The Cloch Lighthouse, Gourock.

As a child growing up beside the Clyde at Gourock I would often be wakened from my slumbers by the giant fog-horn operated at this magnificent lighthouse.
It is described as thus: "Siren foghorn operated by compressed air, furnished by engines of about 30HP, the signal comprising two 1½ second blasts every 50 seconds."
The building itself as thus:"A white tower with a black band, 76 feet high with the focal plane 76 feet above High Water, showing a white single flashing light having the characteristic of 1 flash every 5 seconds. The effective intensity of the light is about 40,000 candlepower and the geographical range in clear weather is 14 miles"
During WW2 a giant anti-submarine boom extended from this point to Gantock Rock on the Dunoon side. This was the start of one of the safest and most important anchorages in the UK. Many U-boats tried to penetrate it, but it remained unimpeached.
It is now a private dwelling house.