The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1869-10-31
Popular Science.


INFLUENCE OF FoREsTs.-Mr. Becquerel in
late report on the influence of forests on ele-
ments, ,says:-There is one action which all vege-
tation, of whatever character it be, exerts, aud
that is the protection of the soil on which 1t
grows from forcible removal by floods. The
roots traverse the earth in all directions, and
bind 1t together, while the branches break the
force of the rain as it falls AS soon as a hill
side is cleared of forests, the rivulet-beds are
scored deeper and deeper, and the soil is
gradually washed down, leaving the rocks bare
The roots of trees have, in addition, tendency
TO facilitate the percolation OF water to the sub
soil, and thus to prevent its accumulation on the
surface, and the consequent production of
swamps, such as have been formed in parts
OF France within historic times
There is another beneficial effect pro-
duced by trees, that Of impeding the motion of
the air, and thus aifording shelter from wind
This action is, of course, limited, depending on
the height of the trees and the direction OF
motion OF the wind. If this direction be hori-
zontal the shelter afforded is very considerable,
as it has been noticed in Provence that hedge
two metres in height shelters space twenty-five
metres in width from the effects OF the mis-
tral.. Lastly, trees have decided influence on
health, in protecting district from unwhoe-
some eXhaations. 1t is found along the edge
of the Pontiue marshes that the existence of a
belt of wood is sufficient to insure immunity
from malaria to the peasants who live behind it.
These, then, are the most obvious beneficial ef-
fects on climate of the presence of forests
in country. As regards the direct in
huence OF vegetation on the ,tempera-
ture and the climate generally, the
author gives the notes of some experiments
which he has made on growing trees, in order to
determine their temperature and that of the
surrounding air at different times of the day.
The results seem to show that trees behave as if
they were dead or inorganic bodies receiving
heat from external sources and radatng it to
surrounding objects. The heat developed in the
process of growth was found to be quite inap-
preciable by means of the instruments employed
while the cooling influence usually assigned to
foliage, owing to the constant evaporation going
on from its surface, was shown to be utterly un-
founded
NPoRIzATIoN ACCELERATED.-Who has
paid attention to any liquid boiling in a glass
vase has doubtless remarked that the bells of
steam issue from a small number of points, some
times, indeed, from single one. 1t is not on
account OF the temperature of these points being
higher than that of the other places that this
difference arises; i'll most cases, slight spot or
small projection may be observed, around which
the steam-bells are formed. NJ. Thomlinson,
basing himself upon this observation, regards a
liquid ut the boil as a solution having an excess
OF its own Vapor and he thought that its Vapor-
zation might be accelerated, exactly as crystal
lization in solution having an excess of saline
matter is precipitated, by introducing into it n
solid nucleus. Among the substances that may
be used for this end, coke and vegetable carbon
or charcoal are the most active, the expert
ments made by NJ. Thomlinson being calcu-
lated to encourage manufacturers to put one
steam boiler Thus in simply heating water in
an earthen vase, nine hundred and ninety-five
grains are evaporated in twenty minutes; but,
alter adding few pieces of coke, the quantity
eyaporated in the same time amounts to eleven
hundred and thirty grains. An experiment
made with charcoal was still more striking in
its results. In this case the quantity of water
yaporizcd was increased more than quarter by
the introduction of II few pieces of vegetable
charcoal into the liquid. These experiments
were made under ordinary atmospheric pressure,
and 1T Is probable they would give still better
results If they were placed under more conside-
rable pressure An indirect advantage may also
arise from the use of this system, which is cer-
tainly not without its importance, viz, that coke
or charcoal deposited in the boilers will eflica-
cously prevent the deposit of ncrustations in
this deposit occasions. Those facts, to which
NJ. Thomlinson draws attention, are susceptible
of numerous practical applications.
SUNLIGHT AHD GLASS. 1t is we'll
known fact that, even independently from
the effects of rain and wind, glass, even
OF good quality, is affected by sunlight
The late DR.. Faraday made some observations
concerning this subject, and found that violet
cOlored glass became deeper and more intensely
colored than it originally was, after having been
exposed to direct sunlight for eight months. Mr.
Grafield, of Boston, United States, who has
been for more than twenty years in the whole
sale glass-trade, and is at the same time a good
observer, has recently sent to the Photographic
Society of Marseiles a series of the results
of his researches and observations on
this subject, in which he comes to the concu-
sion (Which is especially important to photo
graphers) that glass is even sensibly affected
after one single days exposure to the suns rays,
and that all glass, without exception, including
that used for optical purposes, is more or less
| acted upon, even when made from the best ma
terials and by most experienced workmen;
| greensh glass seems to become the least
| affected. The author has sent to Marseilles
| a series of photographs representing the tinge
,A cha, It,nn IN intin nYNI
kinds Of glass after exposing them to sunlight.
| Cosmos.
| SOIL TEMPERATURE.-The temperature of the
soil is affected by first, the exposure of the sur
| faces second, the nature of the soil third, its
| permeability by rain and the presence of under
| ground springs; fourth, the suns declination;
| fifth, the elevation above the sea. and conse-
| qucntly the heating power of the suns rays;
! and, sixth, the amount of cloud and sunshine.