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vestigators in Europe, in determining by instrumental observations, made at comparative stations in the open fields and in the forests, the influence of the latter upon the atmosphere in their vicinity, and upon the climate of the country generally.
That forests tend to render the climate of a country colder and more humid, has been known from general observation for many centuries; and the climate of Gaul, as described by Julius Cæsar, compared with that of France at the present day, has been osten cited as an instance of this fact. Yet it is only within a very recent period that anything like a full and systematic comparison has been attempted by instrumental observations.7
In selecting the location of these stations, one set of instruments is placed in the open fields, and the other in the woods, the former being as much as possible free from the influence of the forest, and the latter fully under its protection. Care is taken that the soil, altitude and other circumstances, except the forest-shade, are alike.
Their outfit generally consists of open-air thermometers psychrometers -- rain and snow gauges, barometers, wind-vanes, and instruments for observing the evaporation from surfaces variously covered as compared with a free water surface - the percolation of water through various soils, ozone records, and observations upon the periodical phenomena of animal and vegetable life generally, so far as influenced by the seasons.
In some cases the temperature of the interior of trees is recorded, and in some of the later systems of observation, it has been proposed to ascertain the temperature and humidity not only at the level of the tree-tops, but at a considerable height above them, the latter being obtained by the aid of masts, and by captive balloons that admit of the elevation of instruments.
Without going into details of the results of these observations, we may here remark, that records more or less complete in their plan have been established as follows :
In Saxony, since 1862-3, 'under the direction of Professor Krutzsch, of Tharand, at nine stations, embracing records of temperature, humidity, rain, snow, etc.
In Bavaria, since 1868, seven stations have been established
"An account of investigations in this line down to 1872 was published in that year by the Baron von Löfelboltz-Colberg, under the title of “ Die Bedeutung und IFichtig. keit des Waldes."
under Dr. Ernst Ebermayer, who in 1873 published very fully the results of four years' records, and in 1876 another work upon the formation of soil from the litter of woodlands, and the chemical statics of forest culture.9 It was his intention at the end of ten years to publish the results of that period in more extended form, but his recent removal from Aschaffenburg to Munich has apparently postponed, if it has not disappointed, this expectation.
In Prussia, a system of observations, nearly similar to those in Bavaria, was begun in 1874 under Professor A. Müttrich, of Eberswalde, and now includes fourteen stations in Prussia, Brunswick and Alsace-Lorraine. The results are published monthly 10 and annually, l1 and a careful study of so much as relates to the temperature of the soil has recently appeared. 12
In France, observations upon the rainfall in the woods and open fields were made under the direction of Marshal Vaillant, in 1866, near Paris, and published in the Atlas Meteorologique of the Imperial Observatory of Paris for 1867. In the same year, observations of more extended character were commenced at two forest stations and one agricultural station in the vicinity of Naney, near the eastern border of France, by Professor A. Mathieu of the school of Forestry at Nancy, and have since been continued. A summary of eleven years' observations was published in 1878.13
l'pon a general suggestion of the Congress of Agriculturists and Foresters at Vienna, in 1873, M. Fautrat, a sub-inspector in the French Forest Service, with the approval and aid of the Department, established two stations for comparative observations, one in the deciduous forest of Halatte near Fleurines, and the other in a forest of the Pinus sylvestris, near the village of Thiers. The former began in February 1874, and was continued four years ; the latter began in June 1875, and was continued three years. The results have been published by the French Forest Administration. 14
* Die physikalischen Einwirkungen des Waldes auf Luft und Boden, und seine klimatologische und hygienische Bedeutung, 1 Vol., 8vo, pp. 266 and 251 (with an atlas). Berlin, 1873.
* Die gesammte Lehre den Waldstreu, mit Rücksicht auf die chemische Statik des Waldbaues, I Vol., 8vo, pp. 300 and 116. Berlin, 1876.
19 Beobachtungs Ergebnisse der im Königreich Preussen, im Jlerzogthum Braunschweiz und in den Reichelanden eingericheteten forstlich-meteorologischen Stationen, 1 bis 5 Jahrgang. 1975–1879.
11 Jahresbericht über die Beobachtungs-Ergebnisse der im Königreich Preussen und in den Reichslanden eingerichteten forstlich-meteorologischen Stationen. 1 bis 4 Jahrgang. l-1873.
12 Beobachtungen der Erdbodentemperatur auf den forstlich-meteorologischen Stationen, in Prenssen, Braunschweig und Elsass-Lothringen. Von A. Müttrich. Sep. arat. Abdruck, aus der Festschrift zur 50 jahrigen Jubelfeier der Forstakademie, Eberswalile. 4to. pp. 33. Berlin, 1880.
13 Météorologie Comparée, Agricole et Forestière, 4to, Paris, pp. 70. Published by the Forest Administration, in connection with the Paris Exposition of 1878.
In Switzerland, observations were established in 1868 at three stations, by the Forest Administration of the Canton of Bern, and the results have since been published monthly in detail. 15 Onc of these stations is in a forest of beech, another of fir, and another of larch. The observations upon periodical phenomena, made at numerous stations in the Canton of Bern, under the same auspices, are published annually.16
In Austria, a plan of observations in Forest Meteorology has been prepared by Dr. Jos. R. Lorenz, and adopted as a part of the experimental system of researches under the general direction of Baron von Seckendorff, and under the authority of the Ministry of Agriculture. The plan is very comprehensive and includes some features not found in other systems.
