The Helena independent. [volume] (Helena, Mont.) 1875-1943, 1890-05-02
LAWS OF CHANCE.
Evolution and Interesting Application Of
the Doctrine of Probability.

Evolution and Interesting Application OF
the Doctrine of Probability.
Some days ago Prof. T. G. Mendenhall,
of the geographical survey, lectured at the
National museum in Washington on
"Chance and the Long Rum In the be-
ginning of the lecture, says the Washing
ton Star, Prof. Mendenhall referred briefly
to the history of the doctrine of chance OF
the law of probability, saying that it had
its real origin in the work of Pascal. who,
about the year 1884, was called upon to Set
tie dispute between two gamblers. From
the time of Pascal to the present the sub
iect had received the consideration of the
ablest mathematicians, including especial
ly the great Laplace, and nearly every other
great mathematical scholar had contributed
10 its growth.
Then he proceeded to show that the
probability, or chance, or facility OF an
by means of fraction. When the value
of this fraction was one the event was Ger
tain to happen. References were made, in
ILLUSTRATION, to the tossing of coins, throw
ing dice, drawing balls from jars, etc. 1t
lis possible to calculate the probability of
some very complex events, and the pro.
mathematical methods. It was therefore
desirable to verify the result of this mathe-
NAUTICAL treatment of the subject by means
Df experiment. Several experimental tests
Df the principles of the doctrine of chance
were described. It was possible to calcu-
late the probability that q short stick in
ines would or would not lie across one of
those lines. Having computed this pr0ba-
bility. Prof. Mendenhall said that he had
verified the result by pitching stick upon
sdch surface and noting how it fell 10000
hines. This is probably the most expert
mental test ever applied.
The numerous applications of the laws of
chance were next referred to. Especial at
tention was given to its use in expressing
he credibility of human testimony and de-
termining its weight. If the credibility of
man were expressed by the fraction four
ifths it meant that what he said would in
The long run be true four times out of five.
Reasons were given for believing that the
average credibility was about three-fourths,
IN which was included not only any ten
lency to lie which might exist, but also
The chances of being mistaken. It was
we're one-half one witness was as good as
90: if il were less than one-hah the fewer
such witnesses called the better, and If
more than one-half additional testimony
would strengthen the evidence.
Some of the fallacies of gamblers were
0A0IJ0u VI, dnu A11UouAoGAOAAo wSAO hAsSAA w
show their absurdity. 1t was shown that
games of chance INDUCED in for gain were
pad from q business standpoint" If from
ho other, and in any case the loss was great
pr than the gain.
An application of tho laws of ''chance
and the long rum was made in proposed
plan for detecting authorship by sort OF
word analysis. The method depends on
twO or three assumptions.
The nature of the process, the speaker
laid, is extremely simple, but it may be use
nj to point out its similarity to we'll
Known method of material analysis, the
consideration of which actually first sug-
Eested to the writer's its literary analogue.
By the use of the spectroscope a beam of
neutrality-suspicious. light is analysed and its
tomponents assorted according to their
.ave length. As is well known. each ele-
nent. when intensely heated under proper
conditions, sends forth light which,
hpon prysmatic analysis. is found to
consist of groups of waves of definite
ength and appearing in certain definite
proportions. So certain and uniform are
he results Of this analysis that the appear
NICE of particular spectrum is indisputa-
Die evidence of the presence of the element
% which it belongs.
In q manner very similar it is proposed ia
lnalyze a composition by forming what
nav be called word spectrum or tchar-
kcteristic curve" which shall be oraphic
representation Of an arrangement Of
Eords according to their length and
o he relative frequency Of their %