320 BULLETIN OF THE 



proper oxygenation in burning, a modification of the lamp was 

 required. " It was soon apparent that the use of mineral oil 

 would necessitate a change of lamps, and attention is now 

 directed to the perfection of one v/hich will produce the best 

 results from this illuminant. It is thought that the lamps now 

 used with lard-oil can be converted at no great expense and 

 successfully used with mineral oil. Our experiments have shown 

 that this oil can be more readily used in the smaller lamps ; and 

 it is proposed as soon as suitable ones can be prepared, to put it 

 into use at such stations of the fifth and sixth order, as may be 

 thought expedient ; when if it be found satisfactory, an attempt 

 will be made to substitute it for lard-oil in lamps of the higher 

 orders."* " This change is proposed entirely with reference to 

 economy ; for it has been found by repeated experiment, that 

 while a somewhat superior light may be obtained from a smaU 

 lamp charged with kerosene, a larger lamp charged with lard-oil 

 affords the greater illuminating power. So great is this differ- 

 ence in lamps of the first order with five wicks, that the rates of 

 light from kerosene and lard, are as three to four respectively. 

 Since the safety of the keeper and the continuity of the light are 

 essential elements in the choice of an illuminant, a thorough 

 acquaintance with the nature of the substance is essentially 

 necessary. With a view therefore to the introduction of kerosene, 

 a series of experiments have been made during the last two 

 years on the different varieties of this material found in the 

 market."! 



In 18T1, on the resignation of Admiral Shubrick, Henry was 

 chosen as the Chairman of the Light-house Board; and his 

 energetic labors in behalf of the service, fully vindicated the 

 wisdom of the choice. Punctual in his attendance on the weekly 

 meetings of the Board, he inspired others with a portion of his own 

 zealous devotion. Nor did he fail to urge upon the Government 

 the constant need and responsibility of maintaining an efficient 

 establishment. He emphatically declared that " the character 

 of the aids which any nation furnishes the mariner in approaching 

 and leaving its shores, marks in a conspicuous degree its advance- 

 ment in civilization. Whatever tends to facilitate navigation or 

 to lessen its dangers, serves to increase commerce ; and hence is 

 of importance not only to the dwellers on the seaboard, but to 

 the inhabitants of every part of the country. . . . Therefore 

 it is of the first importance that the signals, whether of light or 

 sound, which indicate the direction of the course, and the beacons 

 which mark the channel, shall be of the most improved character, 

 and that they be under the charge of intelligent, efficient, and 



* Report L. H. Board, 1 875, p. 6. 



t Report L. H. Board, 1877, p. 4. 



94 



