TRANSACTIONS OF SECTION G. 845 
and engineering in thirty-five years. The later ship probably requires to carry no 
greater load of coal than, if so great as, her predecessor, although her engine- 
ower is nearly double. The weight devoted to propelling machinery and boilers 
is probably not so great. Thanks to the use of steel instead of iron, and to 
improved structural arrangements, the weight of hull is reduced in comparison 
with dimensions, and a longer ship is produced better adapted to the higher speed. 
Messrs. Laird of Birkenhead, who built three of the Leinster class forty years ago, 
and have built all the new vessels, are to be congratulated on their complete 
success, 
Between such vessels designed for short runs at high speed and requiring 
therefore to carry little coal, while the load carried exclusive of coal is trifling, and 
an ocean-going steamer of the same average speed designed to make passages of 
3,000 miles, there can obviously be little m common. But equal technical skill is 
required to secure the efficient performance of both services. In the cross-Channel 
vessel, running from port to port, and under constant observation, conditions of 
working in engine and boiler rooms, as well as relative lightness in scantlings of 
hull, can be accepted, which would be impossible of application in a sea-going ship. 
These circumstances in association with the small load carried explain the apparent 
gain in speed of the smaller vessel in relation to her dimensions. 
Increase in Size and Speed of Warships. 
Turning from sea-going ships of the mercantile marine to warships, one finds 
equally notable facts in regard to increase in speed, associated with enlargement 
in dimensions and advance in propelling apparatus, materials of construction, 
structural arrangements, and form. 
Up to 1860 a measured-mile speed of 12 to 13 knots was considered sufficient 
for battleships and the largest classes of cruisers. Ati these vessels possessed good 
sail-power and used it freely as an auxiliary to steam, or as an alternative when 
cruising or making passages. 
When armoured battleships were built (1859) the speeds on measured-mile 
trials were raised to 14 or 14} knots, and so remained for about twenty years. 
Since 1880 the speeds of battleships have been gradually increased, and in the 
latest types the measured-mile speed required is 1 knots. 
Up to 1870 the corresponding speeds in cruisers ranged from 15 to 16 knots. 
Ten years later the maximum speeds were 18 to 18} lmots in a few vessels. 
Since then trial speeds of 20 to 283 knots have been attained or are contemplated. 
There is, of course, a radical distinction between these measured-mile perform- 
ances of warships and the average sea-speeds of merchant steamers above described. 
But for purposes of comparison between warships of different dates, measured 
mile trials may fairly be taken as the standard. For long-distance steaming the 
power developed would necessarily be much below that obtained for short periods, 
and with everything at its best. This is frankly recognised by all who are con- 
versant with the warship design, and fully allowed for in estimates of sea-speeds. 
On the other hand, it is possible to point to sea trials made with recent types 
where relatively high speeds have been maintained for long periods. For example, 
the battleship Royal Sovereign has maintained an average speed of 15 knots from 
Plymouth to Gibraltar, and the Renown has maintained an equal speed from 
Bermuda to Spithead. As instances of good steaming by cruisers, reference may 
be made to 60-hour trials with the Terrible when she averaged over 20 knots, and 
to the run home from Gibraltar to the Nore by the Diadem when she exceeded 
19 knots. Vessels of the Pelorus class of only 2,100 tons displacement have made 
long runs at sea averaging over 17 knots, Results such as these represent a sub- 
stantial advance in speed of Her Majesty’s ships in recent years. 
Similar progress has been made in foreign warships built abroad as well as in this 
country. It isnot proposed to give any facts for these vessels, or to compare 
them with results obtained by similar classes of ships in the Royal Navy. Apart 
from full knowledge of the conditions under which speed trials are made, a 
‘mere statement of speeds attained is of no service, One requires to be informed 
