aeroplanes- 第24部分

it　is　not　at　all　an　easy　problem　for　an　aviator　to

do　work　which　is　commensurate　with　the　risk

involved。　The　range　is　generally　too　great；　the

necessity　of　swift　movement　in　the　machine　too

speedy　to　assure　accuracy；　and　to　attack　a　foe　at

haphazard　points　can　never　be　effectual。　Even

the　slowly…moving　gas　fields；　like　the　Zeppelin；

cannot　deliver　bombs　with　any　degree　of　precision

or　accuracy。



BOMB…THROWING　TESTS。It　is　interesting；　however；

to　understand　how　an　aviator　knows　where

or　when　to　drop　the　bomb　from　a　swiftly…moving

machine。　Several　things　must　be　taken　into　consideration；

such　as　the　height　of　the　machine　from

the　earth；　its　speed；　and　the　parabolic　curve　that

the　bomb　will　take　on　its　flight　to　the　earth。



When　an　object　is　released　from　a　moving　machine

it　will　follow　the　machine　from　which　it　is

dropped；　gradually　receding　from　it；　as　it　descends；

so　that　the　machine　is　actually　beyond

the　place　where　the　bomb　strikes　the　earth；　due

to　the　retarding　motion　of　the　atmosphere　against

the　missile。



The　diagram　Fig。　90　will　aid　the　boy　in　grasping

the　situation。　A　is　the　airship；　B　the　path

of　its　flight；　a　the　course　of　the　bomb　after　it

leaves　the　airship；　and　D　the　earth。　The　question

is　how　to　determine　the　proper　movement

when　to　release　the　bomb。



METHOD　FOR　DETERMINING　MOVEMENT　OF　A

BOMB。Lieut。　Scott；　U。　S。　A。；　of　the　Coast　Survey

Artillery；　suggested　a　method　for　determining

these　questions。　It　was　necessary　to　ascertain；

first；　the　altitude　and　speed。　While　the　barometer

is　used　to　determine　altitudes；　it　is

obvious　that　speed　is　a　matter　much　more　difficult

to　ascertain；　owing　to　the　wind　movements；

which　in　all　cases　make　it　difficult　for　a　flier　to

determine；　even　with　instruments　which　have

been　devised　for　the　purpose。



_Fig。　90。　Course　of　a　Bomb。_



Instead；　therefore；　of　relying　on　the　barometer；

the　ship　is　equipped　with　a　telescope　which　may

be　instantly　set　at　an　angle　of　45　degrees；　or　vertically。



Thus；　Fig　91　shows　a　ship　A；　on　which　is

mounted　a　telescope　B；　at　an　angle　of　45　degrees。

The　observer　first　notes　the　object　along　the　line

of　45　degrees；　and　starts　the　time　of　this　observation

by　a　stop　watch。



The　telescope　is　then　turned　so　it　is　vertical；

as　at　C；　and　the　observer　watches　through　the

telescope　until　the　machine　passes　directly　over

the　object；　when　the　watch　is　stopped；　to　indicate

the　time　between　the　two　observations。



_Fig。　91。　Determining　Altitude　and　Speed。_



The　height　of　the　machine　along　the　line　D　is

thus　equal　to　the　line　E　from　B　to　C；　and　the　time

of　the　flight　from　B　to　a　being　thus　known；　as

well　as　the　height　of　the　machine；　the　observer

consults　specially…prepared　tables　which　show

just　what　kind　of　a　curve　the　bomb　will　make　at

that　height　and　speed。



All　that　is　necessary　now　is　to　set　the　sighter

of　the　telescope　at　the　angle　given　in　the　tables；

and　when　the　object　to　be　hit　appears　at　the　sight；

the　bomb　is　dropped。



THE　GREAT　EXTENT　OF　MODERN　BATTLE　LINES。

The　great　war　brought　into　the　field　such　stupendous

masses　of　men　that　the　battle　lines　have

extended　over　an　unbroken　front　of　over　200

miles。



In　the　battle　of　Waterloo；　about　140；000　men

