THE PROGEESS IN STEAM NAVIGATION. 583 



experiment veiy fur-reaching effects may foiUm. Mr. Parsons him- 

 self has prepared many designs illustrating various applications of the 

 system to seagoing, cross-channel, and special-service vessels. Where 

 shallowness of draft is unavoidal^le, the small diameter of the screws 

 possible with the quick-running turbines is clearlv an important 

 matter. 



COMPARISONS BETWEEN LARGE AND SMALL ^•ESSELS. 



It has been shown that the attainment of very high speeds bv vessels 

 of small size involves many conditions not applicable* to large seagoing 

 steamships. But it is equally true that in many ways the trials of 

 small, swift vessels constitute mod(>l experiments, from which inter- 

 esting information may be obtained as to what would be involved in 

 driving ships of large size at speeds much exceeding any of which we 

 have experience. When the progressive steam trials of such small 

 vessels can be studied side by side with experiments made on models 

 to determine their resistance to various speeds, then the fullest infor- 

 mation is obtained and the best guide to pi-ogi-ess secui-ed. This 

 advantage, as has been said, we owe to William Fi'oude. His contri- 

 butions to the reports of the British Association are classics in the 

 literature of the resistance and propulsion of ships. In IST-A he prac- 

 tically exhausted the subject of frictional resistance so far as it is 

 known, and his presidential address in 1875 dealt fully and lucidly 

 with the modern or stream-line theory of resistance. No doubt there 

 would ])e advantage in extending Froude's experiments on frictional 

 resistance to greater lengths and to ship-shaped forms. It is probalde 

 also that dynamometric determinations of the resistance experienced 

 by ships of modern forms and consideral)le size when towed at various 

 speeds would be of value if they could be conducted. 



These extensions of what Fronde accomplished are not easily ( airied 

 out. and in this country the pressure of work on shipl)uilding for the 

 royal navy has for many years past taxed to th«> utmost limits the 

 capacitv of the Admiralty experimental establishment, so ably super- 

 intended bv Mr. R. E. Froude, allowing little scope for purely scien- 

 tific investigations, and making it difficult to deal with th.> luunerous 

 experiments incidental to the designs of actual ships. Now that Hol- 

 land. Russia, Italy, and the United States have equipped exp.'rin.eiital 

 establishments, while Germany and Franc«> are taking steps in that 

 direction, we may hope for extensions of pur.>ly scientiHc work and 

 additions to our knowledge. In this direction. howev.M-, I an. bonnd 

 to sav that much might be done if experimental estal.lishn.ents <-apabIe 

 of dealing with questions of a general nature relatmg to resistance 

 and propulsion were added to the equipment of some ot onr univer- 

 sities and colleges. Engineering laboratories have been nmlhphed 

 but there is as yet no example of a niodel .-xperimental tank devoted 

 to instruction and research. 



