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faring people had extended their journeys, if not their colonies, to that comparatively remote quarter. This interesting relic has been ably worked up by Professor Pauli, who may be said to be at the head of living Etruscologists.

About the time that the Etruscans settled in Italy, a people of closely similar name, the Tursha, appear in Egyptian history as bold invaders and daring warriors. They are mentioned in the inscriptions of Meneptah II. and Ramses III, and by most writers are considered of the same stock as the Turseni, Tyrrheni, Tursci, or Etruscans. They were allies with the Libyans, and entered the Fayoom with these in the Ramesside period from the Libyan territory to the west. Professor Krall accepts this identification, but adds the cautious and just remark, that we have no positive knowledge of the language spoken by these Libyan neighbors of Egypt at the time mentioned. Of course, if they were the Tursha, and these were the Etruscans, we should see our way much more clearly.

CREMATION OF CHOLERA CORPSES.

BY ALBERT S. ASHMEAD, M.D., NEW YORK.

LET me add a few words to the article of mine, entitled "Cremation of Cholera Corpses." which you published Sept. 2.

I said in the New York Tribune, Sept. 22,' that religious prejudices should not interfere with the enforced cremation of cholera corpses.

This is what Professor Stillé writes to me about the subject: "In regard to cremation, I have no doubt of its being the proper way to dispose of the dead, and that it originated, as all sanitary laws did, not in divine command, but in human wisdom derived from experience.

"If the Egyptians had possessed fuel, I have no doubt they would have burned their dead, and that the Jews would have followed them in this as in most of their sanitary laws, e.g., circumcision, unclean meats, etc. Of course, with Greeks, Romans, and Christians the doctrine of the resurrection of the dead (most distinct, of course, in the last) led to the preservation of inhumation.

"There are many persons even now who believe in the literal resurrection of the actual body, albeit they are at a loss to give a reason for this popular belief. After all, I doubt if cremation of the dead will become usual. Superstition will hinder it among the ignorant, and tenderness among the refined."

There are in the history of the treatment of infectious and contagious diseases three periods.

1. There was a barbarous period when every, let us say, leper, was considered as outside of the pale of humanity, without any right to the sympathy of his fellow-men, only not killed because there is a law of the Decalogue against killing. The leper, as we

1 TO THE EDITOR OF THE Tribune: No more salutary measures have ever been taken against the spreading of cholera than the burning of the cholera corpses at Swinburne Island. It is evident that as long as the bacillus has not been entirely destroyed it will live to fight again. However deep it may be buried, at some time it will reach the surface again, get mixed with the water we drink, and cultivate itself in the human body. Why then should a measure so necessary for our safety be limited to such uncared for bodies as those who are found on vessels stationed at quarantine in the bay? The same danger threatens us from the bodies of those who die in the city. There is no use in saying that they will be buried in metallic coffins. Metal may keep the enemy in harmless seclusion for a longer time, but not forever. Moreover, metal renders the process of putrefaction slower, and keeps the bacillus which feeds on the corpse longer alive. There is probably no difference in regard to the danger arising from buried germs, whether the corpse be buried in wood or in iron. Therefore, it is evidently a duty of a board of health which cares truly for the public welfare to enforce cremation of all cholera corpses in the city as well as on the ships. Religious prejudices can really not interfere with that; the body reduced to ashes can resuscitate as well as the body burled, for it is clear that any corpse long before the general resurrection of the dead will be reduced to a condition entirely similar to that which cremation brings about. Or, if it is only the routine of the ignorant that stands in the way, it is the right and the duty of the educated and learned to impose by law and by force what is necessary to the welfare of the whole community. If we must bury our corpses, let us at least bury them in the most rational way possible. Wood decays, iron rusts or bursts, but earthenware jars are absolutely impermeable, and even indestructible. These have been used for more than a thousand years by the royalty and higher classes of Japan, and as we are, just now, teaching the Japanese so much, it is only fair that, when they are entirely in the right, and have given a great deal of thought to the matter, they should teach us something, too. They put vermillion with the cadaver; we might use bichloride of mercury.

have chosen him as the representative of this class of wretches, was condemned to solitude, absolute isolation; if he came by chance within hail of any fortunate healthy brother or sister. he had to ring a bell which he was obliged by law to always carry about him, in order to let them know that somebody was approaching who had no right to approach his fellow-being, and whose presence was an involuntary menace of death! These men were utter outcasts, enemies to be kept off as wild beasts are, completely neglected; when they were found dead, their carcasses were buried that was the only duty which society performed in their behalf.

