1875] WRITINGS OF JOSEPH HENRY, 477 



INVESTIGATIONS RELATIVE TO ILLUMINATING MATERIALS. 

 (Report of the United States Light-House Board for 1875; pp. 86-103.) 



Preliminary Remarks. 



It has been the policy of the Light-House Board since its 

 first establishment not only to adopt the latest improvements 

 that have been made in other countries, but also to add by 

 original investigations to the sum of knowledge respecting 

 aids to navigation. In accordance with this policy, the Board 

 has endeavored to keep itself informed as to the progress of 

 the light-house systems of other countries, and in the erec- 

 tion of new towers and the supply of new apparatus, to adopt 

 those improvements which have from actual experience been 

 preferred ; and furthermore, the committee on experiments 

 has devoted a portion of every year to investigations which 

 might develop new facts tending to greater economy or 

 efl&ciency in the various appliances by which the dangers of 

 navigation are diminished. 



At the commencement of the operations of the Light- 

 House Board, in 1852, sperm oil was generally employed for 

 the purpose of illumination. This was an excellent illumi- 

 nant, but as its price continued to advance from year to 

 year, it was thought proper to attempt the introduction of 

 some other material. The first attempt of this kind was that 

 of the introduction of colza oil, which was generally used in 

 the light-houses of Europe : — an oil extracted from the seed 

 of a species of wild cabbage, known in this country as rape, 

 and in France as colza. For this purpose a quantity of rape- 

 seed was imported from France and distributed — through the 

 agricultural department of the Patent Ofiice, to dififerent parts 

 of the country, with the hope that our farmers might be in- 

 duced to attempt its cultivation. Although the climate of 

 the country appeared favorable to its growth, and special 

 instructions were prepared and distributed by the Light- 

 House Board — for its culture and the means of producing oil 

 from it, yet the enterprise was not undertaken with any ap- 



