120 SECTIONAL ADDRESSES. 
frequently many of the important engine-room auxiliaries ; in fact, in 
some vessels practically all the auxiliaries are driven by electric motors. 
There is considerable controversy as to whether these main dynamos 
should be driven by Diesels or steam-engines, and, in the case of steam, 
whether it should not at some stage be drawn from the main engines 
before going to the auxiliary, or passed to the main engine after going 
through the auxiliary, or that the exhaust of the auxiliary be used. for 
heating the feed-water, or a combination of these arrangements. It will 
be interesting to watch the development of that controversy, as on its 
proper solution further economy in fuel consumption will result. Probably 
no one solution will suffice and in Diesel motor-ships we may find the 
auxiliaries driven by steam—e.g. when they are oil tankers requiring the 
steam to heat the cargo oil—while in steam-driven turbine steamers we 
may find the auxiliaries driven by electricity generated by Diesel-driven 
dynamos. 
There are many other pieces of auxiliary machinery connected, for 
example, with refrigeration, lubrication-oil pumps, fuel-oil pumps and 
heaters, pumps for hot and cold water for baths and other sanitary pur- 
poses. When there are automatic self-closing water-tight doors there are 
generally duplicate pumps for supplying high-pressure water to work 
them. It will thus be seen how extensive is now the auxiliary machinery 
in the engine-room. The fuel consumed in developing the power of these 
auxiliaries is now such an important proportion of the total fuel con- 
sumed that their design and installation is becoming, to a certain extent, 
a separate branch of engineering. To show the importance of a thorough 
study of this auxiliary-power question on board ship, I have been informed 
that in a large intermediate passenger-ship the consumption of fuel for 
auxiliaries is reported as exceeding 10 per cent. of the total consumption 
and that 15 per cent. or more is not uncommon in some other vessels. 
The percentage will naturally rise with increased economy of the main 
engines unless the auxiliaries in their turn are made more economical. 
In types of boilers the development has gone from the old box form 
with safety valve opening inwards to prevent them collapsing when cooling, 
to the well-known and most extensively used Scotch marine circular 
boiler with return tubes. But always there were inventors working at the 
water-tube boiler, and several were constructed which proved successful. 
The Haystack was an early example, and those of Yarrow, of Thorny- 
croft, and of Babcock & Wilcox may be named as types. In my own 
experience Yarrow and Babcock have each been used in fast cross-Channel 
steamers with absolute success, and, apart from the great user of water-tube 
boilers, the Royal Navy, water-tube boilers are being used increasingly 
in oversea merchant-ships. And we know that for land stations they are 
in great demand, fitted with mechanical coal-stokers or with pulverised 
coal or oil firing, in units of such enormous size and with steam pressure 
so higt that steam drums have been built’ and used 34 ft. long, 4 ft. 
internal diameter, and 4 in. thick. Shall we see such boilers on board 
merchant-ships ? I have no doubt we shall, though I would not care to 
express any opinion as to the ultimate highest steam-pressure which will 
be used, but 500 lb. is in sight. 
Superheating of steam was early recognised as a very desirable thing, 
but it took many years to produce a reliable superheater, and then there 
were lubrication and other difficulties in reciprocating engines which had 