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2. The second may be called the Medieval-Christian period. Then something was done for them, in fact everything which those dark centuries knew how to do. Misericordias were formed, societies of St. Lazarus, etc. Asylums, hospitals were established. Of course, the greatest service the men of that time thought that they could render their unfortunate brethren was - prayers, the ceremonies of religion. For the etiology was - visitation of God, punished sin, etc. In a time of epidemic the sanitary measures consisted in holy processions with banners flying, crosses, candles, holy-water; also relics, such as the seamless coat of Treves, a thousand ugly images of the Virgin meeting the traveller at every step. Have not we seen here in New York thousands kissing a bone?

3. The third period is the age of reason, the sanitary period, when superstition, ignorance, and fanaticism must be kept in check, brought to bay, utterly ignored, in every question of public health. We know now what we have to do; there is no excuse for not doing it. If, with the knowledge we have, we pander to the ridiculous pretentions of those who stupidly try to keep up the regime of the Middle Ages, we are simply criminal.

SOME POINTS IN CHRONOLOGY.

BY R. W. MCFARLAND.

THE difficulties met with in chronology are best understood by those who have given most attention to the subject. In ancient times each nation was a law unto itself, touching the method of counting time or registering great events.

The Egyptians, several thousand years B.C., knew that the year was very nearly 365 days. They, however, dropped the fraction and retained only the whole number. It is said on good authority that this error of one-quarter was allowed to remain, so that by losing one-quarter of a day each year the seasons would slide forward around the whole heavens in 1461 years. By this slow motion of the seasons through the year, the festivals of the gods in like manner would be celebrated in all the seasons, to the end that all the gods should be honored equally and in exactly the same way.

The Roman calendar was amended by Julius Cæsar, 46 years B.C., with and by the aid of an Alexandrian astronomer. We use what is substantially the Roman calendar. It would not be proper in this place to enter into an explanation of the minutia of many points in doubt or in controversy. The immediate cause of Cæsar's reform was the vicious habit of the pontiffs in calling out or proclaiming the beginning of the months in such a way as to serve political ends or emergencies. Of course most people who are conversant with the derivation of words know that the word "calendar" is from the Latin calare, to call, or to proclaim. As a consequence of the reformation by Cæsar, the year 46 B.C. was made to consist of 445 days, and is sometimes known as the year of confusion. The year 45 B.C., the first of the reformed calendar, coincided in the main with the year 708 of the city of Rome. This is the Julian calendar which was followed in general by the Latin Empire, and was naturally adopted by the various nations after their incorporation into the Roman dominions. The old Egyptian year of 365 days was merely transferred to a more northern region, and into a far wider territory. It was not till long after the conversion of the Emperor Constantine to Christianity in the year 320, viz., in the early part of the sixth century, that the proposition was made to count the assumed date of

the birth of Christ, as the beginning of the era — - the one now in common use by all Christian nations.

For ecclesiastical purposes the early Christians adopted in part, at least, the Jewish calendar, especially for the feast of Easter, the counterpart of the Jewish passover the 14th of Abib, the first month of the year. "In the fourteenth day of the first month at even is the Lord's passover."- Leviticus xxiii., 5. But the fourteenth day did not generally fall on the Sabbath. Some churches celebrated Easter on the fourteenth, and some on the following Sunday. This caused some contention, and easily grew into a matter of supreme importance for the church. In the year 325 of our era, the council which convened at the city of Nicæa, beyond Constantinople, decided that the feast of Easter should be celebrated on Sunday, and that it should be the Sunday following the day of the full moon, which should occur on, or next after, the 21st of March. The intention was to fix the time of Easter as nearly as a movable feast could be fixed. The Jewish year was luni-solar- twelve months for one year, thirteen for the next.

