machine¡¡could¡¡ever¡¡fly£»¡¡would¡¡be¡¡by¡¡propelling¡¡it
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the¡¡atmosphere¡£
LIGHT¡¡MACHINES¡¡UNSTABLE¡£Gradually¡¡the
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flying¡£¡¡The¡¡safest¡¡machines¡¡are¡¡those¡¡which¡¡have
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to¡¡every¡¡caprice¡¡of¡¡the¡¡wind¡£¡¡They¡¡are¡¡notoriously
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THE¡¡APPLICATION¡¡OF¡¡POWER¡£The¡¡thing¡¡now¡¡to
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of¡¡the¡¡supporting¡¡surfaces£»¡¡but¡¡HOW¡¡to¡¡apply
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at¡¡rest¡¡to¡¡one¡¡in¡¡motion£»¡¡and¡¡thereby¡¡get
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in¡¡flight¡£
THE¡¡SUPPORTING¡¡SURFACES¡£This¡¡brings¡¡us¡¡to
the¡¡consideration¡¡of¡¡one¡¡of¡¡the¡¡first¡¡great¡¡problems
in¡¡flying¡¡machines£»¡¡namely£»¡¡the¡¡supporting
surfaces£»not¡¡its¡¡form£»¡¡shape¡¡or¡¡arrangement£»
£¨which¡¡will¡¡be¡¡taken¡¡up¡¡in¡¡their¡¡proper¡¡places£©£»¡¡but
the¡¡area£»¡¡the¡¡dimensions£»¡¡and¡¡the¡¡angle¡¡necessary
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AREA¡¡NOT¡¡THE¡¡ESSENTIAL¡¡THING¡£The¡¡history
of¡¡flying¡¡machines£»¡¡short¡¡as¡¡it¡¡is£»¡¡furnishes¡¡many
examples¡¡of¡¡one¡¡striking¡¡fact£º¡¡That¡¡area¡¡has
but¡¡little¡¡to¡¡do¡¡with¡¡sustaining¡¡an¡¡aeroplane¡¡when
once¡¡in¡¡flight¡£¡¡The¡¡first¡¡Wright¡¡flyer¡¡weighed
741¡¡pounds£»¡¡had¡¡about¡¡400¡¡square¡¡feet¡¡of¡¡plane
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catapult¡£¡¡Motion¡¡having¡¡once¡¡been¡¡imparted¡¡to¡¡it£»
the¡¡only¡¡thing¡¡necessary¡¡for¡¡the¡¡motor¡¡was¡¡to
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There¡¡are¡¡many¡¡instances¡¡to¡¡show¡¡that¡¡when
once¡¡in¡¡flight£»¡¡one¡¡horse¡¡power¡¡will¡¡sustain¡¡over
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THE¡¡LAW¡¡OF¡¡GRAVITY¡£As¡¡the¡¡effort¡¡to¡¡fly
may¡¡be¡¡considered¡¡in¡¡the¡¡light¡¡of¡¡a¡¡struggle¡¡to
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it¡¡may¡¡be¡¡well¡¡to¡¡consider¡¡this¡¡great¡¡force¡¡as¡¡a
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Proper¡¡understanding£»¡¡and¡¡use¡¡of¡¡terms¡¡is¡¡very
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Thus£»¡¡weight¡¡and¡¡mass¡¡are¡¡not¡¡the¡¡same¡£¡¡Weight
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If¡¡projected¡¡through¡¡space£»¡¡a¡¡certain¡¡mass
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or¡¡at¡¡any¡¡altitude¡£
Gravity¡¡has¡¡been¡¡called¡¡weight£»¡¡and¡¡weight
gravity¡£¡¡The¡¡real¡¡difference¡¡is¡¡plain¡¡if¡¡gravity
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Gravity¡¡is¡¡generally¡¡known¡¡and¡¡considered¡¡as¡¡a
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This¡¡is¡¡too¡¡narrow¡£
Gravity¡¡acts¡¡in¡¡all¡¡directions¡£¡¡Two¡¡balls¡¡suspended
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If¡¡one¡¡has¡¡double¡¡the¡¡mass¡¡it¡¡will¡¡have¡¡twice¡¡the
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tripled£»¡¡the¡¡attraction¡¡would¡¡be¡¡increased¡¡six
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attraction¡¡would¡¡be¡¡reduced¡¡to¡¡one¡fourth£»¡¡and
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would¡¡be¡¡only¡¡one¡ninth¡£
The¡¡foregoing¡¡is¡¡the¡¡substance¡¡of¡¡the¡¡law£»
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one¡¡another¡£
To¡¡explain¡¡this¡¡we¡¡cite¡¡the¡¡following¡¡illustration£º
Two¡¡bodies£»¡¡each¡¡having¡¡a¡¡mass¡¡of¡¡4
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only¡¡one¡quarter¡¡of¡¡an¡¡inch£»¡¡and¡¡the¡¡large¡¡one
