Box 10, Folder 4: Correspondence 1867

[1867]

From a pamphlet recently published by Dr. Ferdinand Mueller, Director of the State garden at Melbourne, Australia, we learn that in that country there are 950 trees of 30 feet or more in height; among them, the Eucalyptus Amygdalina, reaching the height of 480 feet! thus overtopping the big trees of California. Many of these trees are found to be of very rapid growth, exceeding in this respect the trees of any other country.

"This marvelous quickness of growth combined with a perfect fitness for resisting drought, has rendered many Australian trees famed abroad, especially so in countries where the supply of fuel or of hard woods is not so readily attainable, or where for raising shelter an early and copious command of tall vegetation is of imperative importance. In Australian vegetation we probably possess the means of obliterating the rainless zones of the globe; for in the economy of nature, the trees, beyond affording shade & shelter, and retaining humidity to the soil, serves other great purposes. How much lasting good could be effected then, by the mere scattering

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of seeds of our own drought-resisting trees, at the termination of the hot season along any water course or even along the crevices of rocks, or over bare sands or hard clays, after refreshing showers. Even the rugged escarpments of the desolate ranges of Tunis, Algiers, and Morocco, might be wooded; even the Sahara itself, if it could not be conquered and rendered habitable, might have the extend of its oases vastly augmented; fertility might be secured again to the Holy Land, rain to the [Asiatic?] plateau or the desert of Atacama, or timber and fuel be furnished to Natal and La Plata. An experiment instituted on a bare ridge near our metropolis demonstrates what can be done."

"Judicious forest culture appropriate to each zone will vastly ameliorate the clime, and provide for the dense location of our race."

Ferdinand Mueller p. 18

3. A knowledge of the principles governing the atmospheric vapor is important to the architect and builder. I have a neighbor whose house is so constituted for lack of this knowledge that the walls act like the tumbler in taking the dew point, and is constantly covered by a deposit of moisture that renders the house almost uninhabitable. Curtains become wet and mouldy; the wall paper peels off; metallic [metallic] implements become oxidized [oxidized]; the inmates take colds; fires are needed at mid-summer to keep the rooms sufficiently dry for use. The result is that tenants avoid the house and it stands idle; taxes must be paid but no rents are received. A little practical application of the knowledge we have of the nature of atmospheric vapor and the effect of change of temperature upon it would have saved all this.

But it is not so much the exact amount of moisture or vapor in the air that concerns us as the relative proportion as compared with the full amount which the air could contain at the given temperature. Thus the absolute quantity may be so much as to exert a measure or elastic force of half an inch of mercury, and if the temperature of the air is 70º it will be necessary [to?] cool the air before moisture will be deposited on surrounding objects; but if the temperature is 65º it will require only a reduction of 6º——

EVAPORATION AND RAIN. — The yearly amount of evaporation, at any place is a very important element in its meteorological characteristics, and one but seldom ascertained by direct observation. Exposing a basin of water in the open air, will give an approximate result, and may be measured very accurately by means of a micrometer screw, turned down every morning until its point touches the surface. The following table shows the mean monthly result of observations so made at Milwaukee for over five years. Ice prevented observations from December to March, and for these months I interpolate what must have been about the amount, judging from the curve yielded by the others. A column is added showing the average amount of rain and melted snow during the same time.

The following table shows the amount of rain and melted snow for 1866, and also the mean quantity for 23 years: