10 
surface of the sea. Such dangers laying in the track of navigators, and 
liable to be fallen in with during the night and the tempest, it is evident, 
must have addressed themselves with great terror to the imagination of 
sailors, more especially as well-known dangers of this character do really 
exist, and are occasionally visited. For instance, Rockall, a high conical 
rock, seventy or eighty feet above water, laying about two hundred 
miles N.E. of Ireland,which appears to be the apex of a submarine eleva¬ 
tion or bank, over the general extent of which the soundings are from fifty 
to a hundred fathoms. A still more remarkable instance is the Rocks 
of Penedo de St. Pedro, in lat. 0° north, and 29° 19' west longitude, 
described by Captain Fitzroy, who landed on them in 1832, as a cluster 
of craggy rocks, a quarter of a mile in extent, the highest about sixty feet 
above the surface, apparently the summit of a steep-sided mountain, and 
unconnected with any bank, as no soundings could be obtained at one or 
two miles distance, though tried with a line of two hundred fathoms. The 
nautical reader will probably remember that a Dutch ship was lost on 
these rocks about three years ago. Most of the crew succeeded in landing 
upon them, and after some days’ severe suffering for want of water, were 
rescued by a vessel passing. Properly speaking, Rockall, and Penedo de 
St. Pedro are not vigia, which term is correctly applied to doubtful dangers 
alone; and in the present state of the navigation of the Atlantic, it is only 
rocks or shoals laying level, or a little below the surface of the sea, that 
can remain doubtful: when in this position, however, it is astonishing how 
long unknown, or at least uncertain, a rock may exist comparatively near 
the shore, and in the track of vessels. We believe some dangers of this 
sort are unsettled even on our own coast; but there is a well-known 
instance in the Dsedalus rock, laying some forty miles from Cape St. Vin¬ 
cent, whose reality, doubtful since the middle of last century, was only 
verified without further question, by two or three vessels striking upon it 
about thirty years ago.* To illustrate the extreme difficulty of solving the 
question of the existence of a doubtful rock in the open sea, out of sight 
of land, and consequently incapable of being brought within the test of 
cross-bearings, we will abridge from Purdy’s Memoir of the Atlantic 
Ocean, an account of Aitkin’s Rock. 
The original notice of this danger was published in 1740, wherein it 
was stated to have been seen in lat. 55° 18' N., and 11° 14' W., 94 miles 
distant from Tory Island, by Captain Aitkin and the crew of the “Friend- 
* Jan. 1849. We are informed by Captain Livingston that the existence of the 
Dsedalus rock is still questioned. 
