cember, an Assembly of Notables to be elected by the people, which was designed to inaugurate the representative system, at least in form. The enthusiasm and independence with which the Fellaheen voted for their representatives revealed to the Government, and to the intriguing representatives of the numerous foreign interests and dynastic factions at Cairo, and their principals in the various capitals of Europe, that the liberal political ideas and nationalistic principles of the popular party had taken a deep root in the minds of the ancient race who once bore the torch of civilization, and who have since tilled their fertile valley under the whip of many masters.

The Khedive has interdicted the worldknown ceremony of the Dosseh. It was celebrated, every year, on the birthday of the Prophet. The accredited version concerning its origin is this: that an illustrious saint, wishing to convince the people of the sanctity of his mission, had the way from his house to the mosque covered with earthen vases; then, mounting his horse, he proceeded to the house of God without breaking one of the pieces. Those who witnessed the miraculous promenade were struck with wonder, and resolved that thereafter the sheik on horseback should pass over a carpet of human bodies. The sacred animal could only sanctify the faithful by the contact of its hoof. On the appointed day, every year, an immense crowd has been accustomed to assemble on the ground where the Dosseh is going to take place. English and other foreign tourists have been drawn frequently to the horrifying scene by curiosity. The frenzied devotees, often intoxicated with hasheesh, rush with low cries into the lane through which the horse is to pass, which has been kept clear by the police. They prostrate themselves in the way of the sheik as he sits on a splendid white horse, which half a dozen grooms are hardly able to hold. When the bit is let loose, he dashes across the animate pavement. After the sheik has passed, the fanatics, many of them crushed and wounded, disappear as if by enchantment.

OF.

ELECTRICITY, RECENT THEORIES James Clerk Maxwell enunciated the theory that light is an electrical vibration. The theoretical ground for this theory is the explanation which the two states of electric energy, static and kinetic, afford of the vibratory motion of light. Electricity, when passing through conductors or revolving within the poles of a magnet, is a kinetic force, and when dammed back by an insulator is a static force existing in a state of strain. Light is a form of energy which alternates between the kinetic and the static forms. Its rapid motion through a transparent medium is only comparable to the rate at which electricity travels along a conductor. When it is known that the velocity of light is numerically equal to the calculated rate of the transmission of an electromagnetic wave-disturbance, as has been the

oretically demonstrated by mathematicians, the connection between the two forms of energy, which are found also to touch each other at other points, and to interdepend in many respects, must naturally be supposed to be real and close. That the only known physical forces whose effects are transmitted through such wide media, and at such a high rate of motion, should possess precisely the same velocity constant proves that the phenomena can only be referred to the same source.

Professor Maxwell died before he was able to interpret the true relation between the two great groups of phenomena; but the certainty with which he established that they are the manifestations of one and the same force is the most valuable bequest left by that eminent theorist to the scientific world, which brings it to the threshold of a great advance in physical science. That light and electricity are related was first suspected by Faraday, who labored for years to establish his hypothesis. The only result which his many experiments yielded was the production of luminosity upon the surface of a dense kind of glass containing borate of lead, by exciting a powerful magnet, between whose poles a beam of polarized light had been projected upon the glass, and then interrupted. This experiment was first interpreted many years after by Maxwell and Sir William Thomson, and was the experimental basis of the Maxwellian theory. Many other transparent substances have been found to exhibit the same phenomenon in a less marked degree. A feeble luminosity has been discerned, even in common air, between the poles of a magnet similarly excited. Dr. Kerr has recently experimented in the same manner upon opaque bodies, and has shown that when light passes through a film of magnetized iron, thin enough to be translucent, its plane is rotated. The main fact which suggests an inseparable relation between light and electricity is the identical value of the velocity of light, which has often been measured, and of the constant, which expresses the rate at which a magnetic wave-disturbance would travel, which has been calculated from electric measurements. Maxwell's theory explains the fact noted above, that light transmitted through an active electric conductor must change its plane. It requires that insulators should be transparent, and conductors impervious to light. Even ebonite, the most opaque of electric insulators, has been shown by Graham Bell to be exceedingly transparent to some kinds of radiation. That the co-efficient of velocity of light in a transparent medium should depend upon its electric strain constant is a consequence of the theory. There are certain phenomena which, while showing an intimate connection between light and electricity, have not yet been explained in accordance with the theory. One of these is the remarkable effect of light in reducing the electric resistance of selenium, the light of a candle being sufficient to enhance

its conductive power fivefold. Another is the fact that light generates a current on striking the platinum electrode of a voltameter.

