New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1895-08-26

| dlcular. and Its extremity the apex.
Pains first having been taken to fix the sight G
| at the angle which 1t forms with B so that this
important factor will not be altered the Siding
age is moved outward along until G points
at the distant object. There. then. is second
right-angled triangle, whose larger base Is accu-
ratey measured by the small register c. and
whose perpendicular is the total distance from the
standard of the instrument. This is what is to be
ascertained. II the angie which G forms with
X has been preserved with mathematical accuracy.
the perpendicular OF the greater triangle will be
many times larger than the perpendicular OF the
smaller one as the base Of the big one Is larger
than the base of the smaller one Suppose. then.
that in the first observation the operator had a
base one-fourth of inch long. and in tho second
base OF fifteen inches then. II he multiplied the
length OF A (Which will suppose to be two and "A
half feeO BY sixty he would have the distance re-
quired namely, 100 feet Obviously. If the object be
much than this. the base in the first OBJ
servaton should be larger. and should be set at
sharper angle with b; but If the object be further
away, then the angle would be larger.
In no case has Mr.. Kelum attempted to make any
measurements with a base OF less than quarter
of an inch for the small triangle; and in practice 1t
is doubtful whether this can be done with satsfac-
tory results For the larger TRANCE the inventor
claims that II is practicable 10 get larger base
than the ordinary length of the beam B twenty
four inches) by adding extra sections in such way
as to keep the beam perfectly rigid. OF course. If
the base were bent never so slightly II would spoil
the computation.
To ascertain the height Of object with MT
Kellums instrument. first finds out the distance
as already described. Next, \ having been pointed
directly the bottom edge OF the object the opera
tor sights along the upper edge OF that arm ana
sees where the top OF the object intersects the
gradated upright post -, the end of \. Then as
the length of A is TO the total distance so the
amount measured off on ID is to the total height
To get at the breadth the arm is directed to the
efthand edge of the distant object and the swing
ing arm + is moved along the brass arc r until IL
points to the right-hand edge The arc is gradu-
atcd not to show degrees OF circle but actual
distance along imaginary line at right angles
with the further end OF A. Hence the same meth
DDS are employed to compute width as distance and
height
Mr. Kelum says. for instance. that with his full-
sized model he measured the height of poplar
stump 600 feet and got seventy-two feet as MS
result Subsequently. the tree was cut down. and
tapene gave seveNty-one feet ten inches as the
length. on another occasion he measured a post
24O feet off and ascertained its height within half
an inch Of tapelne measurement He also meas
ured the length Of a church building nearly mile
off and got proportionately accurate results lie
believes that an Intelligent. careful operator can
use this instrument advantageousy for great deal