of cost an aerial line would cost a tithe
of the ordinary railway. It has neither right of way, road bed,
rails, nor telegraph system to maintain, and if the average flyer
seems to cost amazingly it still foots up less than one fifth the
cost of a modern locomotive though its period of service is much
shorter.

Just at the present time aircraft costs are high, based on
artificial conditions in the market. Their construction is a new
industry; its processes not yet standardized; its materials still
experimental in many ways and not yet systematically produced. A
light sporting monoplane which superficially seems to have about
$250 worth of materials in it--exclusive of the engine--will cost
about $3000. A fighting biplane will touch $10,000. Yet the latter
seems to the lay observer to contain no costly materials to justify
so great a charge. The wings are a light wooden framework, usually
of spruce, across which a fine grade of linen cloth is stretched.
The materials are simple enough, but every bit of wood, every screw,
every strand of wire is selected with the utmost care, and the
workmanship of their assemblage is as painstaking as the setting of
the most precious stones.

[Illustration: (C) International Film Service.

_A German "Gotha"--their Favorite Type._]

"REMEMBER THE LEAST NEGLIGENCE MAY COST A LIFE!" is a sign
frequently seen hanging over the work benches in an airplane
factory.

When stretched over the framework, the cloth of the wings is
treated to a dressing down of a preparation of collodion, which in
the jargon of the shop is called "dope." This substance has a
peculiar effect upon the cloth, causing it to shrink, and thus
making it more taut and rigid than it could be by the most careful
stretching. Though the layman would not suspect it, this wash alone
costs about $150 a machine. The seaplanes too--or hydroaeroplanes as
purists call them--present a curious illustration of unexpected and,
it would seem, unexplainable expense. Where the flyer over land has
two bicycle wheels on which to land, the flyer over the sea has two
flat-bottomed boats or pontoons. These cost from $1000 to $1200 and
look as though they should cost not over $100. But the necessity of
combining maximum strength with minimum weight sends the price
soaring as the machine itself soars. Moreover there is not yet the
demand for either air-or seaplanes that would result in the division
of labour, standardization of parts, and o