that the slave holders have lost the power of feeding themselves; but this is not unexampled in human affairs. Surely many a fine lady might starve outright in a place with no provender but live fowls and unthreshed wheat and water, no utensils but dry sticks and a few stones. Yet we know that savages of far lower wit could kill and pluck the fowls and get fire, spit and roast them, crush the wheat between the stones and make a damper cook it in the embers. This is a case of the loss of the power of self help by peculiar education, and if we admit this explanation for the fine lady we have no right to reject it for the slave holding ant.

I am aware that I have not dealt exhaustively with the whole question of social insects. There are lots of cruxes in their manners and customs, and especially in the manifold forms that occur in one and the same species. Why, for instance, worse food and a narrower cell should make a fertilized bee's egg become a sterile worker instead of a queen, no one knows; and the problems presented among ants are far more difficult and complicated. But it is as well to take stock frequently of our speculations, and to place our certain realized assets to the credit side, even though we have to keep most of our accounts open indefinitely. MARCUS HARTOG.

QUEEN'S COLLEGE, CORK.

THE PROPER SCIENTIFIC NAME FOR

BREWER'S MOLE.

THERE are three species of moles in the Eastern States, the Star-nosed mole, Condylura cristata, the common or Shrew mole, Scalops aquaticus, and a third less familiar species known as Brewer's mole, or the Hairy-tailed mole. It is to this last species that my remarks relate. It was described by Bachman in 1842 in the Boston Journal of Natural History (vol. 4, page 32) under the name of Scalops breweri, and was cited under that designation until 1879, when Dr. Coues

proposed to change the specific name to americanus. This proposition was based on the fact that in Harlan's Fauna Americana, published in 1825, the name 'Talpa americana, black mole, Bartram's manuscript notes,' occurs in synonymy at the head of a description which Dr. Coues thought might be in part, at least, applicable to the species under consideration.

I find, however, that this is a literal translation of Desmarest's description of the European mole, Talpa europæa, with no additions whatever, and no other alteration than the omission of a word or sentence here and there. It is evident, therefore, that Harlan included nothing from Bartram's manuscript, whatever it may have contained, and that the name Talpa americana has no validity.

It will be necessary to return to the specific name breweri. I recently separated Brewer's mole as the representative of a distinct genus, which I called Parascalops. If this distinction be accepted, the proper name of the species will be Parascalops breweri (Bachman).

FREDERICK W. TRUE.

U. S. NATIONAL MUSEUM.

THE AMERICAN FOLK-LORE SOCIETY.

THE annual meeting of the Society was held at the Columbian University, Washington, December 27th and 28th. Owing to a death in his family, the President, Dr. Alcee Fortier, of Louisiana, was prevented from attending.

The Secretary, Mr. W. W. Newell, submitted a report in which he detailed the publications of the Society for the year. These included two volumes of 'Folk Tales of Angola,' prepared by Heli Chatelain, late United States commercial agent at Loanda, West Africa, and papers by various wellknown authors as follows: Notes on the folk-lore of the mountain whites of the Alleghanies,' J. Hampton Porter; Three

epitaphs of the seventeenth century,' Sarah A. P. Andrews; Popular medicine, customs and superstitions of the Rio Grande,' Capt. John G. Bourke; 'Plantation courtship,' Frank D. Banks; 'Retrospect of the folk-lore of the Columbian Exposition,' Stewart Culin; Eskimo tales and songs,' Franz Boaz; 'Popular American Plant Names,' Fannie D. Bergen.

A large number of papers were read before the Society and discussed by the members present. The first was by Dr. Washington Matthews, entitled 'A Navaho Myth,' which related in detail one of the sacred legends of the tribe.

Capt. R. R. Moten then read a paper on 'Negro folk-songs,' in which he spoke of natural musical tendencies of the colored race and reviewed a number of the old songs of the South before the war. Negro music, he said, might be divided into three kinds, that rendered while working, a different kind for idle hours, and a third and more dignified sort used for worship. Capt. Moten said the general public had but little idea of the old negro music, and that many of the so-called negro songs rendered by white men in minstrel performances were abortions. There were some old familiar melodies, however, which were true to nature, and full of inspiration.

A quartet of colored men was present, and sang a number of negro songs illustrating the points brought out by Capt. Moten.

Several speakers dwelt upon the important question of the diffusion of folk-tales and the explanation of striking similarities found in localities widely apart. Mr. W. W. Newell was inclined to explain such by theories of transmission; while Major J. W. Powell and Dr. D. G. Brinton, both of whom had papers on closely related topics, leaned toward the anthropologic' explanation, which regards those similarities as the outgrowth of the unity of human psychological nature and methods.

