than for the student in any other field. It is this sense of the oneness of human history, this sympathy and understanding of men of all times, that gives the charm to his immortal Principles of geology; and in this day, when we are debating as to the use of classical training, it is well to ask what this book would have been if the Oxford element had not been there. It would perhaps have an equally valuable body of fact, but the informing spirit would have been wanting.

His power to make avail of his Oxford life was doubtless due to his keenness of appreciation of all forms of intellectual stimulus, though he took a fair rank in his college, winning second honors in classics. We see in his letters home that he has a lively interest in music, which had been an early-developed taste; for in his schoolboy days he had been the leader of a schoolboy orchestra. He is also something of a versifier; and some of his verses show a delicate fancy, though by no means a strong wing.

His first acquaintance with geology seems to have been made through Bakewell's Geology, which he found in his father's library; and that author's account of the earth's antiquity appears to have first aroused his curiosity to know more of the subject. While he was at Oxford, Buckland was at the height of his singular popularity. His lectures affirmed this early-acquired taste. His first geological journey was to Yarmouth, where he saw the great cutting power of the sea on that soft-cliffed coast. In the same year a journey to Staffa, of which his journal is given, served to pos

a matter that is one of the most transparent things in their history. The motion of the glaciers is not seen to be a problem: yet his critical spirit is awake; for, one of his party finding in an album the lines,

"Mont Blanc is the monarch of mountains:
They crowned him long ago,
Enthroned in ice, with robes of clouds,
And diadem of snow,".

he well says,
"It contains more real poetry
than I thought could be found in all the albums
of Europe.' He did not recognize that they,
a little garbled, were from Byron's Manfred,
which had been published the year before. It
may be that it shows us the place of birth of
these the finest lines in that strange dramatic
poem. Despite the veil that hid the deeper
secrets of the Alps from his eyes, his good
fortune showed him many things which served
to lead his mind to the notion that the present
forces of the earth are strong enough to ex-
plain the past. He saw the Goldau éboulement,
or landslide, then but a dozen years old; and
in the Rhone valley he beheld the frightful
marks of the flood which poured from the lake
formed by the Glacier de Bagne but six weeks
before his coming.

GEODESY.

Length of a nautical mile.-In common parlance, the length of a nautical mile is considered as a minute of latitude,' without any consideration of the range of value included within this definition. A paper upon this subject by Prof. J. E. Hilgard, superintendent of the Coast and geodetic survey, has just been published. It gives the values of one minute under nine different definitions. The values are based upon the elements of the Clarke spheroid. One minute of latitude at the poles = 1,861.655 metres = 6,107.85 feet; one minute of latitude at the equator = 1,842.787 metres = 6,045.95 feet; one minute on the equator (considering it as a circle) = 1,855.345 metres = 6,087.15 feet.

As adopted by the Coast and geodetic survey and by the Hydrographic office, a nautical mile is onesixtieth part of the length of a degree on the great circle of a sphere whose surface is equal to the surface of the earth. Using the Clarke spheroid, this definition gives a nautical mile = 1,853.248 metres = = 6,080.

27 feet. This value closely corresponds with the English admiralty knot of 6,080 feet. (Rep. U.S. coast surv., 1881, app. 12.) H. W. B. [172 Night signals for geodetic work (by Mr. O. S. Wilson of the N. Y. state survey). · Owing to the small number of days during any season when the air is in good condition for sighting points more than twenty-five miles distant, and the few hours during even good-seeing days available for such geodetic work, especially in measuring horizontal angles, it is important not only to use to the best advantage what daylight is available, but also if possible to lengthen every good-seeing day. Hence any device for continuing work during clear nights is of great value. For this purpose electric lights were used on the triangulation carried across the Mediterranean in 1879 by the French and Spanish governments, with remarkably good results; the error of closure of a triangle being but a trifle over one second of arc. Some of these lines were the longest ever sighted for geodetic purposes, one of them being 167.7 miles. The burning

of magnesium-wire, fed by clock-work, in the focus of a parabolic reflector, gives an excellent light; but this, like the electric light, is too expensive for ordinary geodetic uses. The U.S. coast and geodetic survey has used kerosene student-lamps in place of the magnesium wire in connection with parabolic reflectors, on lines of twenty-five miles, with satisfactory results. At a station in Virginia, occupied by C. O. Boutelle, angles measured by day were duplicated at night, and the mean error of the night-work was only two-thirds of that done in the daytime.

