442 Sir James N. Douglass [March 15, 



advice of Faraday, made experimental trials with it in London, and 

 afterwards gave it a practical trial at the Dungeness lighthouse, 

 where experiments were made with it against bells, guns, and a reed 

 fog horn of Professor Holmes, whose services have been already 

 referred to in connection with the first practical application of 

 the electric light. This fog horn of Holmes was sounded 

 by steam, direct from one of the boilers employed at the station for 

 his electric lio^ht. The results of these experiments were in favour 

 of Daboll's trumpet, and in 1869, one of these instruments was 

 installed on board the Newarp light- vessel. In the same year, Holmes, 

 having effected further improvements with his steam horn, his 

 apparatus was fitted on board two light-vessels and sent out to the 

 coast of China, where they were found to give great satisfaction, as 

 compared with gong signals. In 1863 a committee of the British 

 Association for the Advancement of Science memorialised the 

 President of the Board of Trade, with the view of inducing him to 

 institute a series of experiments upon fog signals. The memorial, 

 after briefly setting forth a statement of the nature and importance 

 of the subject, described what was then known respecting it, and 

 several suggestions were made relative to the nature of the experi- 

 ments recommended. The proposal does not appear to have been 

 favourably entertained by the authorities to whom it was referred, and 

 the experiments were not carried out. In 1864 a series of experiments 

 was undertaken by a commission appointed by the Lighthouse Board 

 of the United States to determine the relative powers of various fog 

 signals which were submitted to the notice of the Board. In 1872, a 

 committee of the Trinity House, with the object of ascertaining the 

 actual efficiency of various fog signals then in operation on the North 

 American Continent, visited the United States and Canada, where 

 they found in service Daboll's trumpets, steam whistles, and siren 

 apparatus, devised by Mr. Felix Brown, of Progress Works, New 

 York, sounded by steam and compressed air. From the report of the 

 Trinity House Committee, it does not appear that they were greatly 

 impressed with this instrument, but j)i'obably they had not an 

 opportunity of testing its real merits, as compared with other signals. 

 The late Professor Henry, of the United States Lighthouse Board, 

 entertained a very high opinion of the siren, and on his advice, 

 and the urgent recommendation of Professor Tyndall, one of 

 these instruments was sent to England and included in the fog 

 signal experiments at the South Foreland in 1873-4. This in- 

 vestigation was carried out by the Trinity House, with the 

 view of obtaining definite knowledge as to the relative merits of 

 various sound-producing instruments then in use, and also of ascer- 

 taining how the proj)agation of sound is affected by meteorological 

 phenomena. Professor Tyndall, as scientific adviser of the Trinity 

 House, conducted the investigation, aided by a committee of the 

 Trinity House and their engineer. These experiments were extended 

 over a lengthened period, in all conditions of weather, and the well- 



