Mr. Calvert urged that more attention should be devoted to studying
the relative values of different portions of the propeller.
The sitting was then suspended. In the afternoon, as we have already
stated, the members visited the steamship Germanic on the invitation
of Messrs. Ismay, Imrie & Co., subsequently proceeding to Messrs. Cope
Brothers' tobacco works, and thence to the exhibition, where the
dinner of the Institution took place in the evening.
On Friday morning no paper was read; some official business was
transacted, and this being done, the discussion on Mr. John's paper
was resumed.
Mr. Biles remarked that there were many advantages in the use of twin
screws which had not been sufficiently taken into account. When a ship
with twin screws was being handled in dock there was greater
maneuvering power, and therefore less liability for the ship to come
in contact with the walls, although, if she did so, there would be
greater probability of damage to the propellers. He thought means
could be easily devised of protecting the screws when the ship was in
dock. Another of the incidental advantages connected with twin screws
was that smaller engines and smaller propellers were required, and
therefore they might run them at a higher speed. They would also get
lighter machinery with twin screws, and there would be less liability
to have bad castings and forgings in the smaller engines, and of
course the cost would be less.
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