The morning news. [volume] (Savannah, Ga.) 1887-1900, 1897-07-25

at the required angle. The guide blades
are so shaped as to effect this purpose.
In order to use steam eGor omically, it
must be worked extensively, and it is this
problem which Mr.. Parsons has succeeded
in solving by the following ingenious de-
vice. AS the steam does work it necessa-
rily increases in volume, and loses pro-
portionately in pressure. In order to ac-
commodate the increased volume, addi-
tionai blade area is given by gradually
increasing the annulat space and the size
of the blades. In this way we have the
analogue Of the two diameter cylinders of
the ordinary compound engine, but in he
turbine the action is more perfect, because
it is gradual and continuous. and, there
fore, is capable of being carried much
further. AS an instance of this ii may be
stated that in the Turbinia's engine the
steam is expanded 170-fold as against To-
fold in ordinary triple expansion engines.
The Turbinia has three turbines, which
drive directly three propeller shafts. In
order to work these motors most efficient
ly high speed of revolutions is required.
The revolutions at full speed are 2,100,
rate Of turning which, it is needless to say,
has never before been attempted in any
vessel. This high speed precludes the use
of propeller of ordinary dimensions, and
to obtain the necessary grip of the water
three screws are placed on each shaft of
nine in an. The propeller ques ton in con-
nection with the boat is one of remarkable
interest, and Mr.. Parsons experiments
have already led to a good deal of light be-
ing thrown on a very obscure detail of
marine engineering, more especially in re-
gard to cavitation. 1t would, however, not
be possible to enter into the subject here.
1t will be sufficient to say that the propel-
Ter difficulty has been so effectively over
come, or perhaps one should say masked
as to allow the remarkable speed before
a1 - INA NJ
is chiefly due to the high efficacy and
lightness of the machinery-that is to say
that Parsons turbine will get more
power from the steam generated by a
given boi4er as compared to an ordinary
marine engine, although it may be con-
sderably lighter than the latter. The to-
tai weight of the Turbinia's engines is
three tons thirteen hundredweight, and
they develop 2,10O indicated horse power
as determined by Prof. j. A. Ewing, f. R.
s. Ordinary navy engines of the torpedo
vessel class would weigh probably fifteen
to twenty tons. The boiler of the Tur-
binia is of the now well-known water-tube
type, and does not call for special notice;
there are two cylindrical condensers of
ordinary design. The hull is modelled on
lines usual with torpedo craft. During
last week the boat made sundry runs in
the Solent at full power, and a number of
naval officers and admiralty officials took
the opportunity OF getting some expert
ence of the vessel. on Thursday she made
a run from Cowes to Portsmouth at a
| speed which was estimated at between 81
| and 80 knots. AS might be anticipated
from the nature of the engines, there was
| almost an entire absence of vibration.
Owing to difficulty in reversing the steam
| turbine the Turbnia will go astern at a
| speed of about three knots only. To over
come this, a special reverse turbine is to
be added.