312 MEMORIAL OF JOSEPH HENRY. 



this instrument frequently made itself heard at a distance of fifteen, 

 and twenty miles. Henry's large experience with the occasional 

 aerial impediments to sound propagation,* and his strong sense of 

 the vital importance of having fog-signals recognized at a distance, 

 under the most adverse conditions, led him to favor the introduc- 

 tion of the most powerful sounders attainable, without absolutely 

 limiting the decision to their relative economy. Hence he was the 

 first to devise improvements in the siren, and to press its adoption 

 at important or dangerous stations, notwithstanding its higher con- 

 sumption of steam or heat power, f 



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

 striking proofs of its excellence as an illuminant under favorable 

 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. J A new series of elaborate experiments was 

 undertaken to determine whether mineral oil (go 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 prep- 



* An abstract of Henry's elaborate and invaluable researches on some abnormal 

 phenomena of Sound the crowning labor of his life, must be reserved for a con- 

 cluding section. 



f 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 administration which we can adopt to advan- 

 tage, 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 dis- 

 tinguished Chairman of the Light-House Board, prolonged through a series of 

 years, and prosecuted under a great variety of conditions, is largely to be at- 

 tributed the acknowledged superiority of our fog-signal service." (Journal of 

 Franklin Institute, Jan. 1876, vol. Ixxi. p. 43.) 



% Report oj 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 

 marvelous application of electric-lights, being pertinaciously urged 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 masts of light- 

 ships, or their suspension from moored balloons. Many eminently original 

 minds have earnestly desired to obtain contracts for supplying all the light- 

 houses with oxy-hydrogen lime lights. In a fog, the most powerful electric-light 

 is as useless as the cheapest kerosene lamp. 



