PHILOSOPHICAL SOCIETY OF WASHINGTON. 321 



trustworthy attendants."* And rising to a higher argument, he 

 pointed out tliat " it is not alone in its economical aspect that a 

 liglit-house system is to be regarded : it is a life preserving es- 

 taljlishment founded on the principles of Christian benevolence, 

 of which none can so well appreciate the importance as he who 

 after having been exposed to the perils of the ocean — it may be 

 lor uiontlis — finds himself approaching in the darkness of night 

 a lee shore. But it is not enough to erect towers, and establish 

 other signals : they must be maintained in an efficient state with 

 uninterrupted constancy."! 



A formal report made to the Hon. Secretary of the Treasury 

 by the Naval Secretary of the Light-house Board, dated May 

 21st, 1878, (very shortly after Henry's death,) simply detailing 

 for information, the character of his gratuitous services to the 

 Light-house establishment during a quarter of a century, (and 

 not intended for the public,) takes the inevitable form of eulogy. 

 A portion of it is here quoted. 



"As chairman of this committee. Professor Henry acted as the 

 scientific adviser of the Board. But in addition it was his duty 

 to conduct the experiments made by the Board, not only in the 

 matter of original investigation and testing of the material used, 

 but in examining and reporting on the models, plans, and theories 

 presented by others to the Board. The value of the services he 

 rendered in this position is simply inestimable. He prepared 

 the formula for testing our oils ; he conducted the series of ex- 

 periments resulting in the substitution of lard-oil for sperm oil, 

 which effected an immense saving in cost ; and he also conducted 

 the experiments which have resulted in making it possible to 

 substitute mineral oil for lard-oil, when another economy will be 

 made. His original investigation into the laws of sound have 

 resulted in giving us a fog-signal service conceded to be the best 

 in the world. His examinations into the action of electricity, 

 has enabled the Board to almost completely protect its stations 

 from the effect of lightning. The result of his patient, con- 

 tinuous, practical experimentation is visible everywhere in the 



* Report of L. H. Board, 1873, pp. 3, 4. The coast line of the United 

 States is far more extended than that of any other nation on tlie globe. 

 "The magnitude of the Liglit-house system of the United States may he 

 inferred from tlie following facts: from tlie St. Croix River on the bound- 

 ary of Maine, to the mouth of the Rio Grande in the Gulf of Mexico, in- 

 cludes a distance of over 5,0(.iO miles ; on the Pacific coast, a length of 

 about 1,500 miles ; on the great northern Lakes, about 3,000 miles ; and on 

 inland rivers about 700 miles ; making a total of more than 10,000 miles. 

 Nearly every square foot of the margin of the sea throughout the whole 

 extent of 5,000 miles along the Atlantic and Gulf coast is more or less 

 illuminated by Light-house rays ; the mariner rarely losing sight of one 

 light until he has gained another." (p. 4, of same Report. J 



t Report L. H. B. 1874. p. 5. 



VOL. II.— 21 95 



