and is no decided improvement upon those of Plantamour, Bauernfeind, and Ruhlmann.

As a perfect specimen of what a hand-book should be we recommend Dr. Paul Schreiber's "Handbuch der barometrischen Höhen-Messungen" (Weimar, 1877). The discussion of instruments and errors, formulæ and methods, leaves nothing more to be desired, as was to be expected from one who has had so much experience and is so high an authority.

AGRICULTURE AND FORESTRY.

The subject of forest-culture and the attending study of climate has of late years received increased attention. To the national bureaus of Switzerland and Bavaria we have now to add Prussia; this latter is under the direction of Dr. A. Muttrich, of the College of Forestry at Neustadt-Eberswalde; thirteen stations are occupied under him, and the annual reports for 1875 and 1876 have appeared during 1877.

Dr. F. B. Hough, formerly meteorologist to the State of New York, has about completed an extensive report to the United States Senate on Forestry; it is hoped that our government will give this subject special attention.

The influence of pine forests upon rainfall and atmospheric moisture has been investigated by Fautrat, who concludes that the pines have, even more than the leaf-bearing trees, the property of condensing the aqueous vapor; the atmosphere is also moister and the evaporation far less.

Fautrat has also studied the climatological influences of leafy and resinous woods. He finds that above the pines the maximum temperatures are higher and the minimum lower than outside of the forest, but in leafy forests the radiation of heat is counteracted by other phenomena producing heat. Within forests, especially of resinous woods, there is less ozone than in open ground.

A contribution to the relation between meteorology and agriculture is made by Professor Wolling, of the Agricultural Experimental School at Munich, in his "Investigation into the Temperature and Evaporation in Different Kinds of Soil."

CLIMATE AND HYGIENE.

The connection between climate and disease is treated of by Dr. J. Schreiber in a characteristically clear and interest

ing address, in which he takes the advanced position to which all recent researches are unmistakably pointing, viz., that moisture and temperature and barometric pressure are for many diseases, such as consumption, yellow fever, etc., not the important factors to be considered by medical men in locating sanitariums, but that, on the contrary, these are but incidental to the more important question, "Is the air of the locality free from injurious organic dusts and germs?" He says, "The term 'climatic,' which we have thus far imagined to refer to some indefinite specific concerning which we could give no account, is become exceedingly clear and simple; it means, above all, air which is pure, containing no miasma, no organic or inorganic mixture, in which, therefore, rain or snow occurs" frequently enough to continually keep it washed and pure. If meteorologists would contribute to our knowledge of the sanitary relations of the atmosphere, they must also observe the organic dust floating therein according to the methods that are now well understood by microscopists.

The influence of high altitudes, or rather of diminished atmospheric pressure, upon health, and especially its curative. influence in diseases of the lungs, has received an increasing amount of attention. Comprehensive memoirs upon this subject have been published by Denison, of Denver, Colorado, and Gleitsmann, of North Carolina. The volume by Dr. Bert on "Atmospheric Pressure and Animal Life " (Paris, 1876) seems to have turned attention strongly to this matter.

The general influence of climate on consumption was the subject of a Lettsomian lecture by C. T. Williams.

CLIMATE AND GEOLOGY.

The general relations between the condition of the surface of the earth and atmospheric conditions, especially the winds, is elaborately treated of by Czerny in "Die Wirkung des Windes," etc., in Petermann's Geographische Mittheilungen Ergänzungsheft 48. Most remarkable, however, is the view ably defended by Richthofen, that the immense "loess" deposit of China is the result of subaerial denudation.

From his experiments on the capillarity of soils, Klenze finds that with earths of the same degree of comminution the composition is of importance; thus quartz conducts faster than

kaolin. With different degrees of comminution, he finds the water rises higher in the soil in proportion as the particles of soil are finer: fineness is more important than chemical constitution. Up to a certain height the capillary elevation. of water is slower as the soil is finer, but after that the ratio is reversed. The water rises more slowly in proportion to the number of non-capillary spaces, but it rises higher as the non-capillary spaces are fewer. The presence of salts in the water retards the capillary conduction in proportion to the concentration of the solution. For fine soils there seems no limit to the height to which water will eventually attain. The capillary action takes place downwards very nearly the same as upwards. The capacity of the soil when saturated by capillary action increases with the fineness of the particles nearly the same in loose as fine soil if only a few non-capillary spaces occur, but materially less when such spaces are numerous.