In 1881 Mr. Wilson procured a small locomotive head-light with a twelve-inch reflector, and two cast semaphore lenses, one twelve and the other fourteen inches in diameter. Each of these lenses was mounted in the end of a box in which a kerosene-lamp with a 'mammoth-leader' burner was placed at the focus of the lens. These three lights, being set near each other, were readily seen through a small telescope at a distance of thirty-five miles, and little if any difference of brilliancy was detected. The magnesium apparatus and the locomotive head-light each cost about thirty-five dollars; but the magnesium wire being expensive, and this light requiring constant attention, the cost of maintaining it is several times greater than that of operating the locomotive headlight. The cost of a semaphore lens mounted in a galvanized-iron box is from ten to fifteen dollars, according to the size. The expense of maintaining it is small, not more than fifty cents a night, kerosene being cheap, and no attention being required after the lamp has been properly trimmed, and lighted a short time. These lamps have been seen by the naked eye at a distance of forty miles.

In order to diminish as little as possible the light in the field of the telescope, a series of mirrors was so arranged upon and within the tube as to illuminate the wires, and leave the field dark. It is believed that this has not before been done with small telescopes, the one used in this instance having an aperture of only two and a half inches. Kerosene handlamps, protected for use in the wind, were devised and successfully used for reading the circle and illuminating the wires. The night observations thus made at state survey stations in 1882 were apparently fully equal to those taken in the daytime by means of heliotrope signals; and about half of the primary observations were actually made in the time thus saved.

For readily finding a distant signal light at night, a reference lantern was placed a short distance from the observing-station. By this, rough settings were made for the signal-light needed, which could then be brought into view by a slight vertical movement of the telescope. — (Alb. inst.; meeting Jan. 30.) [173

MATHEMATICS.

Conjugate quadrangles.-M. Stephanos, in seeking to generalize a kinematical proposition announced by M. Tchekychef in his memoir Sur les plus simples systèmes articulés qui fournissent un mouvement rectiligne approximatif au quatrième et au cinquième ordre (St. Petersburgh, 1881), has arrived at a number of properties of conjugate quadrangles. M. Stephanos defines conjugate quadrangles as being formed by two systems of four points (A1, A2, A3, A4), (B1, B2, B3, B4), when, being placed upon a plane in any manner, without altering their respective dimensions, the corresponding points (A and B) form four pairs of conjugate points with respect to a circle. There is an infinite number of quadrangles B, conjugate to a given quadrangle A; and all of the B-quadrangles are similar one to another. If A and B are two conjugate quadrangles, the areas of the triangles A2, A3,

A, etc., are proportional to the areas of the triangles B2, B3, B4, etc. The respective ratios are denoted by 2, 22:23:24 with 220. 21, 22, and 23 are given in terms of the cotangents of the angles of the triangles A2, A3, A4, and B2, B3, B4. Considering two conjugate quadrangles A and B situated in the same plane, and denoting by P1, P2, P3, P4, the distances between corresponding summits, it is shown, that, whatever be the relative positions of the two quadrangles in the same plane, we have always the relation:

2

4

λ 1 p1 2 + λą p2 2 + 23 P32 + λ 4 P12 = C; where C is a constant depending only on the dimensions of the two quadrangles. — (Comptes rendus, Oct. 16, 1882.) T. C. [174

Conical umbilics. - The following is taken from a report by MM. Bouquet and Jordan upon a memoir presented by M. de Salvert to the Academy of sciences. M. de Salvert studies the sections of a surface F (x, y, z) 0, in those singular points where the tangent cone is of the second degree by planes passing through the axis of the tangent cone. Each section consists of two branches crossing at the multiple point, and having for tangents in this point the two opposite generatrices of the cone: it is proposed to find the curvature of these two branches. The author finds a formula for this curvature, of which he shows the analogy to the known expression for the determination of the radii of curvature of a normal section at an ordinary point. An application is made to the case of the wave surface, and then the author seeks the necessary conditions that the assumed point shall be a conical umbilic: i.e., a point such, 1°, that the tangent cone shall be one of revolution; 2°, that the branches of the curve which correspond to its different generatrices shall all have the same curvature. The first of these conditions leads only to known results; the second introduces six new equations involving the third derivatives of F. (Comptes rendus, Jan. 8, 1883.) T. C. [175