Dr. J. W. Fewkes gave a detailed description of the figures in the ancient Maya manuscript known as the Cortesian Codex.' Other papers presented were: 'Kwapa folk-lore,' Dr. J. Owen Dorsey; 'Korean Children's games,' Stewart Culin; 'Burial and holiday customs and beliefs of the Irish peasantry,' Mrs. Fanny D. Bergen; 'Bibliography of the folk-lore of Peru,' Dr. Geo. A. Dorsey; Mental development as illustrated by folk-lore,' Mrs. Helen Douglass; The game of goose with examples from England, Holland, Germany and Italy,' Dr. H. Carrington Bolton; 'The Swastika," Dr. Thomas Wilson; 'Folk-food of New Mexico,' Capt. John G. Bourke, U. S. A.; 'Opportunities of ethnological investigation on the eastern coast of Yucatan,' Marshall H. Saville; Two Ojibway tales,' Homer H. Kidder.

The officers elected for the ensuing year were President, Dr. Washington Matthews; Vice Presidents, Rev. J. Owen Dorsey, Captain John G. Bourke, U. S. A.; Permanent Secretary, William Wells Newell, Cambridge, Mass.; Corresponding Secretary, J. Walter Fewkes, Boston, Mass.; Treasurer, John H. Hinton, New York, N. Y.; Curator, Stewart Culin, Philadelphia, Pa. D. G. BRINTON.

UNIVERSITY OF PENNSYLVANIA.

SCIENTIFIC LITERATURE.

Les oscillations électriques.-H. POINCARÉ, Membre de l'Institut. Paris, George Carré, 1894.

This work contains, briefly stated, a clear mathematical discussion of the general features of the Faraday-Maxwell electromagnetic theory in Hertzian form, and of those special problems bearing upon this theory which are of particular interest to the experimentalist. The mathematical solution of these problems is compared carefully with the results obtained, principally by the experiments of Hertz and of other investiga

tors who have extended the field of the Hertzian method of investigation. But it should be observed that the experiments of the pre-Hertzian epoch receive their full share of attention, as, for instance, the experiments of Rowland, Röntgen, and others.

The work will undoubtedly exert a very strong influence upon the future developments of the electromagnetic theory, and deserves, therefore, more than ordinary attention. This circumstance should, in the opinion of the reviewer, excuse the length of this review.

General Theory.-Poincaré's discussion divides itself naturally into two parts. In the first part an electromagnetic field with conductors at rest is considered. In the second part the discussion extends to electromagnetic fields with conductors in motion.

The Hertzian method of presentation is adopted in preference to the Maxwellian. Two distinct differences between these two methods should now be pointed out. The first difference is essential, and may be stated briefly as follows:

Hertz described Maxwell's electromagnetic theory as the theory which is contained in Maxwell's fundamental equations; he stated, however, very clearly that the suppression of all direct actions at a distance is a characteristic feature of this theory. But if it is not a sufficient hypothesis, and if no other hypotheses are clearly stated by Maxwell, then his deduction of the fundamental equations which form the heart and soul of his theory must necessarily lack in clearness and completeness. This is the difficulty This is the difficulty which Hertz discovered in Maxwell's systematic development of his own electromagnetic theory, and Hertz obviates this difficulty by starting from the equations themselves as given, proving their correctness by showing that they are in accordance with all our experience.

The second difference is formal only. It may be stated briefly as follows: Maxwell

considered the electrotonic state, discovered by Faraday, as of fundamental importance. The mathematical expression of this state, the vector potential, was considered by him as the fundamental function in his mathematical presentation of Faraday's view of electromagnetic phenomena. Hertz, just as Heaviside did some time before him, considered the vector potential as a rudimentary concept which should be carefully removed from the completed theory just as the scaffolding is removed from a finished building. In place of the vector potential Hertz substituted the electric and the magnetic force as the fundamental quantities. This enabled him to state the fundamental equations of Maxwell in a more symmetrical form than Maxwell did.

It seems that it is principally this second, the formal, difference which decides Poincaré in favor of the Hertzian method. But there is still considerable difference between the presentation of the electromagnetic theory given by Hertz and that which Poincaré gives in this book. For whereas Hertz proceeded from the symmetrical form of Maxwell's fundamental equations as given and by deducing from them and from several clearly defined assumptions the general experimentally established laws of electrical phenomena proved the correctness of these equations, Poincaré deduces them from the following experimentally established facts: 1. The energy of the electromagnetic field consists of two parts, one due to the action of the electric and the other to that of the magnetic forces. They are each homogeneous quadratic functions of the two fundamental quantities, that is of the electric and of the magnetic forces respectively. This experimental relation defines the units of the electric and of the magnetic force and also the physical constants of the medium, that is the specific inductive capacity and the magnetic permeability.

2. Having defined the meaning of mag

netic and of electric induction and of their fluxes in terms of the corresponding forces, Poincaré states then the fundamental law of electromagnetic induction in a closed conducting circuit as an experimental fact and deduces immediately the first group of the Maxwellian equations. This group is nothing more nor less than a symbolical statement that the law of electromagnetic induction is true for every circuit whether it be conducting or not.

3. Joule's law is stated as an experimental fact. In a homogeneous conductor the heat generated per unit volume and unit time at any point of the conductor is proportional to the square of the electric force at that point; the factor of proportionality is electrical conductivity by definition. Another quantity is then introduced which is defined as the product of the electrical force into the conductivity and the name of conduction current is given to it.

