“ The Ridge Shoals near the middle of the strait are over 8 miles long, and have a depth of 10 to 24 feet. Both the English and French shores are formed by chalk cliffs. The strait has been carefully surveyed by engineers with a view to bridging or tunneling it. There is great opposition in England, on military grounds, against the construction of a tunnel. It is, perhaps, the most frequented maritime route in the world. Captain Webb, of the British mercantile navy, in August, 1875, swam the strait in 213⁄4 hours. ”