Subdeterminants of a symmetric system. — In July, 1882, Prof. Kronecker presented to the Berlin academy a memoir in which he established certain linear relations between the subdeterminants (minors) of a symmetric system. M. Runge deals with the same subject in the present paper, and claims to show that relations found by Kronecker are the only ones existing, inasmuch as all others can be expressed by linear combinations of Kronecker's relations. also finds a method for the determination of a system of linearly independent subdeterminants in terms of which all the remaining subdeterminants of the same order are linearly expressible. — (Journ. reine angew. math., xciii. 1882.) T. C. [176

8

He

Ternary quartics. In continuation of his researches on the ternary quartic x1, x2 + x2 x3 + x 38 x 1, and on systems of conics, Prof. Gordan discusses the typical representation of the system formed by this quartic and a conic. He finds that the coefficients in this representation are entire functions of only twelve simultaneous invariants, five of which are expressible as rational functions of the other seven, which are themselves connected by an algebraic equation of the sixth degree; and all these relations are explicitly given. These relations reduce the number of independent invariants to six, which is evidently the actual number. The last part of the article is devoted to the solution of the converse problem of determining a conic when the invariants above mentioned are given. (Math. ann., xxiv. 1882.) F. F. [177

Equations of the seventh degree. In this paper, Prof. Gordan applies the results obtained by him

in the paper noticed above to the solution of those equations of the seventh degree in which a certain function of the roots is unaltered by a group of 168 substitutions. Such equations arise in connection with the modular equations of elliptic functions, and had been previously studied by Hermite, Klein, and others. Klein had pointed out that their treatment should be made to depend upon the investigation of the system formed by a certain ternary quartic, which is transformed into itself by a group of 168 substitutions and an arbitrary conic. It was this which led Gordan to undertake his researches upon that system. In the present paper he forms certain seven-valued functions of the coefficients of the arbitrary conic; the sums of the powers of these functions are, in virtue of a general theorem previously proved, rationally expressible in terms of the fundamental invariants of the system; and the fundamental invariants are rationally expressible in terms of the sums of the powers. The seven quantities, then, being regarded as the roots of a given equation, the invariants in question become known, and the solution of the equation is reduced to the problem of finding the coefficients of the arbitrary conic when the invariants are given; the solution of which problem is contained in the preceding paper (No. 177). The whole investigation is extremely long and difficult; and Prof. Gordan announces his intention of recasting the method by which he obtained his results, and giving a presentation of them in which every trace of the way in which they were reached shall have disappeared.'-(Math. ann., xx. 4, 1882.) F. F. [178 PHYSICS.

Acoustics.

Sounds produced by flow of liquids. - Tito Martini has continued the researches of Savart upon the sound produced by a stream flowing through a circular hole at the lower end of a long tube containing liquid. He finds that the pitch does not change gradually, but that a definite number of distinct notes are heard successively as the liquid column shortens by the outflow. The pitch depends on the length of the liquid column and on the velocity of efflux. The number of vibrations is proportional to the velocity of efflux, and the sound is pure only when the sound of the vein is one of the proper sounds of the liquid column.

A column of constant length gives notes in a harmonic series. When the sound is re-enforced by the column of air above, it becomes quite loud. If the walls of the tube are prevented from vibrating, the sound ceases. The relative velocity of sound in different liquids may be determined by finding the lengths of the columns of liquid which give the same note, and the results given in the paper agree very well with determinations by other methods. (Journal physique, Nov., 1882.) C. R. C.

