than the air, convey the heat of the atmosphere to the earth, and when
the temperature of the earth is higher than that of the air, they trans-
mit the heat in the opposite direction from the earth. It follows, then,
as conductors of heat, the forests play an important part towards the
equalization of the temperature of the earth and the atmosphere.

In temperate latitudes especially the effect of forests on temperature
is considerably increased by the nature of the foliage. A large propor-
tion of the trees are of deciduous foliage, and their radiating, as well as
their shading surface, is very much greater in summer than in winter.

The temperature of the forest in all climates is higher in winter and
lower in summer than that of the open ground. Every one who has
visited the forests with any frequency knows that he need go but a short
distance within its borders to escape the influence of even a furious
wind, and that woodmen engaged in felling trees in the winter rarely



100 FORESTS.

find inconvenience from cold winds, which penetrate but a short dis-
tance, even when the trees are devoid of their leaves. As the woods
shelter those within from the winds, they in like manner protect the
adjacent open country from the blasts which would otherwise sweep
over them, and which, by their cold and mechanical force, and by their
desiccating influence, prove very injurious to agriculture. Hence the
presence of a forest, in its effect on adjacent regions, is often equivalene
to a difference of several degrees in the latitude.

It has been remarked by Dr. F. L. Oswald that the " Prince de Ligne,
countryman and contemporary of Maria Theresa, wrote an essay ' On
the Location of the Earthly Paradise/ and after some reflection on the
hygrometric influence of different climates, calls attention to the fact
that ' paradise traditions, in locating the garden of Eden, differ only in
regard to longitude, but not to latitude. The latitude keeps always near the
snow -boundary , a line just south of the regions where snow may fall, but
will not stay on the ground. It passes through Thibet, Cashmere,
Northern Persia, and Asia Minor, and reaches the meridian of Europe
near the centre of the Mediterranean.' The nations that ' celebrated the
life as a festival ' have lived along this line, and we may doubt if in the
most favored regions of the New World human industry, with all the aids
of modern science, will ever re-unite the opportunities of happiness
which Nature once lavished on lands that now entail only misery on
their cultivators. All over Spain and Portugal, Southern Italy, Greece,
Turkey, Asia Minor, Persia and "Western Afghanistan, and throughout
Northern Africa, from Morocco to the valley of the Nile, the aridity of
the soil makes the struggle for existence so hard that, to the vast majority
of the inhabitants, life from a blessing has been converted into a
curse. . . . And all this change is due to the insane destruction of the
forests." 1

The effect of forests on the electrical state of the atmosjfliere, and the
generation of ozone, is also, doubtless, a force of great influence adding
to the general salubrity, and under some circumstances giving them
special potency.

While electricity results from any kind of chemical change or action,
of which there is much incessantly going on in the natural relations of
the forest to the atmosphere and soil, the condensation of vapor into
rain is, perhaps, the most prolific of all sources of electricity. And be-
sides this, which is apparent to all observers, when we consider the in-
visible, but none the less active processes of absorption and exhalation,
the amount of water daily absorbed from the soil by every thrifty tree,
and how small a proportion of this fluid consists of matter which enters
into new combinations and becomes a part of its solid frame-work, it is
evident that the superfluous water is somehow returned to the atmosphere

1 " Popular Science Monthly," vol. xi., p. 385.



FORESTS. 1 1 1 1

almost as rapidly as it is absorbed. Again when we reflect upon the
interposing obstacles to the dew. mists, fogs, and light showers and the
redispersing of the water from these sources into invisible vapor to cool
the air; and the influence of the same obstacles in heavy rains, serving
to break the big drops and scatter them into misty fragments — the mul-
tiplication and combination of these influences abundantly account for
the electrical state of the atmosphere of the forest.

Moreover, to the same active influences and electricity is due the
exalted activity of oxygen — the generation of ozone — always active, when
present, as a destroyer of organic matter in process of decay, and in this
case hastening the return of the emanations of vegetable decay to their
original elements — the elements of a pure and vivifying atmosphere.
Hence the specially invigorating effect of a forest atmosphere in some
states of the human system, and its general salubrity in all.

