378 WRITINGS OF JOSEPH HENRY. [1874 



keeper to give it proper attendance, discouraged for a time 

 efforts in this line. 



Previous to the investigations of Prof. Alexander at the 

 expense of the Light-House Board, Mr. Daboll, of New Lon- 

 don had for several years been experimenting on his own 

 account with reference to a fog-signal. His plan consisted 

 in employing a reed trumpet, constructed after the manner 

 of a clarionet, and sounded by means of air condensed in a 

 reservoir, the condensation being produced by horse-power 

 operating through suitable machinery. Although the sound 

 of this was more penetrating than that of bells, still the ex- 

 pense and inconvenience of the maintenance of a horse, 

 together with the cost of machinery, prevented its adoption. 

 Mr. Daboll however after this presented to the board a mod- 

 ification of his invention, in which a hot-air engine of 

 Ericsson's patent was substituted as the motive power, instead 

 of the horse ; and the writer of this report, as chairman of 

 the committee on experiments in behalf of the board, 

 examined this invention and reported in favor of its adoption. 

 The other members of the committee made an unfavorable 

 report, on the ground that fog-signals were of little impor- 

 tance, since the mariner should know his place by the 

 character of his soundings in all places where accurate sur- 

 veys had been made, or should not venture near the coast 

 until the fog was dissipated. The board however established 

 Daboll trumpets at different stations which have been in 

 constant use up to the present time. 



PAET I.— INVESTIGATIONS FROM 1865 TO 1872. 

 (Report of the United States Light-House Board for 1874, pp. 87-107.) 



Experiments near New Haven, in 1865. 



The subject of sound, in connection with fog-signals, still 

 continued to occupy the attention of the board, and a series 

 of investigations was made in October, 1865, at the light- 

 house near New Haven, under the direction of the writer of 

 this report, in connection with Commodore, now Admiral L. 