were　engaged　on　both　sides；　and　the　battle　front

was　less　than　six　miles。　There　were；　thus　massed；

along　the　front；　over　20；000　men　every　mile　of

the　way；　or　10；000　on　each　side。



In　the　conflict　between　the　Allies　and　the　Germans

it　is　estimated　that　there　were　less　than

7500　along　each　mile。　It　was　predicted　in　the

earlier　stages　of　the　war　that　it　would　be　an　easy

matter　for　either　side　to　suddenly　mass　such　an

overwhelming　force　at　one　point　as　to　enable　the

attacking　party　to　go　through　the　opposing　force

like　a　wedge。



Such　tactics　were　often　employed　by　Napoleon

and　other　great　masters　of　war；　but　in　every　effort

where　it　has　been　attempted　in　the　present

conflict；　it　was　foiled。



The　opposing　force　was　ready　to　meet　the　attack

with　equal　or　superior　numbers。　The　eye

of　the　army；　the　aeroplane；　detected　the　movements

in　every　instance。



THE　AEROPLANE　DETECTING　THE　MOVEMENTS　OF

ARMIES。In　the　early　stages　of　the　war；　when

the　Germans　drove　the　left　of　the　French　army

towards　Paris；　the　world　expected　an　investment

of　that　city。　Suddenly；　and　for　no　apparent

reason；　the　German　right　was　forced　back　and

commenced　to　retreat。



It　was　not　known　until　weeks　afterwards　that

the　French　had　assembled　a　large　army　to　the

west　and　northwest　of　Paris；　ready　to　take　the

Germans　in　flank　the　moment　an　attempt　should

be　made　to　encircle　the　Paris　forts。



The　German　aviators；　flying　over　Paris；　discovered

the　hidden　army；　and　it　is　well　they　did

so；　for　it　is　certain　if　they　had　surrounded　the

outlying　forts；　it　would　have　been　an　easy　matter

for　the　concealed　forces　to　destroy　their　communications；

and　probably　have　forced　the　surrender

of　a　large　part　of　the　besiegers。



The　aeroplane　in　warfare；　therefore；　has　constantly

noted　every　disposition　of　troops；　located

the　positions　and　judged　the　destination　of　convoys；

the　battery　emplacements；　and　the　direction

in　which　large　forces　have　been　moved　from

one　part　of　the　line　to　the　other；　thus　keeping　the

commanders　so　well　informed　that　few　surprises

were　possible。



THE　EFFECTIVE　HEIGHT　FOR　SCOUTING。It　has

been　shown　that　aeroplane　scouting　is　not　effective

at　high　altitudes。　It　is　not　difficult　for　aviators

to　reach　and　maintain　altitudes　of　five　thousand

feet　and　over；　but　at　that　elevation　it　is　impossible

to　distinguish　anything　but　the　movement

of　large　forces。



SIZES　OF　OBJECTS　AT　GREAT　DISTANCES。At　a

distance　of　one　mile　an　automobile；　twenty　feet

in　length；　is　about　as　large　as　a　piece　of　pencil

one　inch　long；　viewed　at　a　distance　of　thirty…five

feet。　A　company　of　one　hundred　men；　which　in

marching　order；　say　four　abreast；　occupies　a　space

of　eight　by　one　hundred　feet；　looks　to　the　aviator

about　as　large　as　an　object　one　inch　in　length；　four

and　a　half　feet　from　the　eye。



The　march　of　such　a　body　of　men；　viewed　at

that　distance；　is　so　small　as　almost　to　be　imperceptible

to　the　eye　of　an　observer　at　rest。　How

much　more　difficult　it　is　to　distinguish　a　movement

if　the　observer　is　in　a　rapidly…moving　machine。



For　these　reasons　observations　must　be　made

at　altitudes　of　less　than　a　mile；　and　the　hazard

of　these　enterprises　is；　therefore；　very　great；

since　the　successful　scout　must　bring　himself

