The Saline County journal. [volume] (Salina, Kan.) 1871-1893, 1888-04-12
TIMING FLYING SHELLS.
How Uncle Sam Finds Out just
How They Go.
The Boulsngs ChronograPh. and HoW It
Es OPeratsd-What . Velocity q
TWsnty-One Hundred Fset Per
Minute Really Means.


"ArUund the world In twenty hOursr'
"YOu don't mean itn
81 do. That's Just what velOciiy Of LOO
feet per second means. and that is what this
gun will do for = second or two as sure as
guns are guns
SO spoke one Of my naval friends as he
pointed 20 a gun long and slender as tele-
scope. writes an Annapolis (Md-) CORE
sPondent 70 the New York World.
But how can you measure any velocity
as great as THAR
Easily enough" asserted the scientific
young sea-dog. Just wait until we get this
fellow into position. aud you shall see for
yourself how the thing is done"
Thus i came 10 pass that one morning, In
answer 70 a note from my friend, found
myself landed on the long rickety wharf OF
the naval proving ground at Annapolis. A
less war ake-lOOking place II would be hard
10 imagine Two unpretentiOus frame build
ings on a small hill. barn, bit Of swamp
and farm house; but the stars and stripes
floating from dag pole marked IL as Uncle
Sans private property. l dived into the
larger Of the two buildings. Through the
open door ! saw on my right large uncar-'
peted room from which my friend called TO
me % come in On the walls were cases
with guns, pistols and Odd-i0Oking instru-
ments. a desk. big table, Photographic
outfit and three massive wooden pedestals
on which stood instruments. each Of which
an officer was busiy engaged in adjusting.
These are B0ulenge chronOgraphs," said
nv friend. cdding: We are going 70 IRE
Just aS SOM - that schooner gets out "
range"
'Fire whai''i said !. for I saw nothing
except some small arms. The gun you
saw last week retortei be. and then some
body outside sung out: '-Stand hy!7
The soflcbyiy was Lieutenant. with q
big red fiag ia ono hand and binucular IA
the other.
Ready. A. .Roaiy. b. Ready. Cr'
called ogt the three Officers in rapid success
sion, when fash. rattle, down came the rods
OF the ch7oDngraPhs- Rang, wbizz-rush-
roar! and way oVt in the Chesapeake
could see the splash. smash VI the shot
miles away.
"A ,. l0S.~ said some one, and turning
saw the three oficcr- b'ndng over the
table, each carefully measuring steel rod
about twenty inches long. its whole length
nearly covered by a thin zinc cylinder B
,, llO.' &C ,. H." they announced in turn,
which was entered in big books. the rOds
were again measured and the entries
checked.
Now said my friend. 'let me present
you 70 my fellow workers aud explain this
mystery Look out there .-Out there"
some hundred yards away was a shed with
some six or eight guns Of various sizes and
shapes. all pointing towards heavy butt Of
earth one hundred yards from them. Be-
q -. -.
wooden frames, like big picture frames,
with wire laced back and forth across them,
while here and there ran telegraph wires
which finally entered the room in which We
were and connected with the chrOuographs.
Now" sand my friend. "here is the
whole thing in a nutshell These chrono-
graphs consist Of a couple Of electrO-mag-
nets and little spring knife. The upper
magnet holds the long, uncovered steel
rod; the second holds a short steel rod
The gun being fired, the shot cuts the wire
in the nearest frame, or screen, as It is tech
nically called, and so breaks the circuit Of
the upper electrO-magnet, allowing the long
rod TO fall When the shell reaches the sec
ond screen, the one furthest from the gun,
IL breaks the circuit Of the second electro
magnet, thus allowing the shot-rod 10 fall.
the trigger Of the spring knife The knife,
being released, flies forward and makes q
dent in the zinc on the long rod. and 50 we
can measure the distance the long rod has
fallen before the knife marks il, and as this
space bears a distinct ratio TO the time,
and as the time is exactly that taken by the
shot in passing over the known distance be-
tween the screens, we know the time and
hence the shells velocity per second
But does not the short rod occupy some
time in falling and docs not the knife take
some Little time in striking he rod - askedL
$50 It does. and the way We got round
that is this" Here he hung both rods TO
their magnets .'See this key. II l press
II break simultaneously the circuit Of both
magnets and release both rods nj one and
the sans time Thus" and pressing the
key, down fell the rods. .' Now sec this
marx on the zine. That Is the mark made
by the knife and Is called the 'disiunctOr
reading and its from this mark that we
measure the distance that the long rod
falls At any rate, that Is the result prac-
tically, we take the difference between the
disjunctOr reading and the reading given by
the shot. which gives the distance between
the two marks, aud. a. / said before, il We
know the disianrc body fails we know the
time il was IN falling aui, consequently, the
time taken By the shot in gong over the
known distance between the two screens.
We use the three chronOgraphs as checks
upon each other; they are all connected
with the same screens and should give the
same result. The mean Of the three is
taken as the actual velocity. Then, ton, II
We had only the Que it might fan 10 acI, ard
n shot would be wasted. and as this costs
FOR the eight-inch rifle ABOUT sixty dollars a
shot II is quite consideration. even 20
Uncle Saln. Now ! believe have told sou
al there is tOii"
"But that shell did not 20 through that
young mountain OF sar,h you srs pleased 10
cal a butt before it weat skipping along he
bay, did itt''
"Sn. theEun was SIGHTED so a. just %
clear tho burt. and the -..,t WAS fired with
a view Of iefcrm ni1g if- range There are '
a couple Of observers Stationed ont near BAY
Ridge who mark on 4 plane table tue line
through the first splash of the shot. The .
intersection OF this lire on a chart with the .
line observed here. gives the point where .
the shot struck. aud - we measure he dis 4
lance"