New-York tribune., 1900-07-15
ELECTRICALLY PROPELLED SHIPS.

The practicability of using electricity TO pro-
pei ships is discussed in the July number of
Marine Engineering" by William +. Durand.
The immediate purpose of his paper is TO re-
view certain utterances of Mr.. Tesla in the June
Century" But independently of that feature
the matter possesses much interest. Besides,
Mr. Durand treats it in such cogent and con
vincng fashion that his views deserve wide
publicity. So numerous and advantageous are
the applications of electricity which have al
ready been made TO industry that those who
are not experts in electrical science may well
believe that anything is possible with it. Ger
tainly it's scrviceability in marine transporta-
ton is the more credible because of the won
during the last ten years.
Mr. Durand devOtes no attention to storage
batteries although that apparatus has been eX-
tenSively used in combination with electric mo-
tors on launches for several years. But the pos
sihili5y of running boat for two or three hours
without obtaining fresh charge does not de
mOnstrate the feasibility of doing SO for two
hundred or two hundred and fifty 1t has been
estimated that accumulators capable of supply
ing the power required to prOpel a ship across
the Atlantic would weigh much as the vessel
itself if not more. Hence there is little hope in
that direction
considers is that the steam engines of an ocean
liner. instead of exerting their power directly
on the propeller shaft, shall be employed to
drive dyuamos, that the current thus generated
shall be made to run electric motors, and that
the latter shall turn the screws Mr. Durand
first points out that this series of operations
involves two transformations of cnergy-Of
power into electricity and electricity into power
and that these would entail a loss of from 10
TO i per cent. Hence it is more economical TO
connect the prime mover directly with the
mechanism 10 be moved. Even though some
specially improved engine were employed, the
rule would still hold good. In the second place,
the intermediate electrical machinery would add
materially to the of the equipment, and
also to tle space occupied and the weight Thus
there would be less room for cargo; or. if the
same cargo were carried then the ship would
sink deeper in the water and travel more
slowly. This in turn means greater fuel con
sumption. In more ways than one, then. the
plan is open TO objection without offering com
pensating advantages.
In single phrase of his Century article
Mr.. Tesla suggested that gas engines might he
used instead of steam to drive the dynamos.
But Mr.. Durand shows that this scheme still
further embarrasseS the question. In proper
ton To the power developed n gas engine is
y
acteristic would not he n fault on land-in an
electric light station, for instance. But at sea
the case is different. Again. no gas engine of
more than a few hundred horse power has yet
been constructed and Mr.. Durand asks who
would be willing to design and guarantee the
performance of a pair of 10000 horse power gas
engines of this type. But, supposing that the
engines were provided, il would he necessary 10
have a supply Of gas. Would this be manu-
faCturod on shipboard from coal? If so,
special plant must be taken along, adding once
more 10 the weight of the equipment Gasolene
might be employed. in automobiles; but it
would prove altogether too expensive. The gas
engine is unquostonably 4 good thing; but there
are limits TO IT'S availability there are 10 that
of electricity. And il is TO be feared that Mr..
Tesla is either too sangune or else has been "A
little unCuarded in his expressions regarding
them both.