218 



♦ KNOWLEDGE ♦ 



[March 13, 1885. 



The pontoon cannot elevate the rails on its deck above 

 vrhat would be a prolongation of the rails on shore, because 

 of the heads of the anchor-bolts or guiding-rods, and these 

 ■will also prevent any tipping of the pontoon when the ship- 



tracks each of 4 ft. 8J, in. Ships themselves are girders, 

 and must of a necessity be so, from stem to stern, because 

 in the tempestuous seas in which they are designed to 

 roam, the one part is constantly being called upon to 



Fig. 2. Elevation of the Adjastincj of the Screw Standard for 

 BnpportiDg the vessel on the pontoon. 



Fig. 4. Perspective view of Floating Pontoon, showing the nnmber 

 of hydraulic jacks used. 



■/ ;l'x\ 



Fig. 3. Sectional Elevation of Pontoon and Eailway Cradle. 



Fig. 5. Details of screw standards. 



burdened cradle is moving oil'. The c;irriage with its 

 cradle, which comes np upon the submerged deck, is calcu- 

 lated to hold a ship even more firmly than the launching- 

 cradle used at the shipyards, with its shores and stays. 

 This cariiage moves upon six rails, three standard gauge 



support the other; now her bow projects over a great 

 billow with nothing under to support it, and again she is 

 poised upon a huge wave, leaving the midship section to 

 support iu a great measure both the bow and the stern ; 

 and were she not constructed as a girder fore and aft, 



