was only 