The influence of low pressure upon human life and health has been investigated by Mermod. His conclusions are: (1) The regular and prolonged sojourn at successively higher and higher elevations is accompanied by an acceleration of the pulse. (2) The regular and prolonged sojourn at 1100 meters above the level of the sea is not accompanied by any acceleration of the respiratory movements. From these two laws the following results can be drawn, and are confirmed by observation. (3) The mean fraction, representing the ratio between the frequency of respiration and the beatings of the heart, always diminishes in proportion as one dwells at stations more elevated above the sea-level. (4) The temperature of the body does not sensibly diminish by transportation from residence at 142 to 1100 meters altitude. (5) Far from finding in the weight of the air breathed an increase in proportion as we dwell higher, there is rather a diminution. (6) The absolute and relative quantity of carbonic acid exhaled by the lungs increases by the removal to higher elevations, and that with an unchanged rate of respiration and a diminution of the weight of the respired air.

PHYSICS.

By GEORGE F. BARKER,

PROFESSOR OF PHYSIOS IN THE UNIVERSITY OF PENNSYLVANIA, PHILADELPHIA.

GENERAL.

The activity in Physical Science during 1877 has been fully equal to that of any former year. The distinguished physicist, Professor Sir William Thomson, in his address as president of the Mathematical and Physical Section of the British Association at the meeting at Glasgow, September, 1876, after speaking in laudatory terms of Americans, American science, and the Centennial, discusses anew the question of the solidity of the earth, and gives the results of new calculations from precession and nutation to prove it, undertaken in consequence of suggestions made to him by Professor Newcomb, of Washington.

Main has claimed-and with justice too, apparently-with reference to the discussion in England concerning the meaning of the word "force," that it was used by Newton as the English equivalent of the Latin word vis, and not alone of vis impressa, as is maintained by Tait. When Newton wrote vis insita, vis motrix, vis gravitatis, vis centrifuga, he must have had in mind for each of these their ordinary English equivalents, in which vis always means force. This use of the word is by no means loose and inaccurate; it is rather general and comprehensive. Main closes by saying: "Some English mathematicians wish to have this valuable word all to themselves for a special technical sense; Newton claims no such monopoly, nor is it claimed at all by foreign mathematicians, nor conceded by metaphysicians; nor is the claim to this monopoly likely to be conceded until a better title to it has been shown.”

Matthey has presented to the French Academy the bar of platinum-iridium made for the four-meter standard, to the order of the International Geodetic Association. To make it, 450 ounces of platinum and 55 of iridium were

melted by a jet of coal-gas and oxygen, and cast into an ingot. Five ingots thus made were cut into small fragments by hydraulic pressure, melted together and kept in fusion for a long time, and then poured into a single ingot. This was forged and rolled into bars, which were then fused in rectangular troughs. After forging, the metal appeared homogeneous, and gave a bar 35 centimeters long, 7.5 wide, and 2.5 thick, the density of which at 0° was 21.522. A third was cut off, and the other two thirds again forged into a bar 95 centimeters long, 2.5 centimeters wide, and 2 centimeters thick, having a density of 21.648. This was rolled between polished rolls nearly to the dimensions required, 4.1 meters long, 2.1 centimeters wide, and 5 millimeters thick, and then finished by passing it through a steel draw-plate. During all these rolling operations it was repeatedly annealed. In some remarks on this paper, H. Sainte-Claire Deville gave the results of his analysis of this alloy. He found 89.42 of platinum, 10.22 of iridium, 0.16 of rhodium, 0.10 of ruthenium, and 0.06 of iron. The density calculated from this composition is 21.51; that actually observed by him, 21.515. The third cut off of the bar above mentioned has been made by Deville into two tubes more than a meter long, closed at both ends, one of which has a capacity of more than a liter, designed for the determination of boiling-points. Both tubes carry marks exactly one meter apart. One of them communicates by means of a capillary tube with a Regnault manometer, and acts as an air thermometer; the pressure being determined by the manometer and the temperature by the elongation of the tube, compared with its fellow kept in ice, the expansion-coefficient being known.

MECHANICS.

1. Of Solids.

In Mechanics, Tschechowitsch has described a universal apparatus for illustrating the elementary laws of mechanics in class instruction. By its means the parallelogram of forces, resolution and composition of forces, the action of parallel and of oblique forces, action and reaction, the principles of the lever and of the balance, can be very fully de