There is soon to set sail from London for New York a new and
remarkable little steamer of 70 tons gross burden, named the
Anthracite, designed to exhibit the advanced engineering ideas of
Mr. Loftus Perkins, of England. The distinctive peculiarities of this
steamer are the very high steam pressure that she carries--350 to 500
lb. to the square inch, and the small consumption of fuel--one pound
of coal per hour per horsepower. A trial trip of this new little boat
was lately made of 46 miles, during which 350 lb. steam pressure was
steadily maintained, 132 revolutions per minute of propeller, and a
speed of eight knots per hour. Other vessels, some of larger size than
the above, have been built on the Perkins system, and are running
in England. One of them, the yacht Emily, carries 500 lb. boiler
pressure. Most of our readers are familiar with Mr. Perkins' system,
which has been fully described in our columns. Those who may wish to
refer thereto are directed to an interesting article by Mr. Perkins,
with engravings, published in the SCIENTIFIC AMERICAN SUPPLEMENT, No.
81, July 21, 1877; also to the description of the steam ferry boat,
run on this principle, given with three pages of engravings in our
SUPPLEMENT No. 217.
Engineering theory and practice have for a long time plainly pointed
to high steam pressures as one of the surest ways to economy of fuel.
Twenty five years ago our ocean steamers carried only 16 lb. pressure
to the inch, and burned 5 to 6 lb. of coal per hour per horse power.
To-day they are carrying 75 lb. pressure, and burning 21/2 to 3 lb. of
coal per hour per horse power.
In 1840 the Britannia, one of the finest steamers of the Cunard line
plying between this country and England, burned 5,291 lb. of coal for
each ton of paying freight she carried, her speed, then considered
fast, being 81/2 knots per hour. In 1877 the Britannic, speed 15.6 knots
per hour, burned only 551 lb. of coal per ton of freight carried.
Although our present steamers are making fast time and are very
economical as compared with earlier vessels, still it is a lamentable
fact that on the largest and finest of them, furnished with all the
latest improvements and best appliances to secure economy, worked by
the most careful and intelligent engineers, we succeed in putting
into our steam only about one tenth of the heat realized in our
boiler fire, the remaining nine-tenths of the heat being lost. Only in
proportion as we make our steam hotter, and expanding it more, shall
we economize in fuel. In this respect the voyage of the Anthracite is
designed by her owners, we presume, to be an eye-opener for steamboat
owners, not only in this country but throughout the world. If a little
bit of a boat like this, 84 feet long, 16 feet beam, and 10 feet deep,
can carry its own coal and water across the Atlantic, with a pressure
of 350 to 500 lb. to the inch, and on one pound of coal per horse
power, the natural inference is that our great steamers, when fitted
with the same system, will realize far better results. The change from
three pounds of coal to one pound per horse power means a shaving of
two thirds in the coal bill, which is always an enormous item in the
expenses of large boats. We ought to add that another peculiarity of
the Anthracite is that she uses the same boiler water over and over,
only a trifle of fresh water being supplied to make good the slight
waste. Our New York steamboat men, who have to pay so dear for Croton
water, will be likely to examine the water tank of the Anthracite with
interest.
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