On the Absorption of Certain Crystals in the Infra-red as Dependent Upon the Direction of the Plane of Polarization. By ERNEST MER

RITT.

By means of a spectro-bolometer the writer has determined the transmission curves for Quartz, Iceland Spar, and Turmalin out to a wave length of 5.5 μ. In order to detect the differences between the

absorption of the ordinary and extraordinary rays the radiation used (that of a Zirconium lamp) was polarized by reflection before passing through the crystal specimen. On account of diffuse rays from the surface of the fiuorite prism considerable difficulty was met with in obtaining a pure spectrum; a difficulty which was finally met by using two spectrometers 'in series;' i. e., the spectrum formed by one spectrometer was thrown upon the slit of another. The results show that the transmission curves of the ordinary and extraordinary rays are entirely independent in all three cases. In the case of Iceland Spar the differences between the two curves is especially marked, sharp absorption bands being present in the one curve which are entirely absent in the other. At = 3.3 μ Iceland Spar is found 2 to behave as turmalin, i. e., the ordinary ray is suppressed, while the extraordinary ray is transmitted in considerable amount. The difference between the two curves is less marked in the case of Quartz, but is very considerable with Turmalin. In the latter

case the two curves are found to intersect, and in the region lying between the points

of intersection the dechroism of turmalin is reversed.

Resonance in Transformer Circuits. By F. BEDELL and A. C. CREHORE.

In this article the writers discuss the action of a condenser in either circuit of a transformer, and develop by purely graphical methods the conditions necessary for primary resonance due to a secondary condenser, a

phenomenon to which Dr. Pupin has given the name electrical consonance. A primary circuit alone, and with no condenser, would have no natural period of oscillation; but it may have such a period when a neighboring secondary circuit contains a condenser. The elastic influence of the condenser is transferred from one circuit to the other, on account of their mutual relationship; and the natural period of the primary cir cuit depends not only upon the value of its own constants, but those of the secondary as well. There is a surging of energy back and forth between the primary circuit and the secondary condenser by intervention of their common magnetic field; the period of these surgings determines the period of the system. In addition to the graphical analysis, Drs. Bedell and Crehore subject the problem to a brief analytical treatment leading to identical results. It is shown that there are two values of the capacity of the secondary condenser which will give rise to consonance. It is pointed out that a condenser in the secondary of the transformer may compensate for the drop due to magnetic leakage; in fact, this drop may be over-compensated for, so that the secondary potential will actually rise as the transformer is loaded down.

Aside from the particular conclusions reached, the paper is of interest for the methods employed, the problem in hand illustrating well the writer's method of reciprocal points in constructing admittance and current diagrams from diagrams of impedance and electromotive forces.

On the Secular Motion of a Free Magnetic Needle, I. By L. A. BAUER.

This article forms the introduction to an important paper on the secular variation of terrestrial magnetism which will be concluded in the next number. The present article is devoted to a description of the

methods of accumulating and discussing the available data. An abstract is postponed until the appearance of the remainder of the paper.

New method of Testing the Magnetic Properties of Iron. By W. S. FRANKLIN.

In determining the curve of magnetization, the sample, in the form of a long narrow, is suspended from the arm of a balance, the legs of the being surrounded by fixed magnetizing coils. The induction may then be calculated from the weight necessary to hold the specimen in equilibrium. A novel method of determining hysteresis loss is also described. In this case the sample was in the form of a long rod, and was magnetized by a rather short coil. The rod was suspended from one part of a balance, and was weighed first while the coil was moved slowly upward and afterwards during a slow downward motion of the coil. A method is developed by which the hysteresis loss may be computed from the difference of these weights. Experimental data accompany the paper.

New Books. The following books are reviewed: RAYLEIGH. Theory of Sound, Vol. I. POINCARÉ. Les Oscillations Electriques. CARHART. University Physics.

THE JOURNAL OF COMPARATIVE NEUROLOGY.

THE Journal of Comparative Neurology for March contains three original papers. The first, Modern Algedonic Theories,' by C. L. Herrick, is a critique based primarily upon Marshall's Pain, Pleasure and Esthetics, though most of the other recent literature is reviewed in the same connection. The physiological theory of emotion finally adopted by the writer is in the main a composite drawn chiefly from the nutrition theory of Meynert, the discharge theory of Lange and James, and the theory of habit of Gilman. In brief, it is a resistance theory. When we have agreed upon the

nature of the simplest sense, pain and gratification, the foundation will have been laid for the more complex æsthetic phenomena. This foundation is believed to consist in the recognition of a special kind of neurosis for the feelings due to two classes of stimuli of a very similar but not identical kind. Given an excessive stimulus which for whatever reason freely irradiates, and pleasure is felt; given another stimulus, or the same excessive stimulus with other neural conditions which prevent irradiation and produce a summation and overflow, and pain is felt. Emotion consists (1) of general sensations of total, organic or irradiating varieties which have in common a lack of localization and, as a result of associational laws, are amalgamated more or less closely with the empirical ego; (2) of more or less explicate or implicate cognitions (perceptions, intuitions) of the relation between the cause of the sensation and our well-being; (3) the emotion is more or less closely attached to various impulsive expressions which tend in various ways to intensify the two preceding. The psychical element of emotion is essentially intellectual, and the attempt to secure a serial relation of the faculties' must be abandoned.