In further confirmation of Maxwell's electromagnetic theory of light, it has been proved by the experiments of Helmholtz, Fitzgerald, and others, that Fresnel's calculations of the intensity of light, reflected and refracted at the surface of meeting of transparent media, agree with this hypothesis in connection with the one assumed as the explanation of the laws of double refraction.

Professor Sylvanus P. Thompson, Jamin, and other eminent physicists, have formed a conception of electricity which resembles the old belief that it is a fluid substance. Experiments appear to show that in its relations to energy and matter it only acts as a transmitter of energy, and is not convertible into it. The quantity of electricity within a closed surface, it has been demonstrated, can not be increased or diminished without the entrance or outflow of electricity. It is concluded, then, that electricity is third entity, distinct from matter and from energy, the total quantity of which in the universe is conceived to be constant, as is the total quantity of matter or of energy. It resembles matter in that it requires the expenditure of energy to set it in motion, and, when its motion is arrested, its kinetic energy reappears in the form of heat or an equivalent form. The force with which a quantity of electricity acts upon another varies inversely as the square of the distance between them, as does the mutual attraction of bodies, but the effect is of the nature of repulsion instead of attraction. Electricity may be imagined to be a physical entity which does not possess mass, but yet possesses a quality corresponding to elasticity, and can be the recipient of energy in both the kinetic and the potential forms, and which tends to distribute itself equally throughout space, and exercises a definite pressure on those ultimate particles of matter which it does not penetrate. Under this supposition electricity would fulfill all the functions which are ascribed to the interstellar and intermolecular ether. The hypothesis of the imponderable ether of space may be abandoned in favor of the immaterial electricity which may be assumed to fill all space. Light would then be the vibrations of this elastic but imponderable medium. Heat, or the equivalent forms of energy, are the forms into which light vibrations of electricity change when the vibrations are arrested or absorbed, just as the vibration of matter, when arrested, changes into heat or its equivalents. But it is only the less refrangible rays-that is, the vibrations of greater wave-lengths-which nearly agree in period with the vibrations of molecules, and are convertible into calorific energy. The more rapid radiant vibrations, which produce actinic effects, do not expend their energy in thus intensifying molecular oscillations. Their electro-chemical action is explained by their

alternating displacements of the electricity of space in the surface molecules of a chemical compound which is decomposed by their action, at certain stages of which rapidly reversed electromotive action electrolysis occurs.

While the phenomena of radiant energy and the other problems which have led to the postulate of the hypothetical ether are satisfied by this theory of electricity, all electro-magnetic phenomena can be explained by the supposition of a constant tendency to the equalization of inequalities in the distribution of electricity. Electricity behaves like an incompressible fluid moving along stream-lines with the relative pressures and tensions between the various parts which would belong to such a fluid. A body which contains an excess of electricity or a deficiency as compared with neighboring bodies tends to transfer to them, or they to it, the quantity above or below the average charge. The two conditions of electrification known as positive or vitreous and negative or resinous consist, according to this hypothesis, of an excess or defect in the electricity contained in a body compared with the ordinary distribution. Which of these states is the surcharged condition has not been determined, though the weight of evidence indicates that it is that called negative and designated by the minus sign, the state of electrification which certainly tends more rapidly toward dissipation or discharge than does positive or vitreous electrification. The so-called minus, or, according to these conclusions, excessive or true plus electrification, is that possessed by the earth relatively to the surrounding space.

ELEMENTS, COMPOSITE NATURE OF THE. The spectroscopic studies of the materials of the sun, of the hotter and the cooler stars, and of the luminous nebulæ, have led to the belief that most of the chemical elements, as they are known to us, are compound bodies; and that they are all resolvable, though the means of dissociating their components are beyond human reach, into a very few simple gases, or perhaps into one single ultimate form of matter. In accordance with the nebular hypothesis, which is strengthened by the probabilities of this new theory, the many forms of matter are assumed to have been progressively developed from their ultimate constituents by the changes in physical conditions through which the universe has passed, the condensation and refrigeration of the matter of which cooler heavenly bodies, exemplified by our earth, are composed. The reasons for assuming the elementary nature of the so-called elements are, that they resist all efforts to decompose them, and secondarily that they enter in definite proportions into chemical compounds. The property of chemical stability is manifested in many degrees. Many compound substances combine as radicles and show a close resemblance to the elements in their behavior in certain relations. The building up of homogeneous substances from materials which are themselves complex com

