110 NAVAL SCIENCES. 



lanterns are all of cast-iron. C is the clock-work ; D, the lighting appara- 

 tus ; and E, a lightning-rod. The tower was erected without any scaffold- 

 ing. On the floor of each story {fig. 22) a projecting derrick, d, was 

 arranged, with a windlass at its foot, a. The rope of this, h, passed around 

 a pulley, c, and raised the plate e, which was steadied below by a guy, /. 

 A considerable number of these light-houses have been erected with 

 success. 



7G2 



