planes, and having all the screw slip in the line of flight,
and carrying slow and heavy engines.

That as a result of these conclusions, the supporting and propelling
power should be expressed in the rotation of screws combining both
functions, the position of whose planes of rotation to a fixed
horizontal line of direction determines the progress and speed of
machine upon other lines.

That the whole weight carried by the screws should be at all times
exactly below the center of gravity of the plane of support, whether
it be horizontal or inclined.

That while the _permanently_ positioned weight, such as the engines,
frame, holding screws, etc., may be rigidly connected to or around the
screw plane of support, the variable positioned weight, such as the
passenger and the car, should be connected by a _flexible joint_ to
the said plane of support.

Consequently, the car may oscillate without altering its weight
position under center of supporting plane, thus avoiding an
involuntary alteration of speed or direction of flight.

That to steer a machine so constructed, it is merely necessary to move
the point of attachment of car to _machine_ proper, out of the center
of plane of support in the desired direction, and thus cause the plane
of support or rotation of propellers to incline in that direction.

That the reservoir of power, the boiler, etc., should be placed in the
_car_, and steam carried to engines through joint connecting car with
machine.

That at present material exists, and power also, of sufficient
lightness and strength to admit of a machine construction capable of a
limited successful flight in any fair wind and direction.

That such _machine_ once built, the finding of a _power_ for long
flights will be easy, if not already close at hand in _electricity_.

That the _easiest_ design for such _actual machine_ should be adopted,
leaving the adaptation of the principles involved to the making of
more perfect machines, to a time after the success of the _first_.

That such design may be a propeller, and its engine at each end of a
steel frame tube, supporting tube horizontally, a car to be supported
by a universal joint from center of said tube, and the joint apparatus
movable along the tube or a short distance transverse to it, to alter
position of center of gravity.

That the machine so built might traverse the water as well as air.

* * * * *

THE LONGH