Early in the fifteenth century the ecclesiastics noticed that the equinox was slipping away from the 21st of March. The question was discussed more or less for nearly two hundred years before final action was taken. In 1582 the equinox occurred on the 11th of March instead of the 21st, as at the time of the Council of Nicæa, in 325. Pope Gregory XIII., with the aid of able coadjutors, reformed the Julian calendar. His object was to prevent in the future such diversity of days in celebrating the same feast. The change made by Gregory consisted chiefly of two points: 1, The skipping of ten days in order to bring the equinox back to the 21st of March; and 2, To arrange an order of leap years which should prevent a like divergence thereafter. The omitted days were the ten following the 4th of October, 1582. The day which in the ordinary course of events would have been the 5th was reckoned as the 15th of October, new style. The Julian calendar, with every fourth year a leap year, is old style. Gregory excepted the centesimal years, decreeing that only those which are divisible by 400 should be called leap years. The year 1600 being divisible by 4 and by 400 was a leap year in both styles. Wherefore the difference between the two styles continued ten days for a century after 1600, viz., till midnight of the 28th of February, 1700. In new style, 1700, not being divisible by 400, was a common year, and the day following the 28th of February was March 1. But in countries which still adhered to the old style, 1700, being divisible by 4, was a leap year; so the day following the 28th of February was the 29th. Here there began a difference of eleven days between the styles. A like case occurred on the 28th of February in 1800, and the difference became twelve days, and will so continue till February 28, 1900; after which for 200 years the difference will be thirteen days. Russia still adheres to the Julian calendar, and the 12th of October, 1892, in that country will be the 24th in this.

The change of style by Gregory looked solely to the future, in order to prevent unseemly changes in the time or date of church festivals. It did not disturb the past at all, and was not intended to do so. As a proof of this, it may be stated that no date previous to October 4, 1582, old style, was ever changed by Gregory or any of his successors, or by any body of learned men, or of unlearned men; that no writer of history or of chronology in any European nation has changed or attempted to change such dates from old to new style. The discovery of America was on Friday, October 12, 1492, old style. It is so written "always and everywhere and by all."

It was reserved for the American Congress of 1892, instigated by a committee of some ill-informed society, to depart from established and uniform custom, and to declare that the 21st of October, 1892, should be celebrated as the 400th anniversary of the discovery. It is a "consummation devoutly to be wished" that this hasty and ill-advised action of Congress may die a speedy death, and that after this year it may never again be thought of or regarded in any way.

The present Pope, in his announcement concerning" Columbus Day," utterly ignores this act of Congress. He says, according to current reports in the daily press, that on the twelfth of Octo

ber or on the following Sunday (the 16th) appropriate services will be had in commemoration of the great discovery. It is to hoped that some friend will call his attention to the unadulterated wisdom displayed on this side of the Atlantic, regardless of the "effete monarchies " of Europe.

England adhered to the Julian calendar till about the first of September, 1752. To be specific, the order of Parliament was that the day following the second of September of that year should be called the fourteenth, and that the year which previously began on March 25 should begin on January 1, 1752, to conform to the Gregorian calendar. Macaulay, Hume, Robertson, and all other historians who have written in the English language of events in English history, give the dates in old style up to the year 1752.

In the colonies on this continent, planted by the French, Dutch, Spanish, and English, each followed the custom of the mother country, some using old and some new style. After the Revolutionary War Ramsay's Life of Washington was written. In it Washington's birth is given in old style only, viz., February 11, 1731,-conforming to the English custom of leaving unchanged all dates before the change of style. But "necessity knows no law;" so the conflicting dates of the various colonies were assimilated by all being made new style, for events occurring on this continent.

Such is a brief account of some points in chronology, which account may be of interest to many and may stir up some to a more careful study of a much neglected subject. Oxford, Ohio, September, 1892.

SOME THOUGHTS ON THE PHYLOGENY OF THE MOLE

CRICKET.

BY E. W. DORAN, PH.D., COLLEGE PARK, MD.

I HAVE recently been able to work out to some extent the lifehistory of the Northern Mole Cricket, Gryllotalpa borealis. The various stages of the insect seem not to have been studied extensively, or described, before. I have made some observations of interest which I have not seen recorded elsewhere, and which seem to indicate the course of development in this species. I am led to believe that formerly the insect lived upon the surface of the ground, or in natural hiding places, very much like our common field cricket, instead of burrowing into the earth, and passing all its existence under ground.

