Four instances have, however, been recorded of its occurrence on the British coasts, one on the coast of Norfolk in 1588, one in the Firth of Forth in 1648, one near Boston in Lincolnshire in 1800, while a fourth entangled itself among rocks in the Sound of Weesdale, Shetland, in September 1808.
Towards the north the site of the city slopes gently to the Firth of Forth and the port of Leith; while to the south, Liberton Hill, Blackford Hill, Braid Hills and Craiglockhart Hills roughly mark the city bounds, as Corstorphine Hill and the Water of Leith do the western limits.
The central public baths in Infirmary Street, with branch establishments in other parts of the town, including Portobello, are largely resorted to, and the proximity of the Firth of Forth induces the keener swimmers to visit Granton every morning.
Mill has shown that in the North Sea off the Firth of Forth the average depth of visibility of a disk in the winter half-year was 4; fathoms and in the summer half-year 62 fathoms, and, although the greater frequency of rough weather in winter might tend to obscure the effect, individual observations made it plain that the angle of the sun was the main factor in increasing the depth to which the disk remained visible.
The Firth of Forth had been selected, before the war, as the eastern terminus of a mid-Scotland canal which was to connect with the existing canal and follow its line for part of the way, and then crossing the low ground in the neighbourhood of Stirling, to enter Loch Lomond, and ultimately to reach the sea by a short canal from Balloch to a point near Dumbarton.
