THE EVOLUTION OF THE LIGHTSHIP. 109 



The French authorities appear to have been cautious in adopting iron for 

 Hghtship construction. It was not until 1891 that a vessel, the "new" Ruytingen, 

 was built entirely of this metal. It was 30 meters in length, 7.82 meters in breadth 

 at the deck, and of 338 tons displacement. A distinctive feature of design is the use 

 of cast-iron bilge keels, which serve their usual function and have a secondary 

 steadying effect due to the inertia of their "winged out" position. 



For a number of years from the dates just noted, both composite and wooden 

 construction were in common use. Experience with the metal of the composite 

 vessels taught the crews what care was necessary for its satisfactory preservation, 

 and by 1900 authorities had generally accepted steel as the only material suitable 

 for lightships at important stations. There were still, of course, some advocates of 

 wood, and, as recently as 1902, a first-class U. S. lightship was constructed of 

 wood and stationed off the Maine coast. This lightvessel. No. 74, is 118 feet long, 

 28 feet 6 inches beam, 14 feet 7 inches deep, and of 495 tons displacement. Two 

 cylindrical boilers and a single cylinder propelling engine of 380 indicated horse- 

 power were fitted to make the vessel independent of a convoy, and in all fittings 

 and equipment no expense was spared to produce the best results. The framing 

 of the hull was of the best selected white oak and the planking of yellow pine; 

 the hull is copper fastened generally, and sheathed to a point well above the water 

 line. 



The lightship of steel construction, as illustrated by a recently completed vessel 

 for the U. S. Service, Lightvessel No. 94, now stationed on the Frying Pan Shoals, 

 N. C, is fully described and illustrated at the close of this paper. 



A second practical feature of design, which has greatly increased the gen- 

 eral efficiency of the lightship, is propelling machinery. This alone enables the 

 ship to proceed to its station without a convoy, and also to ease oft' the strain on 

 its moorings by steaming up into a heavy storm ; or to return to and stajid by the 

 station marking buoy in case the moorings are actually carried away. An earnest 

 recommendation that vessels be equipped with propelling machinery was made 

 to the British "Royal Commission on Lighthouses" as early as i860. It appears 

 however, that the proposition received but little attention, and I find no evidence 

 that lightships were so equipped before 1891. At that date three second-class 

 lightships were built for the U. S. Service, Nos. 55, 56 and 57, 90 feet by 20 feet 

 by 9 feet and 130 gross tons, and fitted with propelling machinery. This installa- 

 tion was of but little power, consisting of but a single non-condensing engine, with 

 a cylinder of 14 inches diameter and 16 inches stroke, and one marine fire-box 

 flue boiler carrying 100 pounds pressure. But it was a proof of utility, and now 

 many vessels of size, on important exposed stations, are fitted with compound en- 

 gines and one or two boilers. 



The propelling plant of a first-class U. S. lightvessel in present service con- 

 sists of a vertical, surface condensing, compound engine, with cylinders 16 inches 

 and 31 inches in diameter, and a stroke of 24 inches, driving a four-bladed propel- 

 ler 7 feet 9 inches in diameter, and of 10 feet pitch. Steam is supplied at 100 



