Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1890-01-25

not as appreciate, Existing guns. in
the hands of gun captains Of fair skill.
will put about onefourth the shots fired
from them when ahoat into a target
twelve feet high and of most any length
the vertical rather than the horizontal
being the chief consideration-when at
2. 900 yards. range. the distance being
accurately known This will probably
be the effective range for opening future
engagements.
Such is at least the opinion held by
most gunnery experts both in this coun-
try and in foreign services. 1t is to over
come this element of uncertainty in the
calculation OF the distance the enemy is
off, and to thereby increase the range at
which,the gun reiSns supreme, that Lieut..
Fiske, United States navy, has brought
his knowledge and ingenuity to bear.
His range finder, which is illustrated by
the accompanying cut, introduces cleo
tricity and depends almost entirely upon
the principles of the Wheatstone bridge
or the electrical balance. The instru-
ment consists Of an iron tripod support
ing a fiat iron table, carrying a telescope
which has vertical and a horizontal mo
ton, and which is also in the circuit of an
electric current. In order to secure hav-
ing base line, no matter whether the
vessel presents bow, stern or broadside
to the target, there are four of these tri-
pods on each ship, one at either end Of
the bridge forming the shorter base line:
a third forward and fourth aft. form
ing a longer base line. which is about tho
length of the ship.
The two tripods forming the base lines
are connected with the electric battery,
carrying a weak current. two accumula-
tor cells being sufficient, and also with
a galvanoineter The principle involved
in finding the range and position of an
object depends upon the determination
of fractional portion of conducting
body bearing in length ratio to all angle
between two lines of sight directed upon
the distant object, and the measurement
of the electrical resi- stance of that length.
The practical working of the apparatus
includes three observers. one at each
telescope, and third at the galvanom-
eter. On topof one Of the tripods, and
underneath the telescope, is IA slider
which is adjustable and has its middle
portion insulated SO that the current cam
not pass across, but goes by wire to the
salvanometer. Moving this slider one
way or another increases or lessons the
resistance and causes detection in the
needle of the galyanometcr.
Ono IF tho ohroryarl ui.ybt- b;s t,1n
scope at the target, and certain deAec-
ton of the needle is observed. The other
observer also sights on the object, and
the needle shows a change in detection.
The slider is then moved until the needle
of the galvanometer reads zero, and the
position of the slider IN reference to a
fixed scale of yards shows at once the
distance the target is away from the OBJ
jet Well known principles of the re-
aton Of arcs and the sides and angles of
triangles bear to each other render it
possible, from the data Of lengths, angles,
etc. Of the apparatus itself to extend
their proportions to any distance, and it
is by THESE methods Of proportion and
the electric balance that the REQUIRED
distance is obtained. Its application is
not confined to vessels alone, as II can
be applied anywhere where a base line
Of known length can be obtained.
For instance, the telescopes. suitably
mounted, conld be sent ont on the Skin
m'sh line or to any other advanced DO
sition and the distance of an enemy's
works or troops accurately determined,
so that the g1nners would know at what
range to elevate their guns. The trouble
on shipboard has been that the base line
has heretofore proved too short for nrac-
teal use, and the delay has been caused
by time required for Communication be-
tween the two Observers