PHILOSOPHICAL SOCIETY OF "WASHINGTON. 135 



A communication was then read by Mr. A. B. Johnson on 



THE HISTORY OF THE LIGHT HOUSE ESTABLISHMENT OF THE 

 UNITED STATES. 



Mr. Johnson read from a paper he had prepared for pub- 

 lication elsewhere, on the History of the Light-house Establishment 

 of the United States, tracing its rise and progress from the first 

 beacon which was erected on Point Allerton, entrance to Boston 

 Harbor, in 1673, to the present time. He gave some account of 

 the eight light-houses built by the Colonies ; then of twelve built 

 by the General Government prior to 1812, then of the progress of 

 the establishment, under the charge of Mr. Pleasanton, an Auditor 

 of the U. S. Treasury aud the Acting Superintendent of the Lights, 

 when the number increased to some three hundred and twenty-five ; 

 then of the causes which led to the creation of the provisional Light- 

 House Board, and then of the erection of the permanent Light- 

 House Board, and of the improvements the Board had since made, 

 in all the arts and sciences connected with the erection of the light- 

 houses and the establishment of cognate aids to navigation. Mr. 

 Johnson then gave some account of light-house construction and 

 of the different kinds of light-towers, material and style of the 

 structures used, and of the problems solved in deciding on the 

 various subaqueous foundations required. He illustrated his sub- 

 ject by the exhibition of large photographs of such stone light- 

 houses as that on Spectacle Reef, Michigan, of such harbor lights 

 as that on Thimble Shoal, entrance to Hampton Roads, Virginia, 

 such skeleton iron houses on driven piles as that on Fowey Rocks, 

 Florida Reef, and the tripod erected on Paris Island, Port Royal 

 Sound, S. C, and of the remarkable stone light-house recently 

 built on the summit of Tillamook Rock off the coast of Oregon. 



Some account was given of the fog-signals used in this country, 

 and a large crayon of the syren, the most powerful fog signal 

 known, was shown. 



Mr. Johnson spoke of the fact thus noted by Professor Henry : 

 " It frequently happens on a vessel leaving a station that the sound 

 is suddenly lost at a point in its course, and after remaining inau- 

 dible some time, is heard again at a greater distance, and is then 

 gradually lost as the distance is further increased." In connection 

 with this he exhibited a chart showing the site of Beaver Tail Light- 

 House on the south point of Conauicut Island, between the two 



