20 
CRUISE OF E.M.S. CHALLENGER. 
George’s Hall, which, according to carved inscrip- 
tions, were mostly begun and completed between the 
years 1783 and 1789. At the period of our visit 
(1873), there were about 1800 guns mounted on 
the different fortifications. From the fortification a 
narrow and rather steep path leads to the Signal 
Station, at an elevation of 1300 feet above the level 
of the sea, where a sergeant of the Royal Artillery 
is placed in charge. From this point, an excellent 
view is obtained of the blue waters of the Mediterra- 
nean, and the many charming Spanish villages on 
the western shore of the bay. 
On the road down are to be seen some remarkable 
calcareous caves. That of St. Michael’s is situated 
at a height of 800 feet above sea-level. It contains 
beautiful stalactite formations, and seems to be of con- 
siderable extent. It is somewhat difficult to get about 
in its intricacies, but one is well repaid for the trouble. 
On the south-east side of the Rock is another of these 
caves, dedicated to St. Martin ; it is smaller, but the 
stalactites are of a purer whiteness. Here we dis- 
covered a large accumulation of sand, recent shells, 
and many heaps of bones and teeth of large her- 
bivorous animals which possibly existed here ages 
ago, when Gibraltar, instead of having its present 
salubrious climate, was covered with icy peaks and 
glacial boulders. 
Gibraltar has little save its barracks, military store- 
houses, and fortifications to attract strangers ; in fact, 
