THE TII^LAMOOK ROCK LIGHT COMPLETED 



The seas here are terrific. On October 19, 1912. a wave broke a pane of the lantern 132 



feet above the sea (see page 21) 



vessel 20 nautical miles distant ; beyond 

 that distance the curvature of the earth 

 would prevent a light at this elevation 

 being seen. The light and lens are pro- 

 tected by an outer lantern of glass. 



At the principal stations provision is 

 made either in the tower or in separate 

 buildings for the mechanical equipment 

 connected with light and fog signal, for 

 storage of oil and supplies, for quarters 

 for keepers and their families, boats, etc. 



\'arious materials have been employed 

 in lighthouse construction — stone, brick, 

 iron, steel, concrete, reinforced concrete, 

 and wood ; in new work, however, the 

 latter is now little used because of the 

 desirability of permanency. 



The Lighthouse Service at i)resent 

 owns 1,186 distinct pieces of land; be- 

 sides this, many lights stand in the water, 

 and post lights along the rivers are on 

 temporary sites not purchased. 



WOXOKRFUL SK.V-SWKPT LIGHTIIOUSKS 



Lighthouse construction on the land 

 is usually comixirativcly simple, except 

 when there is flifficulty of access to the 

 site. But often it is important for the 

 protection of shipping that lighthouses 

 be erected either on rocks or reefs ex- 

 posed to the sea or actually in the water, 

 on sand or rock bottom. Such work has 

 called forth the greatest skill of engi- 

 neers. 



Numerous types of construction have 

 been used. Where the foundation is ex- 

 posed, even at the lowest tides, masonry 

 towers have been, with great labor and 

 often danger, fitted to the bed-rock ; 

 otherwise the structure has been erected 

 on iron piles driven, screwed, or pumped 

 into the sand or coral, or on caissons 

 floated to the site and set on the bottom 

 or sunk deeper by the pneumatic process, 

 or by the use of coffer-dams, within 

 which the masonry tower has been 

 erected ; smaller structures have been 

 placed on rip-rap foimdations. 



The earliest exami)le now existing of 

 a sea-swept lighthouse is the beautiful 

 tower of Cordouan. built in 1584 to 161 i. 

 on a rock in the sea at the mouth of the 

 Gironde. on the west coast of France. 

 This lighthouse has since been altered 

 and raised in height, 

 ture was elaborately 

 floor was occupied 

 page 8). 



The most famous of the sea-swept 

 righthouses is the ICddystone. 13 miles 

 from Plymouth harbor. Kngland. This 

 was completed in 1699. after four years 

 of work. During the first year all that 

 was accomplished was drilling 12 holes 

 in the rock and fastening irons in them. 

 This lighthouse, with the keepers and the 

 engineer who built it, disappeared in the 

 great storm of November, 1703. and since 



The original struc- 

 decorated, and one 

 by a chapel (see 



17 