Sudden accession to the amount of vapor in the atmosphere, especially
if associated with a fall of temperature, are well known to have decided
effects on the state of the public health; and rheumatic and gouty in-
valids are proverbial for the certainty with which they foretell a storm
by their sensations — due to the decrease of atmospheric pressure.

According to some observations of Dr. Ballard, with reference to
seasons in England :

" Both in the colder and warmer seasons of the year, a comparatively
dry condition of the atmosphere is more dangerous to the public health
than a comparatively moist one." '

But these observations of Dr. Ballard seem to have been confined to
dense populations — to cities. How far they may be general, however, is

jested by the common salubrity of forests, notwithstanding their
dampness.

THE EUCALYPTUS.

Xo account of forests would be complete without an account of the
prophylactic properties of the eucalyptus. By it, especially, is illustrated
the functions of drainage, absorption, and distillation to a degree greatly
surpassing that of any other known plant.

The eucalyptus exists in great variety, and there is reasonable hope
that its climatological distribution may be greatly extended, although,
hitherto, its cultivation has met with but very limited success in climates
subject to frost. As just remarked, this tree exists in great variety, yet
observation has, until very recently, been chiefly limited to one species,
the E. globulus. There is good ground for belief that the anti-miasmatic
properties, with which this particular species is credited, are at least par-

1 " On the Influence of some of the more Important Elements of Weather upon
the absolute Amount of Sickness." British Medical Journal, June 12th, 1869.



102



FORESTS.



tially, if not indeed equally, possessed by several other species of the
same order.

The stem of the young plant is four-sided like the Mint family. The
leaves are heart-shaped and sessile. On each side of the square-shaped
stem is a depression within which the leaf is attached; the cordate notch
at the base of the leaf is so deep that the lobes of one leaf lie upon another,
appearing, at first sight, like the upper side of the perfoliate leaves of the
honeysuckle. Each pair is set at right angles with those above and




below, and with horizontal plane, the upper surface being exposed to
the sun and the under in the shade, and, as to plants generally, the under
surface only is supplied with stomata or breathing organs. They are of
bright, grassy-green color, thin, soft, and juicy. But ere the plants have
attained the age of ten years, a complete transformation of all the stem-
and leaf -characteristics sets in, and in the "grown-up" trees they have
wholly disappeared.

Instead of a square-sided, greenish, herbaceous-looking stem, we have
a huge white-colored trunk, and gnarled branches twisted into wild fan-
tastic shapes. The leaves are no longer amplexicaul, but stand well out
from the branch-stems, twisted upon and suspended by long petioles, and
instead of being heart-shaped and opposite, they are now scythe-shaped,
and the plane of their surfaces wholly changed— their edges turned to
the sun and earth— and, most remarkable of all, the stomata, instead of
being limited to one surface of the leaf, are now distributed over both
surfaces. The color, instead of grass green, has turned to a bluish-
green, and gives significance to the name of l ' blue " gum tree. And



for] - rs.



L03



now, too, instead of the thin, soft, and juicy leaf of the young plant, Ave
have a thick, leathery, and dry leaf, but doubly equipped in their power
of distilling moisture, both sides of the leaf work equally, and they are
o placed that the sun's rays in co-operation with them, penetrating be
twees their vertical surfaces, are scarcely intercepted in the exercise of
their fullest force on the surface of the moist ground where these bene-
ficent trees are most wont to flourish.




As seen with its shining white bark in Tasmania and Central Au-
stralia, with its white or light-red and dark shadows of curious foliage
trembling in the passing breeze, and towering to the height of from
three hundred to four hundred feet, it is not tmfrequently a beacon to
to the thirsty traveller, for it signifies his approach to water, or at least
to the bed of a river or lake. Indeed, it usually marks the water courses
so well that a distinguished explorer observes " that in travelling along
the Darling and the Lachlan, I could with ease trace the general course
of the river without approaching the banks until I wished to encamp." 1



1 F. V. Muller, " Transactions of the Royal Society of Victoria," part 1, vol.



104 FORESTS.

A nearly allied species, the amygdalina growing amidst the deep
ravines of Dandemony, in Victoria, is said to measure the enormous
height of 480 feet — even outstripping the great California pines — and
there is a great number of such trees growing in that region.

