ON NA VAL ARCHITECTURE. 297 



thicknesses on such iron frames, but with no iron skin. The inner 

 thickness of wood is secured to the frames by Muntz metal screw bolts, 

 and the outer thickness to the inner by copper bolts, and the whole is 

 then sheathed with copper. There is an internal keel, stern, and stern 

 post of iron and also external ones of wood. This system of construc- 

 tion is but little used in merchant ships. 



Some of the ships having iron skins are simply protected by a paint 

 composition. That of Dr. Sim, among others, gives excellent results 

 as to preservation of the iron, and very good results as to cleanliness. 



In order to preserve a clean skin and maintain speed longer that can be 

 expected with paint upon the iron, it is the practice in some cases to 

 sheathe the outside either with copper or zinc. If copper is used, two 

 thicknesses of wood sheathing are wanted between the iron and the copper, 

 the outer one fastened with brass, and the stem and stern-post need to be 

 also of brass. There is still some risk, without careful workmanship, 

 of injury to the iron by galvanic action. To avoid this, and to simplify 

 and cheapen the work, zinc has been employed with only one thickness 

 of wood between, and iron fastening. It appears, so far as experiments 

 have gone, to preserve the iron perfectly, to keep as free from weed and 

 shell-fish as copper ; to be as readily cleansed or washed down as 

 copper, but to oxidate with a somewhat rougher surface and therefore 

 with more friction. 



I would call attention to the life-saving apparatus exhibited, especially 

 to that of the National Life Boat Institution, and Mr. White's boat 

 bridge, as fitted in the troopship " Orontes." 



In conclusion, I would refer to what is being done in training naval 

 architects and marine engineers in England. 



In 1 864 the Education Department, at the instance of the Institution 

 of Naval Architects, established the Royal School of Naval Architects 

 at South Kensington. This school existed nearly nine years and 

 entered 119 naval architects and marine engineers, of whom thirty- 

 eight were private and eighty-one Admiralty students. In 1873 it 

 transferred twenty-four of its students to the Royal Naval College at 

 Greenwich, and ceased itself to exist. The entries at the Royal Naval 

 College between October, 1873, and the present date have been, 

 including those transferred from South Kensington, twenty-four naval 

 architects and 113 marine engineers. 



