will give 50 horsepower. Generally speaking, eight cylinders, the bore,
stroke and speed being the same, will give double the power that can be
obtained from four, but this does not always hold good. Just why this
exception should occur is not explainable by any accepted rule.

Horse Power and Speed.

Speed is an important requisite in a flying-machine motor, as the
velocity of the aeroplane is a vital factor in flotation. At
first thought, the propeller and similar adjuncts being equal, the
inexperienced mind would naturally argue that a 50-horsepower engine
should produce just double the speed of one of 25-horsepower. That
this is a fallacy is shown by actual performances. The Wrights, using a
25-horsepower motor, have made 44 miles an hour, while Bleriot, with a
50-horsepower motor, has a record of a short-distance flight at the rate
of 52 miles an hour. The fact is that, so far as speed is concerned,
much depends upon the velocity of the wind, the size and shape of the
aeroplane itself, and the size, shape and gearing of the propeller. The
stronger the wind is blowing the easier it will be for the aeroplane
to ascend, but at the same time the more difficult it will be to make
headway against the wind in a horizontal direction. With a strong head
wind, and proper engine force, your machine will progress to a certain
extent, but it will be at an angle. If the aviator desired to keep
on going upward this would be all right, but there is a limit to the
altitude which it is desirable to reach--from 100 to 500 feet for
experts--and after that it becomes a question of going straight ahead.

Great Waste of Power.

One thing is certain--even in the most efficient of modern aerial motors
there is a great loss of power between the two points of production and
effect. The Wright outfit, which is admittedly one of the most effective
in use, takes one horsepower of force for the raising and propulsion of
each 50 pounds of weight. This, for a 25-horsepower engine, would give
a maximum lifting capacity of 1250 pounds. It is doubtful if any of
the higher rated motors have greater efficiency. As an 8-cylinder motor
requires more fuel to operate than a 4-cylinder, it naturally follows
that it is more expensive to run than the smaller motor, and a normal
increase in capacity, taking actual performances as a criterion, is
lacking. In other words, what is the sense of using an 8-cylinder motor
when one of 4 cylinders is sufficient?