My first reason for supposing a change of habit has taken place is based upon the fact that the larva, before the first moult, is able to jump like the field and house-cricket. (Larvæ but little over a fourth of an inch long were seen to jump five or six inches in the breeding-jars.) They are otherwise very active and brisk in their movements. After this stage the insect cannot jump at all, and is very clumsy. It can run rather rapidly backward or forward in its burrow, or upon a level surface, but has very awkward movements upon an uneven surface. The abdomen is long and heavy, especially in the pupa and imago.

Now this would indicate that originally the mole cricket had the power of jumping like most other orthoptera, and all other Gryllido, I think, and lived upon the surface of the ground, perhaps hiding in crevices, or under rubbish, like the common cricket. But having taken to the burrowing habit, and no longer finding the necessity for exercising its power of leaping, it gradually lost that power, until it appears only in the early part of the larval stage.

My second reason for this conclusion is based upon the habit the mole cricket has of defending itself in the burrow by ejecting posteriorly a creamy, viscid substance in large quantities, which rapidly thickens after exposure to the atmosphere. This fluid seems also to have peculiar chemical properties. In this way it is able to protect itself from almost any foe which may attack it from behind, and it tights viciously if attacked in front. Now, the larva before the first moult does not have the power of ejecting this substance, and this would possibly indicate that in a previous stage of its development the mature insect was not so armed, for the young larva certainly needs protection as much as

in later life. This method of defence would not be so effectual upon the surface of the ground where its enemy could attack it from any source instead of directly behind or before, because with its unwieldy body it would not be able to eject the substance In any desired direction suddenly. This, then, appears to be a habit acquired by the insect since it has taken to its underground life; for it is hardly probable that it would be provided both with the habit of making long leaps to escape from its enemies, and at the same time to eject in large quantities this protective fluid. There are some rather serious objections to this theory of changed conditions and habits. First may be mentioned the unusual development of the tarsus, fitting it for its underground life and burrowing propensities; but it is not unreasonable to suppose that the front legs were developed gradually in conformity with its changing habits. And it is perhaps true that if the insect lived upon the ground, it occasionally burrowed for roots, or for shelter, and originally had an unusual development of the tarsus. Its carnivorous habits may have been acquired in consesequence of its frequent contact with earth-worms, when other food was scarce, as there are many other insects which normally feed upon vegetable food, that will resort to animal food, devouring even their own kind, as in the mole cricket, when pressed by hunger.

Second, an observation made by Westwood and others in Europe upon G. vulgaris would seem to weaken my argument regarding the development of the insect. It is stated that the larvæ of the European species, before the first moult, live together in one burrow, with the mother cricket, but scatter after this moult. I have seen the very young larvæ of our species only in confinement, and cannot say whether in the natural state they would scatter before this time or not. They run about in the breeding-cage more before the first moult than afterward. However, I think it probable that the mother cricket feeds the young, at this early stage, as she exercises great solicitude for them apparently, in other matters, or in time of danger. I have several times seen the mother take the young in her mouth when disturbed, as a cat does her kitten, and carry them to places of safety. She will also carry her eggs to a new burrow when they have been discovered, as I have several times observed. Hence it seems probable the young larvæ live together under the protection of the mother cricket, and would have but little need of a protective ejection. But the jumping habit which is chiefly useful in escaping from their enemies, being confined only to the early larval stage, presents a stronger argument for changed conditions. I may say, however, that neither of these are presented as conclusive arguments but rather mere suppositions or suggestions, to be followed up by other observations.

THE SCIENCE OF SMELLING.

BY PROF. DE VOLSON WOOD, STEVENS INSTITUTE, HOBOKEN, N. J. THE greater part of the science of seeing is contained in the science of optics, and this is founded upon the theory of undulations of the ether and the way in which they are modified by the media through which they pass. The form of the surface, whether plane or curved, as well as the density of the medium produces marked effects.

Similarly, the greater part of the science of hearing is contained in the science of acoustics, and this also treats of undulations, or waves propagated in air or other gases. It is not believed in either case that solid particles pass from a source to the sensitive nerves to produce the particular sensation.

