fore be added to
the total weight carried, which would materially increase the capacity.
Even with the two-passenger load the limit is by no means reached,
but as experiments have gone no further it is impossible to make more
accurate figures.

Average Proportions of Load.

It will be interesting, before proceeding to lay out the dimension
details, to make a comparison of the proportion of load effect with
the supporting surfaces of various well-known machines. Here are the
figures:

Santos-Dumont--A trifle under four pounds per square foot.

Bleriot--Five pounds.

R. E. P.--Five pounds.

Antoinette--About two and one-quarter pounds.

Curtiss--About two and one-half pounds.

Wright--Two and one-quarter pounds.

Farman--A trifle over three pounds.

Voisin--A little under two and one-half pounds.

Importance of Engine Power.

While these figures are authentic, they are in a way misleading, as the
important factor of engine power is not taken into consideration. Let us
recall the fact that it is the engine power which keeps the machine in
motion, and that it is only while in motion that the machine will remain
suspended in the air. Hence, to attribute the support solely to the
surface area is erroneous. True, that once under headway the planes
contribute largely to the sustaining effect, and are absolutely
essential in aerial navigation--the motor could not rise without
them--still, when it comes to a question of weight-sustaining power, we
must also figure on the engine capacity.

In the Wright machine, in which there is a lifting capacity of
approximately 2 1/4 pounds to the square foot of surface area, an engine
of only 25 horsepower is used. In the Curtiss, which has a lifting
capacity of 2 1/2 pounds per square foot, the engine is of 50
horsepower. This is another of the peculiarities of aerial construction
and navigation. Here we have a gain of 1/4 pound in weight-lifting
capacity with an expenditure of double the horsepower. It is this
feature which enables Curtiss to get along with a smaller surface area
of supporting planes at the expense of a big increase in engine power.
Proper Weight of Machine.

As a general proposition the most satisfactory machine for amateur
purposes will be found to be one with a total weight-sustaining power of
about 1,200 pounds. Deducting 170 pounds as the weight of the operator,
this will leave 1,030 pounds for the complete motor-equipped machine,
and it should be e