pounds formed from the union of other conpounds, is the usual manner in which the minerals of the earth's crust were formed. The metamorphic combinations through which the chemical constituents of organic substances pass are still more complex. Since the many thousand substances which are found on the earth have been resolved into a limited number of bodies, it may be expected that improved experimental methods will discover the compound character of some of them, and that perhaps whole groups of the present elements will give way to analytical experiments, as did the alkalies and earths which were regarded as primary substances at the beginning of this century. Nor, when the limited means which we possess for overcoming the cohesive force of molecules are considered, can it be taken for granted that any of the supposed elements possess the atomic constitution and physical properties of the substances which composed the solar universe when the solid bodies of the planets and the liquid mass of the sun were dissolved into one fiery, gaseous flux, whose molecular particles developed a heat in their collisions far beyond that of the sun.

Recent scientific speculation conjectures a cold nebular condition anterior to the luminous nebular period. It is supposed that, among the phases through which the stellar systems pass, may be one in which the gaseous matter is dispersed so widely in space that the flying molecules do not impinge upon each other with sufficient frequency to produce the manifestations of heat and light. In that condition the division of matter may have been finer, and its constitution more homogeneous, than when it was drawn together, in accordance with the most universal law which science has established that of the mutual attraction of bodies -into closer contact. The elements whose existence seems to be best established in the hotter stars and the nebula are the primary gases of the earth's surface-hydrogen, oxygen, nitrogen. Hydrogen seems to be present in all luminous bodies which have been examined with the spectroscope, where it occupies a position in the outer atmosphere. Nitrogen is the only other terrestrial substance whose presence in the nebulæ is ascertained. It has not been detected in the solar spectrum, but this is probably owing to the difficulty of determining the composition of a fused mass enveloped in an atmosphere of incandescent gases. As it forms so large a proportion of the earth's atmosphere, it must be inferred from the nebular hypothesis that it exists in the central body, which constitutes nearly of the total mass of the solar system, unless it also be supposed to be one of the substances which have come into being during the process of cooling. Its presence in the incandescent nebulæ, its gaseous nature, and its probable simple molecular constitution, indicated by its light atomic weight, render this an unlikely supposition. The recent discovery of oxygen in the sun illustrates the

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difficulty of reading the solar spectrum, and strengthens the expectation of finding nitrogen and perhaps numerous other unobserved bodies in the sun.

The nebular spectra seem to be simpler than those of any of the solar bodies. Besides the two gases mentioned, the only other substance observed which projects a well-defined line is an unknown element whose spectrum resembles that of barium; but the proximity of its line to the barium line is supposed to be purely accidental. This, like the two known substances which have been identified in the nebulæ, may be presumed to be a gas of light atomic weight, which preserves the gaseous form at exceedingly low temperatures. In the formation of the solar system from a diffused nebulous mass, the kinetic theory would require that the gaseous materials should rise in temperature as they are brought into closer and closer compass before condensing into liquid forms. The hypothesis is that the unknown substance which has been discovered in the nebulæ, or substances if there are more such, was also represented in the solar system when in the nebular state; and that, when the gases were compressed more and more closely around. the nuclear mass in obedience to the principle of gravitation, the rise of temperature which attended the process transformed these substances, while the other gases remained stable.

The theory was thus stated by Lester F. Ward in a meeting of the Philosophical Society of Washington: "Prior to the stage in the history of a nebula at which the degree of molar aggregation is sufficient to occasion a great amount of friction among the particles, the temperature of the primary molecular aggregates must be nearly that of space, and it can rise only as increase of density and molar motion increases that friction, and converts material motion into ethereal vibration. Neb ulæ must therefore possess a long history, of which neither the telescope nor the spectroscope can furnish any record-the pre-luminous period-in which, of course, no gases can exist except those, like hydrogen and nitrogen, which maintain their gaseous form under extremely low temperature. And it may be supposed that during this period other gases may exist associated with these, which, however, unlike them, are unable to sustain the successively higher and higher temperatures which the nebula acquires in its process of condensation and organization into a system, and at certain stages of this process are dissociated and resolved into aggregates of a different constitution, suited to these temperatures. Some of the latter new aggregates would naturally assume the liquid and solid forms at temperatures still high as compared with those to which we are accustomed, and constitute in the cooled-off crust of the planets the various metals and metalloids. In this manner we should have no difficulty in accounting for the

