440 



LIGHTHOUSE ESTABLISHMENT, THE UNITED STATES. 



top flange of this tier and the flanges of the 

 third section are six inches by one and three- 

 quarter inches. The flanges of succeeding sec- 

 tions are similar. The side flanges correspond 

 in size with the top flange of eacli panel. The 

 horizontal flanges have strengthening knees. 

 A nine-inch interior lining of brick is built be- 

 tween the lower flanges. The whole structure 

 rests on an eight-inch concrete foundation, to 

 which the lower iron section is secured by thir- 

 ty-six anchor- bolts built into the concrete. 



Iron skeleton-towers are used on land where 

 the soil affords an inadequate support for a 

 masonry foundation, and where great cheap- 

 ness is required. That at the Southwest Pass 

 of the Mississippi may be regarded as typical. 

 Its foundation consists of a grillage of timber 

 resting on piles and covered with concrete, on 

 which are secured the iron socket disks from 

 which start eight external and one central shaft 

 of the skeleton. A two-story dwelling for 

 the keepers was placed within the shafts, and a 

 staircase was carried up to the lantern through 

 a tube as in case of the similar lights on sub- 

 aqueous foundations. These towers are found 

 to meet the purpose for which they were in- 

 tended, and are practicable where heavier 

 structures would not answer, affording less re- 

 sistance to the wind, and being much cheaper 

 to build. 



An interesting specimen of these skeleton iron 

 structures has recently been erected on Paris 

 Island, Port Royal Sound, South Carolina, and 

 is to exhibit the rear light of the Paris Island 

 ranges. Altogether, it is the most economical 



structure of its kind in the history of light- 

 house construction. The plan was born of 

 necessity, as it was found that the appropria- 

 tion made by Congress was insufficient to put 

 up the kind of structure usual in such a posi- 

 tion. The light exhibited is simply a locomo- 

 tive head-light, which is a powerful parabolic 

 reflector. It is claimed, however, that it is 

 possible to use on it a lenticular apparatus. 

 The tower is composed of columns, sockets, 

 struts, and tension-rods, framed in the form of 

 a triangular pyramid. It rests on six circular 

 iron disks, anchored to a concrete foundation. 

 The top sections of the side facing the chan- 

 nel, for which the tower is the guide, are pro- 

 vided with horizontal slats, to increase the 

 visibility of the beacon by day. The light, 

 which runs up and down in rails in the plane 

 of the structure, is housed by day, and at night 

 is hoisted to its place at the apex of the trian- 

 gle by machinery worked in the oil-house. The 

 large foundation-plates jire about forty feet 

 four inches apart. The focal plane of the 

 light is one hundred and twenty feet above 

 the sea level, but the top of the structure is 

 one hundred and thirty-two feet from the 

 ground. The cost of the iron work set up is 

 $9,400, and that of the structure complete 

 and lighted about $12,000. 



Saint Augustine lighthouse was built of 

 brick and iron, on Anastasia Island, on the 



PARIS ISLAND LIGHT, SOUTH CAROLINA. REAR RANGE. 



ST. AUGUSTINE LIGHTHOUSE, FLORIDA. 



eastern coast of Florida. Its base is a frustum 

 of an octagonal pyramid, on which rests the 

 frustum of a cone. The interior of the tower 



