The Treaty Ports of China and Japan (1867)

...  The sailing distance round Hongkong estimated in 1843, 
(Sir E. Belcher's survey) at 26.85 miles, though a walk round it, foJ— 
lowing the irregular indentations of the coast, gives a distance of some 
few miles more. Its extreme length is nearly nine, and its greatest 
breadth a little more than four miles. 

   Its formation is volcanic, a rugged mountainous ridge running from 
E. to W. with six peaks of from 1,016 to nearly 1,900 feet in height …