Telegram-herald., 1890-01-31

p
the hands OF gun captains of fair skill,
VIII put about one-fourth 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
1900 yards range, the distance being
accurately known. This viii 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 Ia foreign services. II Is 20 over
come this element of uncertainty in the
calculation of the distance the enemy Is
of. and to thereby increase the range at
whschthe gun reigns supreme, that Lieut..
Fiske, United States navy. has brought
his know ledge and ingenuity 10 bear
His range finder. which Is illustrated bv
the accompanying cut, introduces cleo
tricity and depends almost entirely upon
the principles OF the Wheatstone bridge
or the electrical balance The insrru-
ment consists OF an iron tripod support
inC a fat iron table, CARRYING a telesCope
which has a vertical and a horizontal mo
ton. and which Is also in the circuit of an
electric current In order to secure hav-
ing a base line. no matter whether the
vessel presents bow, stern or brOadside
ts 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 a fourth aft, form
ing a longer base line, which is about the
length OF the ship.
The two tripods forming the base lines
are connected with the electric battery.
carrying a weak current, two acC1mula-
tor cells being sufficient. and also with
n galvanoneter. The principle involved
IN finding the range and position of an
object depends upon the determination
Of a fractional portion Of a conducting
body bearing IN length a ratio TO an angle
between two lines of sight directed upon
the distant object, and the measure ent
Of the electrical resistance of that length.
The practical working Of the apparatus
includes three Observers, one at each
telescope. and y third II the galvanom-
eter. ON tOpo Of one of the tripods and
underneath the telescope, Is a slider
which = adjustable and has its middle
/ portion insulated so that the current can
| not pass across. but goes by wire to the
galvauometer. Moving this slider one
wav or another increases or lessons the
resistance and causes % detection in the
needle az the EaIvanometer
One Of the Observers sights his tele-
/ scope az the target. and a certain deAec-
/ ton of the needle is observed. The other
7 observer also sights on the object. and
+ the needle shows change in detection.
+ The slderis then moved until the needle
7 of the EaIrauometer reads zero. and the
I position ot the slider SD reference 70 4
i 6xed scale ~ Yards shows as once the
I distance t0e target is away from the OBJ
/ ject WeU known principles of the re-
iation of arcs and the sides and angles Of
/ triarrIes hear o. each other render 10
I possible. FROM the data of lengths. angles.
-tc of the apparatus itself g. extend
/ their proportions 70 any distance. and It
/ Is rv these methods of proportion and
I rhe electric balance that the required
( distance Is obtained Irs application Is
I not confined c. vessels alone. IS it can
+ he applied anywhere whore base Line
7 known r-th can be obtained
For Instance. fhe telescope suitably
+ mounted -ould oe sent out on tha skir-
m -h hna % fo any other advanced Vo-
sincn ar1 rra distance n au ereuv's
works rr troops accurately 17rrrniraL.
so that tfa -1rre~s world know AZ w bas
I range So rste -ner E-s The trouble
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