existence of all the elements found on the earth, even if it were positively known that only the lighter gases were present in the parent nebulæ." This theory accounts for the presence in the nebula of a substance not present in the solar system, which is assumed to have once passed through the same physical condition, associated with other substances which are indubitably abundant in the sun and its planets, and for many substances present in the earth, some of which have been detected in the sun and stars, and numerous others of which are probably contained in them, of which no traces are found in the nebular spectra. It also explains how these substances could have been derived from the nebular mass when their existence in a volatile state would necessitate a temperature far higher than can be supposed to have ever prevailed throughout the original nebula. Those elements which have the highest melting and volatilizing points are precisely those which have the greatest atomic weight, and are therefore the most likely to be of composite nature; while those which have the lowest combining numbers, and are therefore more likely to be simple substances, are those which have as a rule extremely low condensing points. Carbon, which, with an atomic weight of 12, assumes solid forms at ordinary temperatures, and mercury, which can be vaporized at a low temperature, while its combining number is in the new system 200, are the only exceptions to this rule. A law in experimental chemistry is, that the increase of mass in the formation of compound molecules is attended with a decrease of stability. Many of the metallic and metalloidal elements combine in larger molecular masses than are possessed by many compound substances. If they are the products of the metamorphosis of lost elementary substances at a time when the heat of the nascent solar system was greatest, they can not be expected to be resolved into their primary constituents by human means. Those of them which are found in the sun may be suspected to belong to this category. Those which are found only in the earth may be compounds formed at a lower temperature. Many molecules of hydrogen, or of nitrogen, carbon, or oxygen, might be contained in a molecule of gold, of platinum, or of lead.

It is consonant with the atomic theory to consider the stability of the elements as only relative. Even the molecule of hydrogen, which is taken as the standard and unit of molecular measurement, may be a superior form of atomic arrangement. There may be substances with minuter and simpler molecules which can not be appreciated by the senses, and do not respond to the physical law of attraction to a measurable extent. The imponderable interstellar ether is matter which is not visibly subject to the influence of gravitation. Possibly there exist atomic aggregates of still lower order. All known substances may have been evolved from antecedent forms

of matter. The process of evolution is seen to go on in all the known forms of matter, and the evolution of matter with an altered molecular constitution would naturally be supposed to have attended the other physical changes in the history of nebula and their consolidation into planetary systems. The anomalous phenomena of ozone and antozone bring into question the absolute stability of the presumably simplest and most elementary substances. The unknown substance which gives out the green ray in the solar spectrum has been conjectured to be of simpler constitution than any of the terrestrial elements.

In the various homologous series of hydrocarbons the boiling point of the compounds rises, and their specific gravity increases, with their molecular complexity or increase in molecular weight. The broadest and most securely established general law in chemistry is that substances with the lowest atomicity have the lowest melting-points and the simplest spectra, and that both these functions are in a general way proportional to the combining number of a substance. The hypothesis of variable molecular groupings under different conditions within the so-called elements explains many facts which are now anomalous. It accounts for the irregular vapor densities of some substances. The phenomenon of allotropism exhibited by various metalloids, which is most marked with those which have not been found in the sun, is thus explained. The allotropic substances exhibit complex spectra, and their spectra are often different for the different allotropic states. In passing from one allotropic condition to another, energy is invariably evolved or absorbed, which can only be accounted for on the supposition that it controls changes in the molecular disposition of the atoms. The phenomena of polymerism in organic substances can only be explained by the theory of the variability of constitution of substances known to us as primary. The spectrum of potassium varies exceedingly at different temperatures, and the spectra present a marked analogy to those of hydrocarbons evolved during fractional distillation.

The coincidence of some of the bright lines in the spectra belonging to different metals was first noticed by Kirchhoff. The brightest stars give only a few prominent lines, and these are the same as those which show bright in the spectrum of the solar disk. In Sirius there are only half a dozen well-marked lines. The cold stars, which give a feeble and reddish light, have fluted spectra instead of lines. The fluted spectrum of any substance gives place at higher temperatures to the line-spectrum characteristic of the same substance; and when the elevation of temperature is gradual, the bright lines of an element appear in the same way in which the lines of the constituents of a compound appear, instead of the spectrum of the compound when the latter is broken up. In the laborious spectrum

analyses conducted by Lockyer on the plan of comparing superimposed photographic images, and of eliminating impurities from the spectra studied, it was found in the case of iron, for example, that the fact of a line coinciding with one of some different substance was not an exception but the rule. In the region between 39 and 40, where scarcely any iron lines had before been observed, and only 5 lines in the solar spectrum, the photographic process revealed nearly 300 solar lines and 62 lines of iron, of which latter 44 corresponded in position to lines of other metals.

