192 THE BEST ARRANGEMENT FOR COMBINED 
This arrangement admits of a cooler engine room than can be obtained 
where the hottest parts of the machinery are in the wings and, in most 
cases, under deck. In the arrangement proposed by the writer the hottest 
parts of the machinery are directly under the casing that leads up through 
all the decks to the open air above. 
There are certain objections which will be brought against my arrange- 
ment and some of these are important and have been carefully considered. 
It may be asked, why sacrifice the maneuvering power of two propellers on 
reversing engines for that of one? In reply to this it is claimed that the 
advantage of a simpler and cheaper arrangement with the most effective 
propeller on the center line of the ship and the promise of better economy, 
should outweigh any possible advantage for maneuvering that the twin 
screw has over the single screw ship. It is quite possible that this advantage 
may be over-rated. The writer, from his office window, has the opportunity 
to watch the docking of two steamships once aweek. ‘They are sister ships 
in every respect except that one is a single screw while the other has 
twin screws. Each vessel is of 5,000 horse-power and 400 feet long on the 
water line. The dock that these vessels land at is across the tide which 
runs either one way or the other with the flood or ebb. ‘The writer is 
interested in these vessels, both having been built under his supervision, and 
yet after careful observation, extending over three years, he has not been 
able to observe any marked advantage that the one has over the other in 
making a landing at the dock, no assistance is ever required by either of 
them. ‘Two days ago he timed the single screw vessel and found that the 
time consumed from being abreast of the end of the dock to being moored 
alongside was just 6.5 minutes. Ina larger ship, the turning effect of running 
the screws in opposite directions would bestill less than intheshipsmentioned 
above. The backing power of the single large propeller on the center line 
when the engine exhausts to the condenser would be ample for all purposes. 
Another objection that might be raised to the arrangement advocated 
by the writer, is that a breakdown of the reciprocating engine would deprive 
the ship of any backing power. This objection must be admitted, yet from 
the simple construction of the proposed reciprocating engine, a breakdown 
involving the stopping of the engines for good seems rather a remote possi- 
bility and, if it should happen, the turbines could keep the vessel going 
ahead until she could arrange by wireless for assistance in making port. 
These are the two principal objections that can be advanced against 
the arrangement that the writer proposes, while, if he is right in the claim 
that the turbine can show a higher efficiency than the reciprocating engine 
to a point much higher in the expansion curve than 9 or 10 pounds absolute, 
then the arrangement he proposes would give a better combined economical 