will¡¡draw¡¡the¡¡other¡¡three¡quarters¡¡of¡¡an¡¡inch£»
thus¡¡confirming¡¡the¡¡law¡¡that¡¡two¡¡bodies¡¡will¡¡attract
each¡¡other¡¡in¡¡proportion¡¡to¡¡their¡¡mass¡£
Suppose£»¡¡now£»¡¡that¡¡these¡¡balls¡¡are¡¡placed¡¡two
inches¡¡apart£»that¡¡is£»¡¡twice¡¡the¡¡distance¡£¡¡As
each¡¡is£»¡¡we¡¡shall¡¡say£»¡¡four¡¡pounds¡¡in¡¡weight£»¡¡the
square¡¡of¡¡each¡¡would¡¡be¡¡16¡£¡¡This¡¡does¡¡not¡¡mean
that¡¡there¡¡would¡¡be¡¡sixteen¡¡times¡¡the¡¡attraction£»
but£»¡¡as¡¡the¡¡law¡¡says£»¡¡inversely¡¡as¡¡the¡¡square¡¡of
the¡¡distance£»¡¡so¡¡that¡¡at¡¡two¡¡inches¡¡there¡¡is¡¡only
one¡sixteenth¡¡the¡¡attraction¡¡as¡¡at¡¡one¡¡inch¡£
If¡¡the¡¡cord¡¡of¡¡one¡¡of¡¡the¡¡balls¡¡should¡¡be¡¡cut£»¡¡it
would¡¡fall¡¡to¡¡the¡¡earth£»¡¡for¡¡the¡¡reason¡¡that¡¡the
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so¡¡much¡¡greater¡¡than¡¡the¡¡force¡¡of¡¡attraction¡¡in
its¡¡companion¡¡ball¡£
INDESTRUCTIBILITY¡¡OF¡¡GRAVITATION¡£Gravity
cannot¡¡be¡¡produced¡¡or¡¡destroyed¡£¡¡It¡¡acts¡¡between
all¡¡parts¡¡of¡¡bodies¡¡equally£»¡¡the¡¡force¡¡being
proportioned¡¡to¡¡their¡¡mass¡£¡¡It¡¡is¡¡not¡¡affected¡¡by
any¡¡intervening¡¡substance£»¡¡and¡¡is¡¡transmitted
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While£»¡¡therefore£»¡¡it¡¡is¡¡impossible¡¡to¡¡divest¡¡matter
of¡¡this¡¡property£»¡¡there¡¡are¡¡two¡¡conditions
which¡¡neutralize¡¡its¡¡effect¡£¡¡The¡¡first¡¡of¡¡these¡¡is
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the¡¡other¡¡hollow£»¡¡but¡¡of¡¡the¡¡same¡¡mass£»¡¡or¡¡density¡£
If¡¡the¡¡cavity¡¡of¡¡the¡¡one¡¡is¡¡large¡¡enough¡¡to¡¡receive
the¡¡other£»¡¡it¡¡is¡¡obvious¡¡that¡¡while¡¡gravity¡¡is¡¡still
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all¡¡points£»¡¡and¡¡radially£»¡¡there¡¡can¡¡be¡¡no¡¡pull¡¡which
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DISTANCE¡¡REDUCES¡¡GRAVITATIONAL¡¡PULL¡£Or
the¡¡balls¡¡may¡¡be¡¡such¡¡distance¡¡apart¡¡that¡¡the¡¡attractive
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an¡¡object¡¡would¡¡not¡¡weigh¡¡anything¡£¡¡A¡¡pound
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the¡¡mass¡¡of¡¡the¡¡other£»¡¡would¡¡be¡¡the¡¡same£»absolutely
without¡¡weight¡£
If¡¡the¡¡object¡¡should¡¡be¡¡far¡¡away¡¡in¡¡space¡¡it
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so¡¡it¡¡will¡¡be¡¡understood¡¡that¡¡position¡¡plays¡¡an
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HOW¡¡MOTION¡¡ANTAGONIZES¡¡GRAVITY¡£The¡¡second
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The¡¡former¡¡is¡¡called¡¡centripetal£»¡¡and¡¡the¡¡latter
centrifugal¡¡motion¡£¡¡Gravity£»¡¡therefore£»¡¡represents
centripetal£»¡¡and¡¡motion¡¡centrifugal¡¡force¡£
If¡¡the¡¡rotative¡¡speed¡¡of¡¡the¡¡earth¡¡should¡¡be¡¡retarded£»
all¡¡objects¡¡on¡¡the¡¡earth¡¡would¡¡be¡¡increased
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A¡¡TANGENT¡£When¡¡an¡¡object¡¡is¡¡thrown¡¡horizontally
the¡¡line¡¡of¡¡flight¡¡is¡¡tangential¡¡to¡¡the¡¡earth£»
or¡¡at¡¡right¡¡angles¡¡to¡¡the¡¡force¡¡of¡¡gravity¡£¡¡Such
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_Fig¡¡1¡£¡¡Tangential¡¡Flight_
TANGENTIAL¡¡MOTION¡¡REPRESENTS¡¡CENTRIFUGAL
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EQUALIZING¡¡THE¡¡TWO¡¡MOTIONS¡£But¡¡now¡¡let¡¡us
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It¡¡is¡¡a¡¡curious¡¡thing¡¡that¡¡neither¡¡Langley£»¡¡nor
any¡¡of¡¡the¡¡scientists£»¡¡in¡¡treating¡¡of¡¡the¡¡matter¡¡of
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_Fig¡£¡¡2¡¡Horizontal¡¡Flight_
All¡¡have¡¡treated¡¡the¡¡subject¡¡as¡¡though¡¡the
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_Fig¡£¡¡3¡£¡¡Lift¡¡and¡¡Drift_
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