within　range　of　specially　designed　guns；　which

are　effective　at　a　range　of　3000　yards　or　more；

knowing　that　his　only　hope　of　safety　lies　in　the

chance　that　the　rapidly…moving　machine　will　avoid

the　rain　of　bullets　that　try　to　seek　him　out。



SOME　DARING　FEATS　IN　WAR。It　would　be　impossible

to　recount　the　many　remarkable　aerial

fights　which　have　taken　place　in　the　great　war。

Some　of　them　seem　to　be　unreal；　so　startling　are

the　tales　that　have　been　told。　We　may　well　imagine

the　bravery　that　will　nerve　men　to　fight

thousands　of　feet　above　the　earth。



One　of　the　most　thrilling　combats　took　place

between　a　Russian　aeroplane　and　a　Zeppelin；　over

Russian　Poland；　at　the　time　of　the　first　German

invasion。　The　Zeppelin　was　soaring　over　the

Russian　position；　at　an　altitude　of　about　a　mile。

A　Russian　aviator　ascended　and　after　circling

about；　so　as　to　gain　a　position　higher　than　the

airship；　darted　down；　and　crashed　into　the　great

gas　field。



The　aviator　knew　that　it　meant　death　to　him；

but　his　devotion　led　him　to　make　the　sacrifice。

The　Zeppelin；　broken　in　two；　and　robbed　of　its

gas；　slowly　moved　toward　the　earth；　then　gradually

increased　the　speed　of　its　descent；　as　the

aeroplane　clung　to　its　shattered　hulk；　and　by　the

time　it　neared　the　earth　its　velocity　was　great

enough　to　assure　the　destruction　of　all　on　board；

while　the　ship　itself　was　crushed　to　atoms。



One　of　the　most　spectacular　fights　of　the　war

occurred　outside　Paris；　when　one　of　the　German

Taubes　attempted　to　make　its　periodical　tour

of　observation。　One　of　the　French　aeroplanes；

which　had　the　advantage　of　greater　speed；

mounted　to　a　greater　altitude；　and　circled　about

the　Taube。



The　latter　with　its　machine　gun　made　a　furious

attack；　during　these　maneuvers；　but　the　French

ship　did　not　reply　until　it　was　at　such　an　elevation

that　it　could　deliver　the　attack　from　above。

Then　its　machine　gun　was　brought　into　play。　As

was　afterwards　discovered；　the　wings　and　body

of　the　Taube　were　completely　riddled；　and　it　was

a　marvel　how　it　was　possible　for　the　German　aviator

to　remain　afloat　as　long　as　he　did。



Soon　the　Taube　was　noticed　to　lurch　from　side

to　side；　and　then　dart　downwardly。　The　monoplane；

in　the　pursuit；　gradually　descended；　but　it

was　not　able　to　follow　the　destroyed　Taube　to　the

earth；　as　the　latter　finally　turned　over；　and　went

swirling　to　destruction。



The　observer；　as　well　as　the　aviator；　had　both

been　killed　by　the　fire　from　the　monoplane。



In　the　trenches　on　the　Marne；　to　the　northeast

of　Paris；　where　the　most　stubborn　conflict　raged

for　over　a　week；　the　air　was　never　clear　of　aeroplanes。

They　could　be　seen　in　all　directions；　and

almost　all　types　of　machines　were　represented。

The　principal　ones；　however；　were　monoplanes。



THE　GERMAN　TAUBE。The　German　Taube　is　a

monoplane；　its　main　supporting　surfaces；　as　well

as　the　tail　planes；　are　so　constructed　that　they

represent　a　bird。　Taube　means　dove。　It　would

have　been　more　appropriate　to　call　it　a　hawk。



On　the　other　hand；　the　French　monoplane；　of

which　the　Bleriot　is　the　best　known　example；　has

wings　with　well　rounded　extremities；　and　flaring

tail；　so　that　the　two　can　be　readily　distinguished。



On　one　occasion；　during　the　lull　in　the　battle；

two　of　the　Taubes　approa