By means of these definitions, the principle of conservation of energy, and the first group of Maxwellian equations, the second group, in the form given by Hertz, is then deduced. This completes the Maxwellian electromagnetic theory for a homogeneous isotropic field in which both the medium and the conductors are at rest.

Poincaré loses no time in commenting upon the physical meaning of these equations, but proceeds rapidly to Poynting's theorem, which introduces one of the most important quantities in the wave-propagation of electromagnetic energy. It is the radiation vector, as Poincaré calls it. A brief remark, however, prepares the reader for the good things that are to come. A comparison of Maxwell's fundamental equations with those of Ampère shows them to be identical except for rapid electric oscillations, when the displacement currents (Poincaré does not mention this name, but only refers to a mathematical symbol) in

the dielectric cease to be negligibly small. For these no provision was made in Ampère's or any other of the older theories. Here then is the starting point of the radical departure of the Faraday-Maxwell view from that of the older theories. Hence the study of Hertzian oscillations takes us into a new region of electrical phenomena, a region entirely unexplored by the older theories, and first brought before our view by the discoveries and surmises of Faraday, by Maxwell's mathematical interpretation of these discoveries and surmises, and by Hertz's confirmation of Faraday and Maxwell.

Hertzian Oscillations. It is the study of these rapid oscillations which forms the subject of the rest of Poincaré's work under consideration.

Sir William Thomson's theory of the discharge of a Leyden jar forms a fitting introduction to this study. It states clearly the essential elements which should be considered in the study of electric oscillations. They are the period and the decrement. The relation of these to the self-induction, the electrostatic capacity, and the resistance of the circuit are given by this theory and it was verified by many experiments, especially those of Feddersen, who measured the period of these oscillations and also their decrement by a photographic method. But inasmuch as these oscillations were of a comparatively long period, 104 per second, they were not apt to furnish a test of the Faraday-Maxwell theory. The waves of the oscillations studied by Feddersen would have been 30 kilometers long and would, therefore, have escaped experimental detection.

Hertz was the first to produce very rapid oscillations, 108 per second; but since their period was too short to be measured directly, another method of testing the agreement between theory and experiment had to be devised. This was done by Hertz,

who measured the wave length (about 3 metres in the earliest experiments) of the waves produced by these rapid oscillations by means of the intensity of the spark in the spark-gap of a secondary circuit, the so-called resonator. The period was calculated by the Thomson formula and dividing the wave-length by the period gave the velocity of propagation, which, according to the Faraday-Maxwell theory, should be equal to that of light, and that, too, both in the immediate vicinity of the conductors and in the dielectric. A mere sketch of these experiments is given for the purpose of outlining the plan of the discussion to be carried out in the succeeding chapters of the book. Hertz's method of calculating the period of his oscillators is reproduced more or less faithfully and the various objections against it discussed.

Theory of Hertzian Oscillations.-This discussion paves the way gradually for the general theory of the Hertzian oscillator to be taken up in the next chapter. This theory can be described as the mathematical discussion of the following problem: Given a homogeneous dielectric extending indefinitely. This dielectric is acted upon by a steady electrical force applied at a conducductor, the oscillator. It is therefore electrically strained. Describe the process by means of which the dielectric returns to its neutral state when the initial electrical strain is suddenly released.

The discussion must necessarily start from Maxwell's fundamental equations. They are in the form given by Hertz, partial differential equations connecting the components of the electric and of the magnetic forces at any point in the dielectric. Hence, using the language of the mathematician, the solution of the above problem will consist in the integration of Maxwell's differential equations, which, translated into the language of the experimental physicist, means that the solution will consist in find

ing the resulting electrical wave, that is, its period, its decrement due to radiation and dissipation, and its direction and velocity of propagation. It is evident, therefore, both to the mathematician and to the physicist that the conditions at the boundary surfaces separating the dielectric from the conductor must first be settled. To these Poincaré devotes careful attention. A lucid demonstration is given of the theorems that in the case of rapid oscillations there will be a. Very slight penetration of the current into the conductor; b. A vanishing of the electric and the magnetic force in the interior of the conductor. c. Electric force normal and magnetic force tangential to the surface of the conductor,

etc.

Then follows a beautiful mathematical solution of the general problem mentioned above. It is this: The law of distribution of the conduction current on the oscillator being given the electric and magnetic force, and therefore the state of the wave, at any point in the dielectric and at any moment can be calculated by a simple differentiation of a quantity called the vector potential. This quantity is determined from the current distribution in a manner which is the same as that employed in the calculation of the electrostatic potential from the distribution of the electrical charge, but on the supposition that the force between the various points of the dielectric and the surface of the oscillator is propagated with the velocity of light. The value of this solution rests on the fact that the law of distribution of the conduction current can be closely estimated in some oscillators, as, for instance, in the case of Blondlot's oscillator consisting of a wire bent so as to form a rectangle in one of whose sides a small plate condenser is interposed. A special form of this vector potential applicable to oscillators whose surface is that of revolution is deduced and applied to Lodge's spherical oscillator,