In great contrast, a dwarf species, called by the natives " goborro,"
grows only in places subject to inundation and in swamps, and usually
carries markings on its stems, showing the height to which the water has
risen. One traveller, Mr. Oxley, remarks that during his journey there
was always water to be found where these goborro trees grew ; and Sir
Thomas Mitchell states that " all permanent waters are invariably sur-
rounded by the " yarra" (the globulus, called "yarra" by the natives).
The one thrives on the margins of the stream, the lake and the lagoon,
and the other in the midst of the marshes and inundations, however long
their duration.

Still another species, the " clumosa," 'grows in sand too barren and
too loose for any other production, and but for this growth and prickly
grass the sand must have drifted so as to overwhelm the vegetation of
adjacent districts, against which nature appears to have curiously pro-
vided by the abundant distribution of these two plants, so singularly
adapted to such soil. The root of the "clumosa" resembles that of a
large tree ; but instead of a trunk, only a few branches rise above the
ground, forming an open kind of bush, often so low that a man on
horseback may look over it for miles. The heavy spreading roots, how-
ever, of this dwarf tree and the prickly grass together occupy the ground
and seem intended to bind down the sands of the vast interior of Au-
stralia. Their disproportioned roots also prevent the bushes from grow-
ing very close together; and the stems being leafless, except at the top,
this kind of eucalyptus is almost proof against the running fires of the
bush.

In all, more than twenty species of eucalyptus have been described,,
possessing a variety of useful properties and purposes.

The groves of the larger species, especially, are delightfully fragrant,
filling the air at great distances with the delicate aroma of balm or
lemon, and other odors indescribably delicious. All observers agree that
in Tasmania, and in those portions of Australia where the eucalypti
flourish, miasmatic fevers rarely or never exist.

Yet it seems to have taken the most enlightened nations about thirty
years after the coincidence of the existence of the eucalyptus growth
and the absence of malarial fevers in Van Diemen's Land was first de-
scribed to establish their relations.

The eucalyptus was first imported into France by Iff. Eamel, in 1856,
and for anything that appears to the contrary, solely at first as an orna-
mental tree. The first notable features of it were its extremely rapid
growth and powerful influence in drying up marshes, the dispersion of
mosquitoes and other insects which infest marshy places. In many



FOKE8T8. L05

places, in Algeria especially, it was rapidly brought into requisition for
i he redempl Iod of marshy lauds, and for the same purpose it was planted
in the valley of the Oshooni, a region of country celebrated alike Eo
Fertility and its insalubrity. And here it seems to have been first ob-
served, within the period of about ten years from the time the plants
were first introduced, that, together with the drying up of the marshes,
malarial fevers proportionally disappeared. It has since been introduced
at Cape Colony, into the French possessions in Africa, into various
places in the south of France, Cuba, and various other countries ; but in
none with decided results as in the famous Campagna of Rome, a place
no less famous for its deadly fevers in modern, than for the evidence of
its greatness in former times.

The following sketch of the Campagna, and history of the introduc-
tion and effects of the eucalyptus there, is by H. N. Draper, F.C.S.'

" One lovely morning in last October, we left our hotel hard by the
Pantheon, and in a few minutes came to the Tiber. If we except the
quaint and bright costumes of many classes of the people, and the ever
changing street-scenes of Rome, there is nothing in the drive of very
much interest until we reach the river. Here, looking back, we see the
noble structure which crowns the Capitoline Hill. The fine building on
the farther bank of the river is the Hospital of St. Michele. On this side
we are passing the small harbor of the steamboats which ply to Ostia.
Presently, the Marmorata, or landing place of the beautiful marble of
Carrara, is reached. From here a drive of a few minutes brings us to the
cypress-covered slope of the Protestant Cemetery, where, in the shadow
of the pyramid of Certius, lie the graves of Shelley and Keats. Apart
from the interest attached to these two lonely tombs, and the memories
aroused by their touching epitaphs, no Englishman can resist this secluded
spot, and look without deep feeling upon the last resting-places of his
countrymen, who have died so many miles from home and friends. The
cemetery is kept in order and neatness, and flowers grow upon nearly
all the graves.