[179

-

[180

Determination of rate of tuning-forks. Michelson has devised a new stroboscopic method, in which a fork- for example, an utą (No. 1)—is compared with a second ut (No. 2), kept in vibration by electro-magnets, and which last fork is compared directly with the seconds pendulum. The whole number of vibrations of fork No. 2 is supposed to be known. The fractions are found as follows: one prong of the fork carries a mirror; and a few feet in front of this is placed a Geissler tube, illuminated once a

second, as the circuit of the induction coil in connection with it is broken by the pendulum. The image of the tube itself in the mirror is a broad band, against which the narrow flash is projected. The number of flashes between their recurrence in two similar positions on the broad image of the tube shows the number of vibrations per second to be added to or subtracted from the known whole number. 1 α

Thus, if there are a flashes in one period, 128 is

the true rate. As fork No. 2 vibrates continuously, great accuracy can be secured. A mercury globule was used in connection with the pendulum to complete the circuit; and, by means of a relay, a break was produced in the primary circuit of the induction coil. A very constant battery must be used with the electro-magnets of the fork. The method may be simplified by dispensing with the electric fork, and placing the fork to be rated vertically, and with one edge in the focus of a microscope with cross-hairs. The Geissler tube is placed horizontally behind the fork; and the positions of the edge of the fork with reference to the cross-hairs are noted. A table of measurements is given. (Amer. journ. sc., Jan., 1883.) C. R. C. [181

Experiments with resonance boxes. At a recent meeting of the Berlin physical society, Prof. Christiani showed a mi fork, which placed on its box gave a maximum of tone when one side rather than the other was turned to the mouth of the box. The action scemed to be due to the box rather than to the fork, though this had been rusted and retuned. It was also found that a singing flame tuned to mi was silenced when a mis resonating box was placed horizontally with its mouth at the top of the tube, while if the corresponding fork was placed on the box no such effect occurred. The same action was noticed with a resonator; the flame being silenced if this was in tune with the flame, but not otherwise. ― (Nature, Jan. 4, 1883.) C. R. C. [182

Whiteness of various sources of light. - The results of a series of observations with an instrument devised by Helmholtz, and by him named 'lenkoscope,' is given by A. König. The general principle upon which the instrument depends is the following: A white surface is illuminated by the light to be tested; and two adjacent images of this surface, polarized at right angles to each other, are observed through a Nicol's prism and a certain thickness of quartz cut perpendicular to the axis. With such an arrangement, the two surfaces would appear of complementary colors, the tints being determined by the azimuth of the Nicol, and the degree of saturation by the thinness of the quartz plate. With a thin plate the two portions of the field would always be very unlike; with a very thick plate, always nearly white and alike; and, finally, with a plate of intermediate thickness, the similarity would depend upon the azimuth of the Nicol. The value of the azimuth which yields the greatest similarity when a plate 20 mm. thick was employed-and this angle must evidently depend upon the color of the light used — was taken as an arbitrary measure of the whiteness of the light. The table characterizing various fa

[185

Polarization of diffracted light. The investigation here described relates to the modification which plane polarized light undergoes in diffraction by a reflecting grating of glass, of collodion, or of speculum metal. It is thus closely allied to Frühlich's research, though of a more general character. The author, W. König, found that within the range of deviation, where elliptical polarization was marked, the determinations of azimuth were not very satisfactory: hence attention was given chiefly to difference of phase in the two components. This difference was measured by a Babinet compensator. All of the results were in satisfactory accordance with Réthy's theory of spherical polarized wave-surfaces, by which he explained the phenomena observed by Fröhlich. The experiments go far to reconcile the contradictory results, obtained by experimenters, who, following Stokes, have attempted thus to determine the relation of the plane of polarization to that of vibration; but at the same time Réthy's theory seems to end all hope of deciding this interesting point by the most promising means hitherto suggested. (Wied. ann., 1882, 1016.) [186

C. S. II.

Elliptic double refraction.-E. Lommel develops his theory of refraction, to apply to the case of propagation of light-waves in a medium which rotates the plane of polarization. The equations yield a form of Biot's law for rotation involving the index of refraction, which corresponds well with observation. (Carl's repert., xviii. 673.) [187 Galileo's telescope. An extended discussion of the theory of this form of telescope, by W. Pscheidl. ― (Carl's repert., xviii. 686.) C. s. H. [188

(Photography.)

