476 WRITINGS OF JOSEPH HENRY. [1875 



ON THE EMPLOYMENT OF MINERAL OIL FOR LIGHT-HOUSE 



ILLUMINATION. 



(Eeport of the United States Light-House Board for 1875; pp. 5, 6.) 



- - - During the year, the Board — under the personal 

 direction of its chairman (assisted from time to time by 

 other members of the Board), has made an extensive and 

 careful series of experiments with regard to the merits of the 

 mineral oils of this country for the purposes of light-house 

 illumination. In order to obtain a great variety of oils, the 

 Board — on November 24, 1874 — advertised in various news- 

 papers published in different parts of the United States, in- 

 viting manufacturers and dealers to furnish it with speci- 

 mens of domestic mineral-oil for test as to their fitness for 

 light-house purposes. As soon as a sufficient quantity had 

 been received, the investigation was begun, and it has been 

 continued, with results which lead to the belief that there can 

 be had in this country an oil of suitable quality for light- 

 house use, and perhaps at a considerable reduction in ex- 

 pense. 



For the purpose of comparing our mineral-oils with those 

 now coming into use abroad, the Trinity House authorities 

 have been requested to send to the Board a specimen of that 

 used in lights under their control : and when this is obtained, 

 which is expected to be soon, further experiments will be 

 made. While with its present knowledge of the qualities of 

 these oils, the Board proposes to put them into use at light- 

 stations on the mainland, it would hesitate to endanger 

 valuable property, and the lives of its employes, b}^ placing 

 them on board of light-ships, in structures standing in the 

 water, or at other points from which the keepers could not 

 escape in case of accident. 