" Our route next lay along the base of that remarkable enigma, the
Monte Testaccio, a hill as high as the London Monument or the Yen-
dome columns at Paris, made entirely of broken Roman pots and tiles,
as old perhaps as the time of Nero! Leaving behind this singular heap
of earthenware, we thread long avenues of locust trees, and presently,
passing through the gate of St. Paul, reach the magnificent basilica of
that name. Nor can I pause here to dwell upon the marvels of this
noble temple; or to tell of its glorious aisles and column-supported gal-
leries; of its lake-like marble floor, or of the wealth of malachite, of lapis
lazuli, of verae antique, of alabaster, and of gold, that has been lavished
upon the decoration of its shrine. I must stop, however, to note that

1 From a contribution to Chambers' Journal, for March 26th, 1881.



106 FORESTS.

nowhere lias the presence of the dread malaria made itself so obvious to
myself. We had scarcely entered the church when we became conscious
of an odor which recalled at once the retort-house of gas-works, the
bilge water on board ship, and the atmosphere of a dissecting room; and
we were obliged to make a hasty retreat. There could be little doubt
that the gaseous emanations that produced this intolerable odor were
equally present in the campagna outside, but that in the church they
were pent up and concentrated.

" Even did the space admit, this is not the place to enter into pro-
longed dissertation on the history or causes of this terrible scourge of the
Soman Campagna, the fever producing malaria. The name expresses
the unquestionable truth that it is a gaseous emanation from the soil;
and all that is certainly known about it may be summed up in a very few
lines. The vast undulating plain known as the Campagna was ages ago
overflowed by the sea, and owes its present aspect to volcanic agency.
Of this the whole soil affords ample evidence. Not only are lava, per-
perino, and the volcanic puzzuolana abundant, but in many places, as in
Bracciano and Baccano, are to be seen the remains of ancient craters.
When the Campagna was in the earliest phase of its history, it was one
fertile garden, interspersed with thriving towns and villages. It was also
the theatre of events which resulted in making Rome the mistress of the
world. This very supremacy was the final cause of its ruin and of its
present desolation. While the land remained in the possession of small
holders, every acre was assiduously tilled and drained; but when it passed
into the hands of large landed proprietors, who held it from the mere
lust of possession, it became uncared for and uncultivated. Filtering into
the soil loaded with easily decomposed sulphur compounds, the decom-
posing vegetable matter finds no exit through the underlying rock. The
consequences may be imagined, but to those who have not experienced
them, are not easily described. This once fertile land is now a horrid
waste, untouched, except at rare intervals, by the hand of the farmer,
and untenanted save by the herdsman. Even he, during the months of
summer when the malaria is at worst, is compelled, if he will avoid the
fever, to go with his flocks to the mountains. It may be mentioned, in
passing, that the malaria fever, or ' Roman fever/ as it has been called,
has been the subject of recent investigation by Professor Tommasi-Cru-
delli, of Rome, who attributes it to the presence of an organism, to which
the specific name of Bacillus malaria has been given.

" Leaving St. Paul, we pursued for a short time the Ostian road; and
at poor Osteria, where chestnuts, coarse bread, and wine, were the only
obtainable refreshments, our route turned to the left, along a road pow-
dered with the reddish dust of the pozzuolana — the mineral which forms
the basis of the original "Roman cement," large masses of which rock
form the road-side fences. After a drive of perhaps half an hour, we
found ourselves at the Monastery of Tre Fontane (three fountains). The



FOK I 1 7

•

Abbey of the Tre Fontane comprises within its precincts three churches,
<>!' which the earliest dates from the ninth century. One of these, San
Paolo alle Tre Tbntcme, gives its name to the monastery. A monk,
wearing the brown robe and sandals of the Trappist order, met us at the
gate. The contrast now presented between the sterile semi-volcanic
country around, and the smiling oasis which faces us, is striking. Here
are fields which have borne good grass; some sloping hills covered with
vines; and directly in the fore-ground almost a forest of eucalypt
trees.