Lockyer's analytical study of the spectra of different parts of the sun proves that the lines of each substance are fewer and the spectrum much simpler in the hotter than in the cooler regions. The flames or prominences are taken to be outbursts from the interior, and to show the highest temperature that can be examined. The spots possess an intermediate degree of temperature between the storm-flames and the regions which are free from either spots or storms, and which are supposed to be the coolest. The lines of iron, for example, most prominent in the flames are very different from those which show thickest in the spots, and are much fewer. The spectrum of the spots, while varying greatly in the lines seen, is generally simpler than that even which is obtained in the electric spark. The spectra of the spots are not only much simpler than the sun's spectrum as a whole, and the flame-spectra than the spot-spectra, but totally different lines are projected at the transcendental temperatures of the flames. The cause of the difference in the lines is found in the changes observed in the refrangibility of lines due to variations of velocity in the movement of various solar vapors. Tacchini, when watching the two iron lines 4922-5 and 5016-5 in a solar storin, suddenly saw them both disappear, while two other entirely new lines made their appearance in their neighborhood and remained for several months. It is a natural inference that at the unusually intense temperature which then existed iron is decomposed. The lines of iron which are thickened in the spots, those which show bright in the flames, and those which are regarded as the basic lines of the metal, are almost without exception the same lines.

The latest theories of spectroscopy, according to which the line, the fluted, and the continuous spectra form a gradation whose stages indicate the greater or less aggregation of atoms in the molecules, are confirmed by proofs of various kinds. The three types of spectra are not separated by distinct boundaries, but merge into each other and form a continuously progressive series. Compound bodies never give a line-spectrum. Their spectra are either fluted bands or continuous. Some elementary bodies give continuous and fluted spectra at lower temperatures, and at high temperatures line-spectra. Their low-temperature bands can be determined by their absorption spectra,

which are the converse of their proper spectra, the rays absorbed by a body from transmitted light being the same which it emits when incandescent. The theoretical inference is, that the change from one kind of spectrum to another is due to a change in the mass of the individual molecules, their splitting up into smaller molecules or their concretion into larger ones. The absorption spectra of the vapors of iodine, bromine, and the metals silver, potassium, sodium, etc., show fluted bands. The spectra projected by the same substances when rendered luminous by a powerful electric spark are simple lines. The results of Victor Meyer and others, who have recently effected the dissociation of the halogens, and proved that iodine and bromine molecules do separate into smaller atomic aggregates at high temperatures, furnish an experimental confirmation of the theory that the different types of spectra show the relative complexity of the molecules. Sulphur-molecules are known by their chemical behavior to divide into three at the temperature of 1,000° centigrade; and in this condition they project a fluted spectrum instead of the ordinary continuous spectrum of sulphur.

ENGINEERING. On the American Continent and that of Europe some of the largest engineering works ever attempted are in progress, or are about to be begun. The Channel Tunnel from France to England, underneath the Straits of Dover, is the most formidable enterprise; and although large sums have been expended in the preliminary works, and the feasibility of the scheme is reasonably demonstrated, still the promoters may yet reconsider the probabilities of sufficient returns, and the project be again put off into the indefinite future, after a considerable portion of the work has been accomplished. The Arlberg Tunnel through the Alps is another of the gigantic bores through the heart of a mass of mountains which modern engineering makes possible and modern international commerce and intercourse render remunerative. As the mountainbarriers between Western Europe and Italy have been thus leveled, and as those which divide Switzerland and Austria will be leveled by this new tunnel, so it is proposed to pierce the Pyrenees and connect France and Spain by a railroad. The projected canal through the Isthmus of Corinth, a revival of a scheme which occupied the thoughts of engineers and rulers in ancient Greece, is not yet actually commenced, but is one of the newer projects conceived under conditions favorable to success. General Türr, the Hungarian patriot, has received a concession from the Greek Government for the execution of the design, and French engineers will be engaged in the work. The cutting of canals, broad and deep enough to float the largest iron steamships, through every narrow neck of land where such works will materially shorten the main ocean trade routes, is rendered desirable and profitable by