426 Sir James N. Douglass [March 15, 



determined by the Trinity House, in 1877, to erect a new lighthouse 

 at a distance of 120 feet from Smeaton's tower, where a safe and 

 permanent foundation was found, but at a much lower level, which 

 necessitated the laying of a large portion of the foundation masonry 

 below low water. The foundation stone of this work was laid on the 

 19th August, 1879, by H.E.H. The Duke of Edinburgh, Master of 

 the Trinity House; assisted by H.E.H. The Prince of Wales, an 

 honorary Elder Brother of the Corporation. 



On the 1st June, 1881, H.E.H. The Master, when passing up 

 Channel in H.M.S. Lively, landed at the rock and laid the last 

 stone of the tower ; and on the 18th May of the following year H.E.H. 

 lighted the lamps, and formally opened the lighthouse. The edifice 

 ■was thus completed within four years from its commencement, at a 

 cost of 59,255?. The work was executed under the immediate direc- 

 tion of the Trinity House and their engineer, and with a saving of 

 24,000?. on the lowest sum at which it had been found that it could 

 be executed by contract. Every block of granite in the structure, is 

 dovetailed together, both vertically and horizontally, on a system 

 devised by my father, and first adopted at the Hanois rock lighthouse, 

 off the west coast of Guernsey. The illuminating apparatus consists 

 of two superposed oil lamps, each of six concentric wicks ; and of 

 two drums of lenses of 920 mm. focal distance, twelve lenses in each 

 drum. The optical apparatus is specially designed on the system of 

 Dr. John Hopkinson, F.E.S. for a double flashing light, and shows 

 two flashes in quick succession, at intervals of half a minute. Atten- 

 tion has of late been directed to the subject of superposed lights in 

 lighthouses, which became a necessity when several small luminaries 

 had to be substituted for the large coal, or wood, fire of our early 

 lighthouses. The credit of first superposing lighthouse luminaries 

 is doubtless due to Smeaton, who lighted his lantern in 1759 with 

 24 large tallow candles in two tiers. The idea was followed in 

 1790 with the first revolving light, established at the St. Agnes 

 lighthouse, Scilly Islands, which consisted of 15 oil lamps and 

 reflectors, arranged in three groups, and in three tiers. The number 

 of the lamps and reflectors at this and other first-class lights, was 

 afterwards extended to 30, and in four tiers. In 1859 Mr. J. W. 

 D. Brown, of Lewisham, proposed superposed lenses for signal and 

 lighthouse lanterns, with a separate light for each tier of lenses. In 

 1872 Mr. John Wigham, of Dublin, proposed superposed lenses for 

 lighthouses, in conjunction with his large gas flames, and the first 

 application of these was made in 1877, at the Galley Head light- 

 house, County Cork. In 1876 Messrs. Lepaute and Sons, the 

 eminent lighthouse optical engineers of Paris, made successful experi- 

 ments with superposed lenses and mineral oil flames, and one of their 

 apparatus was exhibited at the Paris International Exhibition of 1878. 

 The results of these experiments were given by M. Henry Lepaute, 

 in a paper contributed to the Congress at Havre, in 1877, of the 

 French Association for the Advancement of Science. The Eddy- 