"We have come to learn about the eucalyptus; and our guide takes
quite kindly to the role of informant. What follows is derived from
his viva voce teaching, from my own observations on the spot, and
from a very interesting pamphlet, printed at Home in 1879, and en-
titled 'Culture de l'Eucalyptus aux Trois Fontanes/ by M. Auguste
Vallee.

" Before the year 1868, the abbey was entirely deserted. It is true
that a haggard-looking monk was to be found there, who acted as cice-
rone to visitors to the churches; but even he was obliged to sleep each
night in Eome. The place obtained so evil reputation that it was locally
known as 'The Tomb.' There are now twenty-nine brothers attached
to the monastery, all of whom sleep there each night. This remarkable
result, though no doubt to a great extent due to the drainage and altera-
tion of the character of the soil by cultivation, is unquestionably mainly
owing to the planting of the eucalyptus. It would take long to tell of
the heroic perseverance of these monks; of the frequent discouragements;
of the labor intermixed by sickness; of the gaps made in the number by
the fatal malaria, and the undaunted courage in overcoming obstacles
which has culminated in the result now achieved. Let us pass to the
consideration of the actual means by which so happy a change in the
immediate surroundings has been brought about. At Tre Fontane are
cultivated at least eleven varieties of eucalyptus. Some of these, as
E. viminalis and E. botryoides, flourish best where the ground is natu-
rally humid; E. reHnifera and E. meriadora love best a dryer soil. The
variety globulus (blue gum tree) possesses a happy adaptability to nearly
any possible condition of growth. At the monastery, as in most elevated
parts of the Campagna, the soil is of a volcanic origin, and there is not
much even of that, often only eight and rarely more than sixteen inches
overlying the compact tufa. But with the aid of very simple machinery
the Trappists bore into the subsoil, blast it with dynamite, and find, in
the admixture of its debris with the arable earth, the most suitable soil
for the reception of the young plants.

" The seeds are sown in autumn in a mixture of ordinary garden
earth, the soil of the country, and a little thoroughly decomposed manure.
This is done in wooden boxes, which, with the object of keeping the
seeds damp, are lightly covered until germination has taken place. When



108 FORESTS.

the young plants have attained to about two inches, they are transferred
to very small flower-pots, where they remain until the time arrives for
their final transplantation. The best time for this operation is the spring,
because the seedlings have then quite eight months in which to gather
strength against the winter cold. One precaution taken in planting is
worth notice. Each plant is placed in holes of like depth and diameter.
In this way no individual rootlet is more favored than its fellow and, as
each absorbs its soil nutriment equally, the regularity of growth and final
form of the tree is assured. A space of three feet is left between each
seedling; but so rapid is the growth that in the following year it is found
necessary to uproot nearly one-half of the plants, which finally find
themselves distant from each other about five feet. From this time,
much care is required in weeding and particularly in sheltering from the
wind, for the stem of the eucalyptus is particularly fragile, and violent
storms sometimes rage in the Campagna. The other great enemy of the
tree is cold, and this offers an almost insurmountable obstacle to its
successful culture in Great Britain. It seems to be well proved that
most of the species will survive a winter in which the temperature does
not fall below 23 ° Fahr. How fortunate is the circumstance that the
culture of the tree at Eome, may be learned from the fact that the mean
lowest temperature registered at the observatory of the Roman College
during the years 18G3-*7-4 was 23.18 . Once only in those years a cold of
20° was registered, and even that does not seem to have injured the
plants; but when, in 1875, the minimum temperature fell to 16 J , the
result was a loss in a single night of nearly half the plantation of the
year.

" But when, as at Tre Fontane, the conditions of growth are on the
whole favorable, the rapidity of that growth approaches the marvellous.
The mean height, for example, of three trees, chosen for measurement by
M. Yallee in 1879, was twenty-six feet, and the mean circumference
twenty-eight inches. These trees had been planted in 1875, or in other
words were little more than four years old. Other trees of eight years'
growth were fifty feet high and nearly three feet in circumference at
their largest part. These figures refer to eucalyptus globulus, which
certainly grows faster than the other species; and it must be remembered
that in warmer climates the growth is even still more rapid. I have
seen, for example, trees of eucalyptus resinifera at Blidah, in Algeria,
which at only five years old were already quite sixty feet high.