The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1905-11-02

put under several different heads 10
W.T.: changes in temperature. in baro-
metro pressure, percentage of mois-
ture; wind and mira e: changes of
light: and personal equation
temperature: While a rise in tenn
perature of Z IL degrees will cause
the ball TO rise ten inches in 1000 wards.
the difference in the rise and fall of
temperature in these islands is so
small that While it should be taken
INTO account for the purpose of judg-
ing an conditions surrounding the
firing of a shot but little or no al
lowance VIII have to he made for il
here; still ii should not be lost sight
of by one seeking to qualify himself
TO become an expert
Barometric Pressure. So. TOO with
the barometer, a rise of a half an inch
VIII lower shot ten inches at 1000
yards put the probable change in the
reading of barometer during the
hrlng of score will seldom be suffi-
Gent TO justify changing the sights.
Percenta ge of Moisture: The amount
OF moisture in the atmosphere. rapidly
changing as IL does in this climate
mas probably more influence on eleva-
lions than perhaps any other cause
w hen it is considered that seven and
one-haf per cent of moisture will
cause ball to rise ten inches in 1000
yards it will be readily seen that with
our frequent showers the moisture in
the atmosphere changes so very rapid
iy that this element should be care
fully watched. So too if water gets
into the barrel and on the bullet the
amount of friction is reduced and ele-
walton raised and judging the result of
the shot Is then more a matter of
guesswork than anything else.
Wind and Mirage: DR.. Hudson in
writing OF the match for the Palma
Trophy in which the Canadians de-
feated the Americans at Ottawa, Sep
TENDER ID, 1901, says: Weather con-
dltIons We're good in the
morning and we profited by that fact
to the extent of gaining a lead of
twenty-five points over the English
team at 500 yards But in the after
noon, when the 900 yards stage was
about one-third completed very bad
weather conditions arose, with rapid
changes of light caused by clouds scud-
ding by; the wind came in fierce gusts
veered continually from one point to
another. and small but strong eddy
currents formed on the range. Under
these conditions with nearly every flag
pointing a different direction, the only
reliable way of gauging the wind was
by observing the mirage through
telescope trained on the target This
the English team had found in three
weeks practice to be the only relia-
BILE way of gauging the wind on that
range, while we We're almost totally
unfamiliar with the method and had
not even brought a suitable telescope
with US. The result was that the En-
glishmen overcame our lead and gain
ed twelve points on us
Since that match mirage has always
been a very strong factor in judging
the extent of the lateral detection of
the ball The speed at which the
bubbles travel across the glass and
the amount of mirage must be taken
into account in determining the speed
of the wind. and also the fact that
apparently the target to some extent
is displaced Gts image seeming to be
carried along with the wind) which
calls for an additional allowance as
the mirage increases. A head wind
carries the mirage down and a rear
wind UP and as the mirage increases
or decreases allowance must be made
in the elevations in addition to that
made for the velocity of the wind
Most marksmen pay a great deal of
attention to the DETECTION of the ball
to the right or left as influenced by
the wind, but apparently pay little or
no attention to the retarding or ac-
celebrating influence. With such winds
to contend against 1 think too often
the rise or fall of the ball was due
more to his having taken a finer or
coarser sight than usual and not give
due weight to the influence of the wind.
As is stated in the small arms firing
regulations: In considering the ac-
ton of the wind upon the flight of the
projectile the rifieman is at once met
with a tWo-fOid problem. He must de-
termine the probable effect upon ele
Vations and upon reflections or deVia-
tions. To arrive at any satisfactory
conclusion it is necessary to consider
the wind force resolved into two COM
ponent forces, one acting in the plane
of fire, the other at right angles to
it. 1t is then possible to make the re-
quired allowances, essentially as if two
independent forces were acting, each
having a constant uniform direction,
but a variable strength
On the 1901 sight each point OF wind
gives six inches correction at the tar
get for every 100 yards of range, and
LII. IluuSOlt III NOi hluS OuL the liiIOufit
of DETECTION from Ordnance Depart
ment data has constructed table
which shows that for all ranges the
amount of DETECTION is approximately
twice as great for a PAS or 10 o'clock
wind as for a 1-5-7 or IL o'clock wind,
and that for a or o'clock wind it IS
two and a half times as great as for
a 1-5-7 or II o'clock wind. That four
mile wind blowing from 1 o'clock will
defect ball at 200 yards two inches,
blowing from 2 o'clock four inches,
blowing from three O'Clock five inches.
His table shows that four mile wind
at 200 yards viii defect a ball inches;
at 500 yards inches; at 600 yards IL
inches; at 500 yards 10 inches; at 800
yards % inches: at 1000 yards 20 inches,
and that the number of inches of de-
Election increases proportionately with
the strength of the wind.
Light: 1t. Casey says that the ques-
ton of light is largely a question Of