84.4. REPORT—1899, 
accurately respecting the duration of the trial, the manner in which engines and 
boilers are worked, the extent to which boilers are ‘forced,’ or the proportion 
of heating surface to power indicated, the care taken to eliminate the influence of 
tide or current, the mode in which the observations of speed are made, and other 
details, before any fair or exact comparison is possible between ships. For present 
purposes, therefore, it is preferable to confine the illustrations of increase in speed 
in warships to results obtained under Admiralty conditions, and which are fairly 
comparable. 
A great increase in size has accompanied this increase in speed, but it has 
resulted from other changes in modern types, as well as from the rise in speed. 
Modern battleships are of 13,000 to 15,000 tons, and modern cruisers of 10,000 to 
14,000 tons, not merely because they are faster than their predecessors, but because 
they have greater powers of offence and defence and possess greater coal endurance. 
Only a detailed analysis, which cannot now be attempted, could show what is the 
actual influence of these several changes upon size and cost, and how greatly the 
improvements made in marine engineering and shipbuilding have tended to keep 
down the growth in dimensions consequent on increase in load carried, speed 
attained, and distance traversed. 
It will be noted also that, large as are the dimensions of many classes of modern 
warships, they are all smaller in length and displacement than the largest mercan- 
tile steamers above described. There is no doubt a popular belief that the con- 
trary is true, and that warships exceed merchant ships in tonnage This arises 
from the fact that merchant ships are ordinarily described not by their displace- 
ment tonnage, but by their ‘registered tonnage,’ which is far less than their dis- 
placement. As a matter of fact, the largest battleships are only of about two-thirds 
the displacement of the largest passenger steamers, and from 200 to 800 feet 
shorter. The largest cruisers are from 100 to 200 feet shorter than the largest 
passenger steamers, and about 60 per cent. of their displacement. In breadth the 
warships exceed the largest merchant steamers by 5 to 10 feet. This difference in 
form and proportions is the result of radical differences in the vertical distribution 
of weights carried, and is essential to the proper stability of the warships. Here 
we find an illustration of the general principle underlying all ship-designing. In 
selecting the forms and proportions of a new ship, considerations of economical 
propulsion cannot stand alone. They must be associated with other considerations, 
such as stability, protection, and manceuvring power, and in the final result 
eccnomy of propulsion may have to be sacrificed, to some extent, in order to secure 
other essential qualities, 
Advantages of Increased Dimensions. 
Before passing on, it may be interesting to illustrate the gain in economy of 
propulsion resulting from increase in dimensions by means of the following table, 
which gives particulars of a number of typical cruisers, all of comparatively recent 
design :— 
— No. 1 No. 2 No. 3 No. 4 No. 5 
Leastaneety psy) ee amieey 4) | B80 300 360 435 500 
Breadthn(Feck) Meuse 0 ey | BB 43 60 69 71 
Mean draught (feet) . : ~ 13 163 233 244 263 
Displacement (tons) . ‘ . | 1,800 3,400 7,400 |11,000 | 14,200 
Indicated horse-power for 20 knots | 6,000 9,000 {11,000 | 14,000 | 15,500 
Indicated horse-power per ton of 
displacement . : a 5 3°33 2°65 1:48 1:27 1:09 
The figures given are the results of actual trials, and embody therefore the 
efficiencies of propelling machinery, propellers, and forms of the individual ships. 
Even so they are instructive. Comparing the first and last, for example, it will 
be seen that, while the displacement is increased nearly eightfold, the power for 
