PHILOSOPHICAL SOCIETY OP AVASHINGTON. 319 



dangerous stations, notwithstanding its higher consumption of 

 steam or heat power.* 



Partly under the stimulus given to the sale of lard-oil by the 

 striking proofs of its excellence as an illuminant under favoi'- 

 able conditions, furnished by Henry, this article slowly advanced 

 in price ; though probably not to an extent of more than a fourth 

 part additional cost. Henry's energies again were called into 

 requisition to devise a remedy. Neither gas, nor electricity, the 

 favorite means of numerous projectors and advisers, appeared 

 justified, on the score of economy.f A new series of elaborate 

 experiments was undertaken to determine whether mineral oil 

 (so abundant as to be easily procurable at one-third the cost of 

 lard oil) could not be made available. The great improvements 

 introduced into its preparation in later years by high distillation, 

 seemed to justify the attempt. Not only was a laborious inquiry 

 into the best conditions of combustion, by precise photometric 

 measurement required, but for the security of the service, equally 

 laborious examinations into the best practicable methods of test- 

 ing, of handling, and of storing this material.| To secure a 



* Major G. H. Elliott, commissioned by the U. S. Light-house Board to 

 make a tour of inspection of European Light-house establishments in 

 1873, in his Report published by the Senate in 1874. says of the British 

 and French systems, " I saw many details of construction and administra- 

 tion wbich we can adopt to advantage, while there are many in which 

 we excel. Our shore fog-signals particularly, are vastly superior both in 

 number and power." (Report on European Light-houses, p. 12.) "To 

 the careful and laborious investigations and experiments of the distin- 

 guished Chairman of the Light-Louse Board, prolonged through a series 

 of years, and prosecuted under a great variety of conditions, is largely 

 to be attributed the acknowledged superiority of our fog-signal service." 

 {Journal of Frnnklin Institute, Jan. 1876, vol. Ixxi. p. 43.) 



f Report of L. H. Board for 1874, p. 11. No agency (for whatever 

 purpose) has proved so enticing to the half-informed as electricity. For 

 years past scarcely a month has elapsed without some new form of patent 

 electric-light, or some marvellous application of electric-lights, being 

 pertinaciously iirged by sanguine "reformers" upon the Light-house 

 Board for adoption ; some of these ideal schemes being the mounting of 

 electric-lights on buoys, or on the niasts of light-ships, or their suspen- 

 sion from moored balloons. Many eminently original minds have earn- 

 estly desired to obtain contracts for supplying all the Light-houses with 

 oxy-hydrogen lime lights. In a fog, the most powerful electric-light is a» 

 useless as the cheapest kerosene lamp. 



X "It has been established that the ordinary fire-test is insufficient a& 

 usually applied, and that an explosive mixture may be formed by con- 

 fining the vapors given ofi^ at a temperature in some cases twenty degrees 

 lower than that certified to by the public inspector. That this inquiry is 

 of great practical importance to the Light-house system, must be evident 

 when we reflect that means must be devised for testing the oil oflfered for 

 acceptance in accordance with contracts ; for storing it ; for transporting 

 it to light-house stations ; for preserving it in butts at the stations ; and 

 for the instruction of the keepers in its daily use." {Report L. H. B, 

 1877, p. 5.) 



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