C. S. II.

Photography as applied to animal locomotion. -A simple method of studying photographically the movements of animals is described by M. G. Demeny. In front of the camera is placed a rapidly revolving disk, containing a narrow sectorial window. A white animal is selected, which moves in the sun before a very black background, best an opening in a darkened shed. The exposures with sensitive plates may be reduced to the Toon part of a second, the intervening intervals being sufficiently long so that the images shall not be superposed. By knowing the rate of the disk, the speed of the animal may be measured from the negative. If the plate is caused to move in the opposite direction to the image of the animal, the exposures may be made more frequently without fear of superposition, as has been done by M. Marey in his photographic sun' (La Nature, April 22, 1882). By having a number of windows in the disk, the course of small, rapidly moving objects may be studfed: for example, the trajectory of a white stone thrown from the hand, or a white paper attached to the circumference of a carriage-wheel. - (Journ. de phys., Nov., 1882.) W. H. P. [189

Heat.

73

Production of low temperatures. — After comparing the various methods for producing low temperatures, Mr. Rawbotham concludes that the method by the evaporation of ammonia is the best; ammonia being preferable to other liquids, chiefly on account of its high latent heat, and high pressure at low temperatures. (Journ. Frankl. inst., lxxxv. 2.) C. B. P. [190

Heat of solution and of dilution of perchloric acid. — In his researches on the oxyacids of chlorine, M. Berthelot has been conducted to the study of the heat of formation of perchloric acid. The solution of the liquid monohydrated acid in one hundred times its weight of water at 19° sets free +20.3 cal. This enormous heat, which exceeds that of all the common monohydrated acids, explains the extreme difference which exists between the action of this acid in solution, and the action of the monohydrated acid. It is found that the molecular specific heats of solutions of perchloric acid, between 40° and 15°, can be represented by the formula,

273.8 742.2

The heats of dilution of the acid when in different degrees of solution can be represented by a peculiar hyperbolic curve, similar to that already found for nitric acid. (Ann. chim. phys., Oct., 1882.) C. B. P.

[191

Specific heat. - A modified form of Regnault's apparatus has been employed by M. W. Longuinine for the determination of specific heats. By the revolution of the cylinder the body is dropped through the floor of the chamber, in which it is heated, through a space of 0.08m. into the calorimeter. In order to obtain accurate results, it is necessary for the substance to have a spherical form. When powders and similar substances are used, they are placed in a sphere of brass, the specific heat and weight of which are known. This apparatus appears to give more uniform results than Regnault's.—(Ann. chim. phys., Nov., 1882.) C. B. P.

[192

Change of chemical constitution by heat.Herr E. Wiedman has shown that a number of salts containing water undergo chemical change when heated, though the temperature is below that of fusion. He has thus found two new modifications of the sulphates of zinc and magnesium. The result has interesting bearings in the determinations of tension, and of the heat of solution. (Wied. ann., No. 12.) C. B. P. [193

Electricity.

A determination of the ohm in absolute measure. Notice was given by A. L. Kimball of the proposed redetermination of the ohm; the method to be used being the same as that used by Prof. Rowland in 1876, changes being made in the character and arrangement of the apparatus so as to avoid, so far as possible, the repetition of constant errors. A short account was given of the nature and importance. of absolute measurement in general, in which the derived units are all based on the fundamental units of length, time, and mass, and derived directly from them. The nature of the unit of electrical resistance was then noticed, and attention called to the fact, that, in the electro-magnetic system of units, the unit of resistance bears to the units of length and time the relation of a velocity. Mention was made of the most noteworthy methods that have been used in determining the value of resistance in absolute measure, attention being called to the manner in which

the units of length and time entered into the experiments. (Johns Hopk. univ. sc. assoc.; meeting Jan. 3.)

[194 ENGINEERING. Automatic inspection of railways. The precise methods of modern physical research are fast invading the various fields of practical science, and enabling us to be more and more independent of guesswork every year. Nothing illustrates this more forcibly than Mr. P. H. Dudley's dynamometer car, which is drawn from one end to the other of any railway, and, as it goes, records automatically every imperfection existing in the track, and at the end of the trip presents a long roll of paper which is a complete telltale in regard to the exact state of the road. Every bad joint, every defective rail, every lack of correct alignment, either vertical or horizontal, is shown upon the diagram in such a manner as not only to indicate the precise location of the defect, but at the same time to suggest the remedy. The dynamometer car has been employed upon a great many of our more important railroads, with the most satisfactory results. G. L. V.

