of Edinburgh, Session 1885 - 86 . 439 
what could be obtained from the surface of the Seine bank and the 
Dacia bank, they have reached limiting conditions. Had they 
risen to their present level in equatorial regions, they would doubt- 
less have been occupied by reef-building species, and would have 
formed true coral islands. 
We have seen above that, on the Coral patch, the lead was 
dropped by chance on the face of a precipitous cliff at least 200 
fathoms high. On the Dacia bank the mark buoy happened to be 
let go just on the edge of the bank in 175 fathoms. On trying to lift 
the moorings the buoy-rope carried away, and it was found to have 
been chafed through about 100 fathoms from the surface, or 75 
fathoms above the ground. The currents had evidently been rubbing 
it against the edge of the cliff during the two days that it was down. 
From the mark buoy the “ Dacia” steamed west for about 10 miles, 
taking up and down soundings every mile, and “ flying soundings ” 
with a pneumatic sounding-machine which I constructed on board. 
It worked extremely well with the ship going 7 knots, and in water 
ranging from 50 to 100 fathoms in depth. About 8 miles west of 
the buoy, the edge of the bank was again struck. After an up and 
down sounding of 86 fathoms, a flying sounding gave 110 fathoms. 
The engines were immediately stopped and put astern, when an up 
and down sounding gave 333 fathoms. The distance between these 
soundings could not have been more than a quarter of a mile, which 
gives an average gradient between the soundings of nearly 45°. 
To the westward of the 333 fathoms sounding, 619 fathoms were 
found at 1 mile, and 844 fathoms at 2 miles. At this sounding a 
lj-inch mud tube was used, and it brought up a good sample of 
very coarse-grained Globigerina ooze, with many pteropod and other 
shells. 
In the following table will be found the slopes on the Dacia and 
the Seine banks, as observed between adjacent soundings, also those 
on the slope of Bermuda and adjacent banks, taken from the most 
recent Admiralty charts : — 