The second paper by M. A. Raffalovich deals with Uranism, or Congenital Sexual Inversion.' It is a plea for the early recog nition of congenital inversion in children and the proper education of such children. Inversion is no excuse for debauchery and Krafft-Ebbing's pity for the race of inverted persons is largely misplaced. The psychological history of a superior uranist is traced and commented upon at length.

In a brief paper entitled 'The Histogenesis of the Cerebellum,' C. L. Herrick notices the recent work of Dr. Shaper upon the cerebellum of teleosts and calls attention to the gratifying harmony between these results and his own studies published in 1891.

9 is the geographical latitude and c = This formula is doubly interesting just now, as it has been recently deduced empirically by Professor W. von Bezold.* This eminent investigator, when considering the mean values of the geomagnetic potential along parallels of latitude, found them subject to the simple law a = 0.330 = c. sin =

=

sin. Since cμ, and the magnetic moment, M, of the earth is equal to μ. a3, we find that von Bezold's empirical coefficient implies a value of the magnetic moment equal to 8.52 × 1025 against 8.55 × 1025 as determined by Gauss. We thus see the theoretical significance of von Bezold's factor.

Since for the case supposed the horizontal component of the intensity, H, is directed meridionally, it follows from (1) that:

we can get a fair value of the magnetic moment of the earth without the aid of the laborious Gaussian computation by simply scaling the value of H for equidistant points along a parallel of latitude from iso

dynamic charts and substituting the mean of the values thus found in (6).

Thus I get for 1885 as the mean result of the scalings along 40° N, 20° N, Equator, 20° S and 40° S, the value of 0.325 a3 for M, against 0.322 a3 resulting from the 1885 Neumayer-Petersen re-computation of the

Gaussian co-efficients.

But why should the values obtained on the assumption that the earth is uniformly magnet

transformations:

geographical axis, so nearly agree with those based upon observed quantities? It seems to me that this opens the question whether the asymmetrical distribution of land and water is the primary cause of the asymmetrical distribution of telluric magnetism, as generally supposed. Why do the 'anomalies' in the distribution so nearly cancel each other in going along a parallel of lati

*These quantities are the results of the scalings of Neumayer's charts for the points mentioned.

tude?

Does this again imply that the rotation of the magnetic earth is an important factor?

If we connect by lines all the places on the earth's surface having the same departure (with due regard to sign) from the values as computed from above formulæ we get a series of curves that converge around two foci of maximum and minimum departures. I have carried out this idea with the aid of my collected data in the case of the inclination for three epochs, 1780, 1880 and 1885. I call the curves thus obtained lines of equal departing inclination, or, briefly, isapoclinics.' It is especially remarkable that these lines close around two points not on opposite sides of the equator, but on the same side.* Their preliminary positions are:

These positions are subject to a slight revision. The main part, however, is brought out very clearly in both cases, viz.: that the chief cause of distortion of the primary symmetrical field can be represented as due to a secondary polarization approximately equatorial in direction.

I then showed that the isapoclinics obey in a remarkable degree the laws governing a magnetic system. They do not run at random. Thus, for example, the foci or poles of this secondary system fall nearly on the agonic lines of the actually observed field, and the secondary magnetic equator running roughly north and south marks out approximately the places where occurs

*Similar results have been obtained by von Bezold in the paper cited, and by A. von Tillo as seen in his preliminary paper in Comptes Rendus, Oct. 8, '94, pp. 597-599. It is very much to be hoped that von Tillo's charts will soon be published.

the maximum declination. In a word, the magnetic field which we actually observe can be nearly obtained by super-imposing a secondary equatorial field upon a primary polar one.

By comparing the maximum horizontal intensities of the the two systems, as found in the respective magnetic equators, I find that the polar field is about five to six times stronger than the secondary, and that the axis of the resultant system would make an angle of about 10° with the rotation axis.

Furthermore, the secular variation phenomena can be qualitatively explained by the shifting of just two such poles as belong to the secondary system. It cannot be explained by the disturbance of poles on opposite sides of the equator.

We should thus have to refer both the distribution and the secular variation to apparently the same kind of a polarization.

This harmonizes with the empirical conclusions at the beginning of this paper.

Since the intersection of the agonic lines with the equator fall so nearly together with the positions of the isapoclinic foci, a fair idea, perhaps, can be obtained of the shifting of these foci from the motion of the agonic lines along the equator. I find that both agonic lines have been moving westwardly along the equator for the last 300 years at the average rate of about 0.02 per an

num.

If the motion continues around the

equator at this rate the resulting period would be about 2000 years, but I do not wish to be understood as asserting that this is the secular variation period.

A possible third field, which has been made probable by Dr. A. Schmidt's beautiful researches, was also pointed out. Schmidt found, namely, that not the entire observed magnetic effect on the earth can be referred to a potential; currents that pierce the earth's surface seem to make themselves felt. Perhaps his currents can be explained thus: If an arbitrarily magnetized sphere rotates in a conducting fluid,