Why should there not be a science of smelling? The principal part of such a science would consist of an investigation of the mechanical properties of odors, and might briefly be called "Odorology." Is it not highly probable that odors are also propagated by undulations of an ether? And yet we are familiar with the statements made by writers, such as “A grain of musk will keep a room scented for many years. During the whole of the time it must be slowly evaporating, giving out its particles to the currents of air to be wafted presently out of doors; yet in all this time the musk seems to lose but little of its weight." acute sense of smell of the dog is well known; for he can detect

"The

the track of his master long after the tracks have been made, which shows that some slight characteristic matter is left at each footfall."

Those who thus speak impart the idea that odor is material. I prefer to think of it as a property of matter, which produces its own peculiar undulations; and that the sensation of odor is produced by these undulations in the olfactories. Musk retains this property for a very long time, while some bodies lose it rapidly. The man may leave some characteristic matter on the ground at each footstep, but it is not necessary that particles of that matter shall pass from the ground into the nose of the dog in order that he may track his master. It is only necessary that that matter shall possess the property of sending forth certain undulations. Indeed, it is not difficult to conceive that the ground itself has imparted to it the property of sending forth the desired undulations.

These facts being assumed, investigations might be made to determine the velocity with which odors are propagated, and whether they are subject to reflection, refraction, and interference, and other properties common to sound and light; also whether the different odors are due to different wave-lengths, and if the strength and intensity of the odor is due to the amplitude of the wave, as in light and sound. The physiological qualities of the olfactories by which they enable one to detect odors of different qualities and intensities furnish a field for the most delicate and refined investigation.

NOTES AND NEWS.

PERSONS who are very susceptible to the effects of gnat-bites state that the irritation seems to return on the third day, and in those who have exceptionally sensitive skins again on the sixth day. Thus the effects of gnat-bites, or rather of the poison which they instil into our blood, have a certain analogy with the symptoms of intermittent fever. This need, perhaps, scarcely surprise us if we recollect from what materials the juices of the gnat have been elaborated.

Herbert M. Thompson's "The Theory of Wages and its Application to the Eight-Hours Question," published by Macmillan & Co., is a timely contribution to the discussion of this vital question of the present industrial crisis.

-Lovers of birds and flowers will delight in Miss Yonge's new book announced by Macmillan & Co. Under the title of "An Old Woman's Outlook" she describes out-door life in England as she has watched it for so many years. The chapters are so arranged that each shall cover its special month.

"Round London, Down-East, and Up-West" is the self-explaining title of a new book by Montagu Williams, barrister, author of "Leaves From a Life," etc. It will be issued by the Macmillans.

- D. Appleton & Co. will shortly add to their list of Good Books for Young Readers "Along the Florida Reef," by C. F. Holder, which is a story of camping and fishing adventures in company with a naturalist in Florida. The author combines entertainment and instruction, and his book is filled with illustrations which will be prized by every young reader who has ever visited the seashore, or cares for information regarding fishes, shells, and the various forms of marine life. The same firm will publish immediately "The Story of Columbus," by Elizabeth Eggleston Seelye, edited by Dr. Edward Eggleston, with nearly a hundred illustrations by Allegra Eggleston. This book is the result of extensive investigations which have been carefully verified by Dr. Eggleston. While the book contains all the results of modern inquiry offered in the bulkiest biographies, the story is here condensed and the material selected with a view to an always interesting narrative. To a considerable extent the plan of both text and illustrations is like that of Eggleston's "Household History of the United States." "The Story of Columbus will be the first volume in a series to be called Delights of History, which will be prepared by the same author, artist, and editor.

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To any contributor, on request in advance, one hundred copies of the issue containing his article will be sent without charge. More copies will be supplied at about cost, also if ordered in advance. Reprints are not supplied, as for obvious reasons we desire to circulate as many copies of Science as possible. Authors are, however, at perfect liberty to have their articles reprinted elsewhere. For illustrations, drawings in black and white suitable for photoengraving should be supplied by the contributor. Rejected manuscripts will be returned to the authors only when the requisite amount of postage accompanies the manuscript. Whatever is intended for insertion must be authenticated by the name and address of the writer; not necessarily for publication, but as a guaranty of good faith. We do not hold ourselves responsible for any view or opinions expressed in the communications of our correspondents. Attention is called to the "Wants" column. It is invaluable to those who use it in soliciting information or seeking new positions. The name and address of applicants should be given in full, so that answers will go direct to them. The "Exchange" column is likewise open.

