Delaware gazette and state journal. (Wilmington, Del.) 1883-1902, 1890-08-14
humidity AVID HRAr.
Some Interesting Facts Upon These
Much discussed subjects.


Much discussed SUBJECTS
From the New York Herald, July IS.
The heavy and sadden dOwnpour Of
rain here last evening" enjoying the air
OF the aqueous vapoP Which few hours
before caused so muoh sWeItering and
suffering of man and beast, brings the
question of tine physiological effect Of
humidity more to the front than that of
the morbifio effect OF great hsAt. The
Temperature yesterday was not extremely
high; bnt the suitr;neas, or, technically
speaking, the absolute humidity OF the
air, msde people feel that they were
thickly blanketed.
1t is very strange, af or all that has
besn printed in tile books about humidity
some who are supposed to be weather
wise speak of it as il 1t had marked
effect on humanity. a New York paper
solemnly tells Its readers that il the per-
oentage Of humidity on certain hot day
had remeined several har-S at 80, "the
suffering would have besA terrible and
the death. rate would have been much
increase This and similar remarks
about humidity Cor relative humidity, as
IL is tegs ,niealiy called), SO frequently
met with in some newspapers, show that
the subj tct is radically misunderstood.
1t maEes little difference in our suffer-
ings from intense heat whether the
humidity or relative humidity is SO OF so
per cent. In fact, 1t often happens when
the relative humidity in ''hot wAven
rises 20 90 or 95 that relief from the cp-
pressiv0 heat is imminent, for the rise in
dioateB the welcome approach Of cooler
current, cnusiDE condemnation of vRpor,
and consequently promises refreshing
showers.
Relative humidity is merely an express
sion of the percentage of the quantity of
vapor necessary to saturata the air, or of
Its degree Of dampnesB. When the rela-
tive humidity is 100 the air ID entirely
sGturated-i. D., it will hold no more
watsry vRpor unless its temperature is
raised, and il lis temperature is lowered
it's yRpor will be condensed. AS respects
the power Of man to endure atmospheric
heat, it makes no difference whether the
relative humidity is 10, as It sometimes
10 in India and Arabia, or 100. The only
difference in these cases is that in the
former rain is contra-indicated, while in
the latter failing weather" is at hand.
There may be actually very much more
watery vapor in the sir when the relative
humidity is so than when it is 100.
But observations Of the absolute hu-
nudity Of the cir are OF vast moment,
both for the purposes OF metsorology
and medicine. For by this term is meant
tie amount CT aqueous yapor present in
the Air-usually and most intsllieibly ex-
presses by the number of grains of vapOr
per cubic foot of ais. The capacity of
air for storing vspof varies directly with
its temperature. Thus during midwinter
do nfa nj
grain OF water to the cubic foot, while
the air of Key West contains six grains,
and in July the latter averages over nine
grains, and sometimes in cYclonic weather
twice as many. Still greater contrasts in
the absolute humidity of continental or
mountainous and li,toral or insular
regions might be mentioned.
II an Invalid desires to get out Of q
damp climate he must Of course 90 where
the average relative humidity is low
that is, where the skies are not always
ready to weep In england when the
Thermometer registers 40 the weather is
usually very damp. But il the game air,
She dampneTs OF which in England would
greatly distress rheumatic or consump-
tive, should be transferred to an equa-
torial country it would be exceedingly
dry, though in both countries it con
tanned The same number of grains Of
water vapor per cubic foot.
But when we refer to the dangerous
effects Of our "hot wsves" on the public
health, it is evident thst the point Of
gfestest importance is not at all the rela-
tive humidity Of the air, but the actual
amount Of vapor Suspended In it. Had
we been under i maximum temperature
OF 1902 Fahrenheit in the interior OF
Algeria or in Colorado, where the air oon-
sstns but very littls water, we should not
have felt half rs much oppressed and
Hiekened by the heat as in the vRpor-
lGdon air OF the Atlantic seabosrd.
1t IS, therefore, all important in san.
iary view thHt observations of the actual
humidity should be irsugursted, RB fur
niahing the only scientific basis for pre-
dieting the severity and morbific effects
OF any passing shot waye1 or its infu-
enoe in raising the death.rste from sun
strokes, prostTatione and cholerRio and
ether summer disorders. Moreover, 90
the actual amount Of yapor secreted in
the sir determines the radiation Of heat
from tina soil, no scientific basis for the
prediction Of the thermometric range
itself can be until such observations are
systematically made and published.