THE PRO(}KESS IN STEAM NAVIOATTON. 587 



rule, the ^'inventors" have no intimate knowledo-e of the subject they 

 treat, \Yhich is confessedly one of o-reat difficulty. When experiments 

 are adduced in support of proposals they are almost always found to 

 be inconclusive and inaccurate. More or less mathematical" demonstra- 

 tions lind favor with other inventors, hut they are not more satisfac- 

 tory than the experiments. An air of o-reat precision conunonly 

 pervades the statements made as to possible increase in efficiency ov 

 speed. I have known cases where probable spe^eds with novel propel- 

 lers have been estimated— or guessed— to the third place of deeimals. 



In one instance a trial was made with the new propeller with the 

 result that, instead of a g-ain in efficiency, there was a serious loss of 

 speed. Very few of the proposals made have merit enough to be 

 subjected to trial. None of them can possibly give the l)enefits 

 claimed. It need hardly be added that, in speaking thus of so-called 

 "inventors," there is no suggestion that improvement has reached its 

 limit, or that further discovery is not to be made. On the contrary, 

 in regard to the forms of ships and propellers, continuous investiga- 

 tion is proceeding, and successive advances are being made. From 

 the nature of the case, however, the difficulties to be surmounted 

 increase as speeds rise, and a thorough mastery of the past history 

 and present condition of the problems of steamship design and pro- 

 pulsion is required as a preparation for fruitful work in the natui-c of 

 further advance. 



It would be idle to attempt any predictions as to the characteristic 

 features of ocean navigation sixty years hence. Radical changes may 

 well be made within that period. Confining attention to the inune- 

 diate future, it seems probable that the lines of advance which I have 

 endeavored to indicate will remain in us(\ Further reductions may 

 be anticipated in the weight of propelling apparatus and fuel in pro- 

 portion to the power developed; further savings in the weight of the 

 hulls, arisino- from the use of stronger matei-ials and inii)roy«"d struc- 

 tural arrangements, improvements in form, and enlargement in dunen 

 sions. If greater drafts of water can be made possible, so much the 

 better for carrying power and speed. For merchant yessels com- 

 mercial considerations nuist govern the tinal decisions; foi- war ships 

 the needs of naval warfare will prevail. 



It is certain that scientific methods of procednre and the use of 

 model experiments on ships and propellers will lu'coine of increased 

 importance. Already avenues for further progress are being op<'n."(l. 

 For example, the use of water-tube boilers in recent cruisers aful battle 

 ships of the roval navy has resulted in saying one-third of tlH> weight 

 necessary with cylindrical boilers of the ordinary type to obtam the 

 same power, with natural draft in the stoke holds. Diti.'ren.-es of 

 opinion prevail as to the policy of adopting particular types of water- 

 tube boilers; but the weight of opinion is distinctly u. favor ..t some 