VON DEN LICHTSTRAHLEN KLEINSTER WELLEN

LÄNGE.

VON VICTOR SCHUMANN IN LEIPZIG.

LANGE Zeit galten die Wellenlängen zweier Linien des Aluminiumspectrums als die kleinsten. Nach den Messungen A. Cornus betrugen die Längen dieser Linien in Angströmeinheiten (1 Angströmeinheit = 0.0000001 Millimeter) ausgedrückt, 1860 und 1852 AE. Für beide Linien ist, wie schon für die ganze Spectralregion des Ultravioletten, das menschliche Auge vollständig unempfindlich. Nur sehr wenigen ist es vergönnt, das Ultraviolett durchs Ocular eines hinreichend lichtdurchlässigen Spectralapparats ebenso deutlich wahrnehmen zu können, wie die minderabgelenkte Region des sichtbaren Spectrums, das, wie allgemein bekannt, von jedem gesunden Auge vollkräftig empfunden wird. Das ultraviolette Licht lässt sich nur auf einen Umwege sichtbar machen; entweder projicirt man es auf einen fluorescirenden Schirm oder fixirt es mit Hilfe der Photographie auf einer lichtempfindlichen Platte.

Das Fluorescenzspectrum kann man direct oder durch eine Lupe betrachten; in beiden Fällen lässt es aber an Klarheit und Schärfe viel zu wünschen übrig. In früheren Jahren, wo die photographische Platte dem nassen Verfahren angehörte und die moderne Trockenplatte noch nicht bekannt war, hat man sich vielfach des Fluorescenzspectrums bedient, wenn es sich um Versuche mit ultravioletten Strahlen handelte. Gegenwärtig, wo die Bromsilbergelatineplatte der photographischen Beobachtung so ausserordentliche Vortheile gawährt, denkt wohl niemand mehr an die Verwendung des unvollkommenen Fluorescenzspectrums.

Die photographische Beobachtung hat die oculare aus dem Ultravioletten vollständig verdrängt. Wer beide Methoden geübt hat, wird mir beipflichten, wenn ich sage: das Fluorescenzspectrum ist viel zu roh, als dass es der exacten Spectroskopie der Gegenwart noch gewachsen wäre.

Die moderne Trockenplatte ist gegen die ultravioletten Strahlen ungemein empfindlich und diese hohe Empfindlichkeit kommt der Spectralwissenschaft ausserordentlich zu statten. Zeigt doch die moderne Trockenplatte allen lichtquellen elektrischen Ursprungs gegenüber ihre höchste Empfindlichkeit nicht etwa im sichtbaren Spectrum, sondern weitab davon im Ultraviolett. Photographirt man das Spectrum irgend eines Metallfunkens, so entwickelt sich jederzeit zuerst das ultraviolett, und erst, wenn man länger belichtet, tritt das sichtbare Spectrum hervor. Es ist aber keineswegs das ganze ultraviolette Licht, was dem sichtbaren voraneilt. Nur ein Theil davon zeichnet sich durch photographische Ueberlegenheit aus. Alles Licht, das jenseits der Kadmiumlinie No. 24 wirkt, braucht zu seiner Aufnahme beträchtlich längere Belichtungszeit. Die Empfindlichkeit der

Platte nimmt von dieser Linie - ihre Wellenlänge beträgt 2266 AE an mit der Brechbarkeit der Strablen sichtbar ab, und sinkt, bei Anwendung grosser Aufnahmeapparate, in der Gegend der Wellenlänge 2000 sogar auf Null hinunter. 2000 AE dürfte demnach annähernd die kleinste Wellenlänge sein, die sich mit den gegenwärtig am meisten im Gebrauch befindlichen grossen Gitterapparaten noch beobachten lässt.

Versucht man diese Wirkungsgrenze mit einem kleinen Apparat zu photographiren, dann erweitert sich das Beobachtungsgebiet um eine ansehnliche Strecke, und die gewöhnliche Bromsilbergelatine erweist sich, bei hinreichend kurzer Focalweite und gehöriger Lichtdurchlässigkeit des optischen Körpers, sogar bis zur Wellenlänge 1820 geeignet. Dieses relative Grenzgebiet kleinster Wellenlänge gehört nach umfassenden Versuchen, die ich im Jabre 1890 anstellte, einem Apparat an, dessen Focal weite 180 millimeters (Fraunhoferlinie D.) betraegt.