In Sweden, two scientific stations have been established by the government, one at Upland in the southeastern part, and the other at Skaarsborg. They have been in existence some three or four years, but we have not met with any publication of the results.
In Italy, similar observations are being made at one or two stations under the direction of Dr. di Beranger, Director of the School of Forestry at Vallombrosa.
In Bohemia, a system of meteorological observations has been recently established under the auspices of the Bohemian Forest Society; and mainly in the interests of Forestry, which is very comprehensive in its plan, embracing a wide range as to elevation and exposure. So far as published, these records relate to the rainfall only, the observations being made by employés of the Forest Administration of the country.
The number of stations at the beginning in January, 1879, was 570, and at the end of the first year, it had increased to 689. In February of the present year, the number was 712. The results are published monthly in detail, 17 but as yet without attempt at generalization beyond the monthly means and totals. The system is under the care of Dr. Emanuel von Purkynê, a professor in the Forest academy of Weisswasser, and cannot fail of proving valuable to the country and to the world, by making us better acquainted with the laws that govern the rainfall in a wooded country, and the circumstances that determine the amount.
11 Observations Météorologiques. Faites de 1874, á 1878, par M. Fautrat. 4to, pp. 4 (with eight pages of plates).
15 Beobachtungs-Ergebnisse der im Kanton Bern zu forstlichen Zwecken errich. eteten meteorologischen Stationen.
16 Klimatologische und Phänologische Beobachtungen (Observations climatologiques et Phénologiques) im Canton Bern, 4to.
Special investigations concerning the temperature of the earth at different depths below the surface, and under various conditions, have been made in Russia and elsewhere. Thiese have more or less relation to forest-meteorology; and in several of the esperimental stations now in operation, the results will contribute to a further knowledge of this important subject.
We regret that hitherto so little has been done in our own country for the determination of the relations between the forests and the climate by direct comparative observations. With the exception of a few desultory records of temperature and rainfall, we are not aware that anything has yet been attempted for this object, at any institution, or by any observer in America. The greater general dryness of our atmosphere, and differences in our prevailing winds, appear to render the application of any general laws derived from European records very unreliable with us, and we never can have a certain knowledge of these laws as they operate in our country, until they shall have been determined from observations of our own.
The International Statistical Congress held at Budapest in September, 1876, the Meteorological Congress at Rome in 1877, and various conventions held by Agriculturists and Foresters in recent years, have had under discussion questions relating to the agricultural and industrial interests dependent upon climatic changes, and the extent to which these are modified by the woodlands of a country, and it is to be hoped, that effectual coöperation in these researches will ere long be rendered by American investigators.
Among the recent researches concerning the influence of forests upon the amount of water in wells, rivers and streams, and inci
17 Ombrometrische Beobachtungen der vom Böhmischen Forstvereine in den Forsten Bohmens in verschiedenen Sechöhen und Expositionen errichteten Stationen. Herausgaben von der Forstlehranstalt Weisswasser. Zusammengestellt und redigiert von Dr. Emanel von Purkyně, Professor an der Forstiehranstalt Weisswasser. Prague, 4to (in monthly parts).
dentally the effect of woodlands in maintaining the amount, we may notice as particularly worthy of attention, the publications of Counsellor Gustavus Wex,18 overseer of the works of improvement in the Danube, at Vienna. These memoirs are not only of interest from the facts that they embody, but also for their citations to other works, making them in some degree, a bibliography of the subject. They have been referred to commissions appointed by various academies of science, and the conclusions that they present have been approved by the highest authorities. They in fact confirm, by numerical statements, the observations of every one who has had an opportunity to notice the amount of water flowing in streams before and after the clearing of the district in which they rise, and through which they run. This amount affects the interests concerned in the hydraulic power of the larger streams, the supply of water to cities, and the navigation of rivers and canals.
As this diminution of water-supply is the result of man's acts, so also in a great degree is the remedy of control within his power, and by means of planting and with reservoirs le can often recover and maintain the advantages lost, perhaps as fully as they existed under the primeval forests.
Among the means for the advancement of forest-science in Europe, we might mention as worthy of notice, the growing interest in various societies and associations, formed for the discussion of new questions as they arise, the comparison of experience, and the promotion of that personal acquaintance so conducive to the general welfare. These meetings are usually enhanced in interest by excursions to forests affording an illustration of methods, or other subjects of practical interests. The more important of the essays and discussions, which these meetings call out, are published with their official proceedings, and through the medium of these publications, and the various journals of forestry, the more important discoveries become widely known.
Returning to the original resolution under which the Committee upon Forestry was appointed by this Association, in 1873, there
18 L'eber die Wasserabnahme in den Quellen, Flüssen und Strömen, bei gleichzeitiger Steigerung der Hochwüsser in den Culturländern, von GUSTAVUS WEX, K. K., MinisteHalrath und Oberlautier der Donauregulirung bei Wien. 4to, pp. 43, with 7 plates.
Zweite Abhandlung, etc., 4to, pp. 30, with o plates.
There are separate imprints from the Zeitschrift des ösierreichischen Ingenieur, und Architekten- l'ercins, 1973 and 1879.