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LathamOctober 21； 1909made a short flight； about
11 minutes； in the teeth of a 40 mile gale； at Blackpool；
Eng。 He used an Antoniette monoplane； and the official
report says： 〃This exhibition of nerve； daring and ability
is unparalled in the history of aviation。〃
FarmanOctober 20； 1909was in the air for 1 hour；
32 min。； 16 seconds； travelling 47 miles； 1；184 yards； a
duration record for England。
PaulhanJanuary 18； 190147 1/2 miles at the rate of
45 miles an hour； maintaining an altitude of from 1；000
to 2；000 feet。
Expense of Producing Gas。
Gas is indispensable in the operation of dirigible balloons；
and gas is expensive。 Besides this it is not always
possible to obtain it in sufficient quantities even in large
cities； as the supply on hand is generally needed for
regular customers。 Such as can be had is either water
or coal gas； neither of which is as efficient in lifting
power as hydrogen。
Hydrogen is the lightest and consequently the most
buoyant of all known gases。 It is secured commercially
by treating zinc or iron with dilute sulphuric or
hydrochloric acid。 The average cost may be safely placed
at 10 per 1；000 feet so that； to inflate a balloon of the
size of the Zeppelin； holding 460；000 cubic feet； would
cost 4；600。
Proportions of Materials Required。
In making hydrogen gas it is customary to allow 20
per cent for loss between the generation and the introduction
of the gas into the balloon。 Thus； while the
formula calls for iron 28 times heavier than the weight
of the hydrogen required； and acid 49 times heavier； the
real quantities are 20 per cent greater。 Hydrogen weighs
about 0。09 ounce to the cubic foot。 Consequently if we
need say 450；000 cubic feet of gas we must have 2；531。25
pounds in weight。 To produce this； allowing for the 20
percent loss； we must have 35 times its weight in iron；
or over 44 tons。 Of acid it would take 60 times the
weight of the gas； or nearly 76 tons。
In Time of Emergency。
These figures are appalling； and under ordinary conditions
would be prohibitive； but there are times when
the balloon operator； unable to obtain water or coal gas；
must foot the bills。 In military maneuvers； where the
field of operation is fixed； it is possible to furnish supplies
of hydrogen gas in portable cylinders； but on long
trips where sudden leakage or other cause makes descent
in an unexpected spot unavoidable； it becomes a question
of making your own hydrogen gas or deserting the balloon。
And when this occurs the balloonist is up against
another serious propositioncan he find the necessary
zinc or iron？ Can he get the acid？
Balloons for Commercial Use。
Despite all this the balloon has its uses。 If there is to
be such a thing as aerial navigation in a commercial
waythe carrying of freight and passengersit will
come through the employment of such monster balloons
as Count Zeppelin is building。 But even then the carrying
capacity must of necessity be limited。 The latest
Zeppelin creation； a monster in size； is 450 feet long；
and 42 1/2 feet in diameter。 The dimensions are such as
to make all other balloons look like pigmies； even many
ocean…going steamers are much smaller； and yet its passenger
capacity is very small。 On its 36…hour flight in
May； 1909； the Zeppelin； carried only eight passengers。
The speed； however； was quite respectable； 850 miles
being covered in the 36 hours； a trifle over 23 miles an
hour。 The reserve buoyancy； that is the total lifting
capacity aside from the weight of the airship and its
equipment； is estimated at three tons。
CHAPTER XXII。
PROBLEMS OF AERIAL FLIGHT。
In a lecture before the Royal Society of Arts； reported
in Engineering； F。 W。 Lanchester took the position that
practical flight was not the abstract question which some
apparently considered it to be； but a problem in locomotive
engineering。 The flying machine was a locomotive
appliance； designed not merely to lift a weight；
but to transport it elsewhere； a fact which should be
sufficiently obvious。 Nevertheless one of the leading scientific
men of the day advocated a type in which this； the
main function of the flying machine； was overlooked。
When the machine was considered as a method of transport；
the vertical screw type； or helicopter； became at
once ridiculous。 It had； nevertheless； many advocates
who had some vague and ill…defined notion of subsequent
motion through the air after the weight was raised。
Helicopter Type Useless。
When efficiency of transport was demanded； the helicopter
type was entirely out of court。 Almost all of
its advocates neglected the effect of the motion of the
machine through the air on the efficiency of the vertical
screws。 They either assumed that the motion was
so slow as not to matter； or that a patch of still air
accompanied the machine in its flight。 Only one form of this
type had any possibility of success。 In this there were
two screws running on inclined axlesone on each side
of the weight to be lifted。 The action of such inclined
screw was curious； and in a previous lecture he had
pointed out that it was almost exactly the same as that
of a bird's wing。 In high…speed racing craft such inclined
screws were of necessity often used； but it was
at a sacrifice of their efficiency。 In any case the efficiency
of the inclined…screw helicopter could not compare
with that of an aeroplane； and that type might be
dismissed from consideration so soon as efficiency became
the ruling factor of the design。
Must Compete With Locomotive。
To justify itself the aeroplane must compete； in some
regard or other； with other locomotive appliances； performing
one or more of the purposes of locomotion more
efficiently than existing systems。 It would be no use
unless able to stem air currents； so that its velocity must
he greater than that of the worst winds liable to be encountered。
To illustrate the limitations imposed on the
motion of an aeroplane by wind velocity； Mr。 Lanchester
gave the diagrams shown in Figs。 1 to 4。 The circle
in each case was； he said； described with a radius equal
to the speed of the aeroplane in still air； from a center
placed 〃down…wind〃 from the aeroplane by an amount
equal to the velocity of the wind。
Fig。 1 therefore represented the case in which the
air was still； and in this case the aeroplane represented
by _A_ had perfect liberty of movement in any direction
In Fig。 2 the velocity of the wind was half that of the
aeroplane； and the latter could still navigate in any
direction； but its speed against the wind was only one…
third of its speed with the wind。
In Fig。 3 the velocity of the wind was equal to that
of the aeroplane； and then motion against the wind was
impossible； but it could move to any point of the
circle； but not to any point lying to the left of the tangent
_A_ _B_。 Finally； when the wind