Der Umstand, dass das photographisch wirksame Spectrum um so weiter ins Ultraviolett hinausläuft, je kürzer die Brennweite ist, besagt deutlich, dass der Ort der photographischen Wirkungsgrenze eine Function der Dicke der Luftschicht ist, die die Strahlen auf ihrem Wege zur photographischen Platte zu durchsetzen haben. Versucht man nun, von dieser Thatsache ausgehend, die Luftschicht noch weiter zu vermindern, dann bemerkt man zwar, dass sich die photographische Wirkungsgrenze noch um einige Linien kleinerer Wellenlänge entfernt, allein der Längenzuwachs des Wirkungsbandes ist so unbedeutend, dass der Erfolg die Mühen und Kosten der Herstellung eines derartigen kleinen Spectrographen nicht lohnt. Es gewinnt sonach den Anschein, als habe man hiermit das wahre Grënzgebiet der wahrnehmbaren Lichtstrahlen kleinster Wellenlänge erreicht. Bestärkt wird man in solcher Annahme noch durch die Thatsache, dass das Fluorescenzspectrum ungleich früher, bei Wellenlänge 1852 verlischt, und demzufolge zur Beobachtung aller stärkerabgelenkten Strahlen ganz ungeeignet ist. Stände uns nicht die photographische Platte, sondern nur die fluorescirende Platte zu Gebote, so würde die kleinste Lichtwelle, die wir noch wahrnehmen könnten, nur das Längenmass von 1852 AE haben. Man sieht hieraus, dass beide Grenzwerthe nur eine ganz relative Giltigkeit haben. Aehnlich der fluorescirenden Substanz, die schon von Wellenlänge 1852 an nicht mehr leuchtet, könnte ja möglicherweise auch der photographischen Platte die Fähigkeit fehlen, von Allen Strahlen, deren Wellenlänge kleiner als 1820 ist, einen entwicklungsfähigen Eindruck anzunehmen. Diese Ueberlegung leitete mich, als ich vor nunmehr zwei Jahren eingehende Versuche mit Strahlen des brechbarsten Ultravioletten anstellte, und nicht ohne Erfolg. Es ergab sich hierbei, dass es nur der Mangel an Empfindlichkeit der damals angewandten lichtempfindlichen Platte, keineswegs ungenügende Energie der Lichtstrahlen war, die meine Versuche jenseits 1820 zu keinem befriedigenden Resultate kommen liess. Ich gewahrte ferner, dass die Strahlen schon in der das lichtempfindliche Silberkorn umschliesenden Gelatinehülle erstickten, ehe sie zur Einleitung des Zerfalls dieses Kornes gelangten. Die Gelatine des Plattenüberzugs bildete sonach die Ursache meiner photographischen Misserfolge im äussersten Ultraviolett. Die Kenntniss dieser wichtigen Thatsache führte mich zur Präparation einer neuen Platte, die sich in der Folge zur Photographie aller Strahlen jenseits Wellenlänge 2260 besser eignete, als die vorher benutzte Gelatineplatte.

Die neue Platte verhält sich den Lichtstrahlen gegenüber durchweg ganz anders wie die Gelatineplatte. Wenig empfindlich gegen alle Strahlen des sichtbaren Spectrums und der wenigerabgelenkten Strahlen des Ultravioletten, wächst ihre Erregbarkeit von 2260 an bis in die Gegend von 1860. Bei 1860 scheint sie, wenigstens allen elektrischen Lichtquellen gegenüber andere Lichtquellen erzeugen niemals so starkabgelenkte Strahlen - die höchste Empfänglichkeit für Lichteindrücke zu besitzen. Weiter nach der brechbarern Seite hin sinkt ihre Empfindlichkeit etwas, doch bleibt die Wellenlänge 1820, bei der die Gelatineplatte aufhört empfindlich zu sein, ohne allen hemmenden Eindruck auf sie. Kräftig und klar gezeichnet, gibt sie das spectrale Wirkungsband auch jenseits 1820. Arbeitet der Spectralapparat mit einem Prisma, dann scheint es, als wollten die Lichtmassen, die diesem,

für das menschliche Auge in ewige Nacht gehüllten Strahlenbereiche entquellen, gar kein Ende nehmen. Mit jeder folgenden Region, die man zur Aufnahme einstellt, meint man das Endgebiet der kleinsten Lichtwellen zu erreichen. Aber es ist fast, als flōhe die kleinste Welle, die überhaupt noch photographisch zu fesseln ist, um so behender ins fernste Ultraviolett hinaus, je näher ihr die Fessel der lichtempfindlichen Platte rückt.

