The Caledonian. [volume] (St. Johnsbury, Vt.) 1837-1867, 1845-10-11
FROM LardneT's Lectures.
KNOWLEDGE FOR THE PEOPLE.
T h C Dew

The phenomena Of dew is rendered celebrated Cor
the extremely beautiful investigation ont OF whhh the
discovery of its theory We are indebted 10 an
eminent natural philosopher, On. WELLS, 70. this
theory, and he developed ii complete in al ~ parts;
and am sure that you will consider il most hsauti-
tu and satisfactory If succeed 10 making il as
clear as ought to do. When any natural pheuo uena
IS to be examined, and clear cause assigned 70 1.-THE
first duty of the enquirer-though unfortunately Il is
one not always observed, is TO obtain clear oo,cep-
ton of the thing the effect itself which We pro-
pose to examine. In an inquiry into the nature and
origin ofdew, it is necessary frs Distinguish il
from other things which may be lsed to fesem.
bic ii more or less For instance, not rain. rair
falls in dropS, regularly formed in the air before thew
deposited on the carth's surface. Dew docs not:
nor is it known to exist in liquid state until Il
touches the body which it is deposited Rain Glls.
dew collects. Rain is driven upon the atder
side of leaf dew is likely to be found there az
elsewhere. Nor is dew the same as fog; Tor there
exists none unless there be dampness in the ntmos-
phere, while dew is never found unless the sky DO
clear and the air dry. You see, them that dew is as
distinguished from other objects. We Gnd !, eIs, ns
in objects uponlhe surface of the earth clear nell
lucid drop; but in order clearly to investigate hs
character. must open the Book OF Nature. AID
diligently read its pages. The nncients set Up LOFTY
theories, which they only thought of supporting; the
modern philosophy submits Nature to the severss. e
animation, and EFFORTS from her the truth. Vivian
any question is proposed for investigation the first and
most natural inquiry is, whether there be ans Other
similar effects FOR ic there are they are probably owl
ing to the cause; and ifthis be known. ia tie
latter case, il is in the former also
kova O,sa bc, H.
canter filled with cold water in warm day, be set
upon table its surface will soon be covered with d,
cloudy film, which soon forms itself into large peHu.
cid Drops which have all the characteristics OF dew
Of this appearance upon the docnner we perfect,
ly know the cause.-the watery particles which Away,
in warm weather are suspended in the air, are con-
densed by the GOODNESS of the and deposited up.
on the surface of the decanter where they como In
contact Now, said DR.. Wells, If the phenomena Of
dew SO closely resembles this which witness upon
the decnnter, why mny it not have the same cause
lie, hereupon endeavored to trace closely the ana.o
gy, between the two. He knew that moisture was
deposited upon the decanter because the deesntsr
was colder than the air around it, To bring
the beloved object into tho same prediea-
mcnl is incumbent show that this object is colder
than the surrounding air If this be proved, real
step VIII nave Deen Hiaue III the investigation. n
DR. Wells clearly saw and lie likewise saw the
sity of applying to nature for this proof lie took
two thermometers and plunged one among the leaves
of plants in the night time when the dew flllsi the
other he suspended in the atmosphere some i've o.
three feet above the leaves. lie watched these two
thermometers durius the night, and found that The
one among the leaves 20 degrees lower Ihas
the other. Here he had made one real step in thu
vestgation the analogy of dew and the drnps tho
decantor thus far was complete.
Now said Wells, we have got this importsH poiati
tho dew is deposited upon the plants bealuse ihoy
are colder than the surrounding air The az always
sustains quantity of yapor; and the plants, has'ag
los, their temperature operate just as did the ssesn-