570 THE PROGRESS IN STEAM NAVIGATION. 



proportionatoly us licavv :is tho.so in u.se sixty yoars aoo. thoy would 

 have weighed about 14,000 tons. In other words, uiaeliinery, l)oilcrs, 

 and coal would have exceeded in weight the total weight of the Cani- 

 punia as she floats to-dtiy. There could not be a more sti'iking illus- 

 tration than this of the close relation between improvements in marine 

 engineering and the development of steam navigation at high speeds. 



E([ually true is it that this development could not have been accom 

 plislicd but for the use of improved materials and structural arrange- 

 ments. Wood as the principal material for the hulls of high-powered 

 swift steamers imposed limits upon dimensions, proportions, and 

 powers which would have ])een a bar to progress. The use of iron 

 first, and since of steel, removed those limits. The percentage of the 

 total displacement devoted to hull in a modern Atlantic liner of the 

 largest size is not much, if at all, greater than was the corresponding 

 })crcentage in the wood-built Bi'itannia of 1840, of one-third the 

 length and one-tenth the total weight. Nor nmst it l)e overlooked 

 that with increase in dimensions have come considerable improve- 

 ments in form favoring economy in propulsion. This is distinct from 

 the economy resulting from increase in size, which Brunei appreciated 

 thoroughly half a century ago when he designed the (rreat Britain 

 and the (rnut Kaxtttm. 



The importance of a due relation between the lengths of the '"en- 

 trance and run"* of steamships and their intended maxinnmi speeds, 

 and the advantages of greater length and fineness of form as speeds 

 are increased, were strongly insisted upon by Scott liussell and Froude. 

 Naval architects, as a matter of course, now act upon the principle, so 

 far as other conditions p(>rmit. For it nuist never l)e forgotten that 

 economy of propulsion is only one of man}' desiderata which must be 

 kept in view in steamship design. Structural weight and strength, 

 seaworthiness, and stability all claim attention and may necessitate 

 modifications in dimensions and form which do not favor the maxi- 

 mum economy of propulsion. Increase in length and weight have 

 largely assisted the marvelous regularity of service now attained on 

 the longest passages by swift steamships. Even the largest vessels at 

 tiuK^s have to yield to the forces of nature displayed in wind and sea; 

 but these conditions are more rarely reached in the longer and 

 heavier ships. 



SWIFT PASSENGER STEAMERS FOR LONG VOYAGES. 



Changes similar to those described for the trans-Atlantic service have 

 been in progress on all the great lines of ocean traffic. In many 

 instances increase in size has been due not only to increase in speed, 

 but to enlarged carrj-ing power and the extension of the lengths of 

 voyages. No distance is now found too great for the successful work- 

 ing of steamships, and the sailing fleet is rapidly diminishing in 



