The Cloch Lighthouse is located on Cloch Point, Inverclyde, three miles south west of Gourock on the A770, on the east shore of the Firth of Clyde, directly opposite Dunoon. Designed by Thomas Smith, with Stevenson, and built in 1797. Characteristic Range: White flash every 3 seconds. This location is also the site of survey bench mark, Flush Bracket G343: Cloch Lighthouse, at NS 2032 7588.
The original Cloch light was illuminated by acetylene, while the dioptric and catadioptric lenses floated in baths of mercury, and were rotated by a clockwork mechanism powered by falling weights, which the keeper would hand wind to the top of the tower each time they ran down. This operation had to be repeated every two to three hours depending on the system, and could not be missed or the rotation would stop, rendering the light useless. The keeper also had to tend the light, ensuring the burners and fuel supply were operational, and maintain the lenses and windows, keeping them clear of any internal or external contamination. Photographs of the lighthouse, available from the links below, suggest the foghorns were added much later, between 1895 and 1897.
The light was further described in A short history of the Clyde Lighthouses Trust as follows:
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.
Although there is no detailed description of the optics, the description of "dioptric and catadioptric lenses" implies the use of convex lenses or refractors, and of a combination of mirrors and lenses. This probably just means there was a reflector behind the light source to cast the light forward, and that it was then formed into a beam by the usual Fresnel lens used in lighthouses.
The foghorn was described as:
Siren foghorn operated by compressed air, furnished by engines of about 30HP, the signal comprising two 1½ second blasts every 50 seconds.
The book also notes the Cloch to have featured a "talking beacon" in its past:
The Clyde Lighthouses were the first authority of the kind to establish ‘talking beacons’. This instrument was a sensational novelty in its period. The device is quite simple in its application. A transmitter sends out from an ordinary gramophone disc the name and position of the lighthouse and then counts up to thirty in measured terms. A ship coming into the Clyde can thus get a bearing through its own instruments, even in fog. It is likely that the ‘talking beacon’ will be supplanted by apparatus of a still more advanced kind, and in fact these wireless signals from Cumbrae and Cloch — for Toward is not so equipped — are now used mostly for calibrating the navigational devices of new ships on their trials, but it was one of the notable contributions of the Stevenson family to safe navigation.
As with all the country's lighthouses, the Cloch light is now fully automated and unmanned. At some time, believed to be during the 1990s, the main light was closed down and replaced by an optic mounted on a pole just outside the lantern. This can be seen on the seaward side of the lantern pictured at the head of this page. The light continues to flash with the same character, but is of restricted range - from the other side of the firth it is hard to distinguish it from adjacent street lights.
- 1895 photograph, no foghorns evident
- 1897 photograph, foghorns visible
- 1936 photograph
- 1936 photograph
- Bench mark details
- Site containing lighthouse history - uses evil frames, so no link - Search site for 'lighthouse'
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