1889.] on Beacon Lights and Fog Signals. 435 



Bimset and off again at sunrise. It is also arranged for periodic ad- 

 justment, f(jr the lengthening and shortening of the nights throughout 

 the year. This automatic light is in the charge of a boatman, who visits 

 it once a week, when he cleans and adjusts the apparatus, and cleans 

 the glazing of the lantern. An automatic lighthouse similar to that 

 at Broadness has Leon lately installed at Sunderland by the Kiver 

 Wear Commissioners, on a pier which is inaccessible in stonny 

 weather. In 1881-82 several beacons automatically lighted by petro- 

 leum spirit, on the system of Herr Lindberg and Herr Lyth, of 

 Stockholm, were established by the Swedish Lighthouse authorities, 

 and are reported to be working efficiently. In 1885, a beacon or 

 automatic liglithouse on this system was installed by the Trinity 

 House on the Thames, near Gravescnd, and has been found to work 

 efficiently. The light is occulting at periods of about two seconds ; 

 the ocoultations are produced by an opaque screen rotated around the 

 light, by the ascending currents of heated air from the lamp acting 

 on a horizontal fan. As there is no governor to the apparatus the 

 periods of the occultations are subject to slight errors compared with 

 those of tlie gas light controlled by clockwork. In 184d an iron 

 beacon, lighted by a glow lamp and the current from a secondary 

 battery, was erected on a tidal rock near Cadiz. Contact is made 

 and broken by a small clock, which runs for 28 days, and causes the 

 light to flash for five seconds at periods of half a minute. The clock 

 is also arranged for eclipsing the light" between sunrise and sunset. 

 The apparatus is the invention of Don Isas Lavoden, of Cadiz, to 

 whom I am indebted for kindly showing me the light in action when 

 on a visit to Cadiz in 1885. There is every probability that auto- 

 matic beacons, lighted either by electricity, gas, or petroleum spirit, 

 will, in consequence of their economy in maintenance, be extensively 

 adopted in the future. 



Coal and wood fires, the flames produced by the combustion of 

 tallow, nearly all the animal, vegetable, and mineral oils, coal and oil 

 gas, and the lime light, have been employed from time to time in 

 lighthouse illumination, and last but not least, the electric light. 

 None of tliese illuminants have received such universal application in 

 all positions both asliore and afloat as mineral oil at the present 

 moment, and justly so, when we consider its efficiency and economy 

 for the purpose. So recently as 1822, the last beacon coal fire in 

 this country was replaced by a catoptric oil light, at Saint Bees light- 

 house, on the coast of Cumberland. We have here diagrams of two 

 of these coal fire beacons, one of them designed and erected by Smeaton 

 in 1767 on his lighthouse at the Spurn Point, on the east side of the 

 entrance to the Humber. So late as 1845 sperm oil was entirely used 

 in the lighthouses and light-vessels of the Trinity House; but, 

 shortly afterwards, colza w^as adopted with the same efficiency, and 

 with a saving in annual cost of about 44 per cent. In 1861, experi- 

 ments were made by the Trinity House for determining the relative 

 efficiency and economy of colza and mineral oil for lighthouse illumi- 



