It is obviously necessary that lighthouses should regulate their lights according to the hour. In Scotland, and indeed elsewhere, before the days of electric communication, timepieces at the lighthouses were corrected by means of sundials, instrument which were commonly found there. The Commissioners of Northern Lights made annual inspections of Scottish lighthouses. They were concerned to find that sundials were not always accurately set. On one occasion, at Chanonry Point in the Inner Moray Firth on the east coast of Scotland there turned out to be a thirty minute difference between local and Greenwich time. This was blamed on the sundial.
To improve timekeeping a general order was made on 29 January 1852 requiring that lighthouse clocks be set at local time calculated from sundial readings. The order read as follows: The Lighthouse Timepiece is to be kept right by observing, if possible once a week, the indication of the Sun-dial in the following manner: The Principal Keeper shall go to the dial when the sun is shining and shall watch until the shadow of the style touches any hour, half hour or other time agreed upon before hand with the Assistant, who shall stand on the balcony waiting a signal from the Principal. The Principal shall then make the signal, on seeing which, the Assistant shall immediately set the timepiece to the time already agreed upon. The Principal shall then take a note of the Equation of Time engraved on the Sun-dial, of the number of minutes by which the clock should differ from the time given by the dial; and shall afterwards at once proceed to the Lightroom where he shall put the timepiece back or forward according as the Clock shall be slower or faster than the Sun at the time. Thus were lighthouse lanterns controlled in 1852. The quotation above was taken from Scotland's Edge by Keith Allardyce and Evelyn M. Hood, Collins, Glasgow, 1986, ISBN 0 00 435660 8. -- Frank Evans