[195

Railway management as a science. Art first, and science afterwards, has been the rule in all technological pursuits, to which railways are no exception. We are fast accumulating sufficient data to show that there is such a thing as a science of railway operation; and just as soon as this fact is recognized, this science will find a place in our technical schools. The Archiv für eisenbahnwesen, a periodical issued by the Prussian ministry of public works, announces that there will be in the winter semester of the universities of Berlin and Breslau, courses of lectures on railroad operation, including station and train service, signalling, organization and duties of employees, and railway mechanism; and also lectures on railway administration, including the arrangement of rates and fares, the discussion of wages, and railway statistics. A third course will be on railway law, and a fourth on railway transportation as a branch of political economy. -G. L. V. [196

CHEMISTRY.

Congelation of solvents. In experiments upon the point of congelation of water, formic acid, acetic acid, benzol, nitro-benzol, and ethylen dibromide, M. Raoult tried the action of each solvent upon two hundred other substances. A solution of one grm. substance in 100 grms. of the solvent gave results from which the following law was deduced: A molecule of any substance whatever, when dissolved in 100 molecules of any liquid of a different nature, lowers the point of congelation of the liquid 0°.62,

- a value nearly constant for different solvents. (Comptes rendus, xcv. 1030.)

C. F. M.

[199 Formation of active oxygen.. Results obtained by Moritz Traube show that ozone is not produced by hydrogen in statu nascendi. The hypothesis of Hoppe-Seyler, that chemical processes which take place within the bodies of animals are identical with those resulting from putrefaction, and depend upon the presence of ozone produced by nascent hydrogen, must therefore be incorrect. In support of this hypothesis, Hoppe-Seyler asserted that nascent hydrogen from palladium-hydrogen would convert oxygen into its active condition. The author finds that hydrogen is not evolved from the alloy at ordinary temperatures, and that instead of ozone, in presence of water, hydrogen peroxide is formed. Other results seem to indicate that hydrogen peroxide is a product of reduction rather than of oxidation. (Berichte deutsch. chem. gesellsch., xv. 2421.)

C. F. M.

[200

Influence of pressure on the speed of chemical action. - Prof. R. B. Warder made the following remarks: "Menschutkin1 has recently published his experiments on the decomposition of tertiary amylacetate by heating in sealed tubes. At 155° C., while the pressure was gradually increased by the formation of amylene, the speed of the reaction was found to increase until about half the ether was decomposed. Menschutkin's graphical representation of the progress of the reaction has a point of inflection at this stage. This fully accords with the theory of action of mass' if we assume that this reaction, like many others, is promoted by pressure.

If the speed of the reaction is directly proportional to the pressure, and if the increase in pressure is proportional to the amylene generated, the course of the reaction should be represented by the equation, At.

log

- log

и m-u

Where u is the quantity of ether still present at any moment, to be eventually decomposed within the limit of the reaction, u, is the initial value of u; t is the time of action; o is the ratio of initial

m

m

to final pressure; and A is a constant, dependent upon the actual pressure, as well as the absolute coefficient of speed.

By making m=1.01uo, and A = 0.04, we obtain an equation which pretty closely agrees with Menschutkin's curve. -(Ohio mech. inst.; sect. chem. phys.; meeting Jan. 18.) [201

(Organic.)

Caffeine, theobromine, xanthine, and guanine. -In an extended investigation upon the constitution of these substances, Emil Fischer examined many of their derivatives and decomposition-products. Öxidation of caffeine with hydrochloric acid and potassium chlorate gave methylurea and amalic acid. This acid, without doubt, was formed directly from dimethylalloxan, in a manner analogous to the formation of alloxantine by heating alloxan with hydrochloric acid. By oxidation with nitric acid, amalic acid was converted into dimethylalloxantine, which formed cholestrophan by further oxidation. In the oxidation of theobromine, the resulting methylalloxan was immediately changed into the corresponding alloxautine, which gave methylparabanic acid by oxidation. Methylurea also was identified as a product of the oxidation of theobromine. As the decomposition-products of xanthine, alloxan was 1 Ber. chem. gesellsch. xv., 2512-2518.