Schon jetzt weist meine neue Platte jenseits 1852 ein Spectrumband auf, dass das gesammte Wirkungsgebiet der Bromsilbergelatine um mehr als das dreifache an Länge übertrifft, und gleichwohl lässt auch die letzte meiner Aufnahmen noch der Hoffnung Raum, dass jenseits des Randes ihrer Platte noch photographisch wirksames Licht existirt. Vorläufig gehört aber diese letzte Aufnahme, ohngeachtet solch' günstiger Aussicht, doch demjenigen Gebiete an, das ich gegenwärtig als die Grenze der kleinsten Lichtwellen bezeichnen muss. Die Photographie des Nachbargebietes hiervon stösst zur Zeit,- aus Grunden, deren Erörterung hier zu weit führen würde, - auf Hindernisse, die sich, sofern es überhaupt möglich ist, nicht ohne grosse Anstrengung werden beseitigen lassen.

Fragt man nun nach dem Masse der kleinsten Lichtwelle meiner Ultraviolettaufnahmen, dann muss ich leider bekennen, dass mir im Augenblick eine bestimmte Antwort hierauf nicht möglich ist. Wellenlängen lassen sich im luftleeren Raume, an den meine Aufnahmen gebunden sind, nicht so leicht ermitteln wie in der Luft, und die geplanten Messungen der Wellenlängen des äussersten Ultraviolett haben darum auch besonderer Vorbereitungen bedurft. War es doch überhaupt zweifelhaft, ob sich die übliche Methode der Messung der Wellenlängen auf den in Rede stehenden Lichtbereich werde anwenden lassen. Meine Vorversuche hierzu gehen zur Zeit ihrem Abschluss entgegen, und die mir vorliegenden Resultate berechtigen zu den besten Hoffnungen. Unter solchen Umständen kann ich das Mass der kleinsten Lichtwelle, die meine Aufnahmen aufweisen, vorläufig nur schätzungsweise und mit Vorbehalt nennen. Es dürfte dieses Mass 1000 AE nicht überschreiten, ja eher kann es um ein gutes Theil kürzer sein.

Der Wellenlänge 1000 entspricht eine ausserordentlich hohe Schwingungszahl des Lichtäthers. Während die brechbarsten Sonnenstrahlen wenig mehr als 1000 Billionen Schwingungen in der Secunde ausführen, schwingt ein Strahl von der Wellenlänge 1000 in derselben Zeit dreibillionenmal. Mit Schwingungszahlen so enormer Höhe hat der Spectroskopiker bisher noch nie zu rechnen gehabt, und gleichwohl liegt es nicht ausser dem Bereich der Möglichkeit, dass wir über kurz oder lang die Wirkungen des Lichtaethers bis in die nächste Nähe der Wellenlänge Null verfolgen werden, wo der ungeheuren Anzahl seiner Schwingungen kaum noch der Massstab des Endlichen gewachsen ist.

THE SOUNDS OF R.1

BY ALEX. MELVILLE BELL.

THERE seems to be special need for a better understanding of the sounds of R. No element of speech is so variously pronounced -in dialects and by individuals. The fundamental organic action from which all the varieties are derived is a frictional emission of breath or of voice between two surfaces in the breath channel. Thus we may make an R in the throat,― producing the effect which, when prolonged, is called a groan; or in the guttural passage, between the back of the tongue and the soft palate - a mode which is dialectically common in many countries. A less definite variety is formed between the arched top of the tongue and the roof of the mouth. This is common in the United States. Another and the normal English form of Ris produced between the point of the tongue and the upper gum. This is sometimes modified by inversion of the tongue within the palatal arch, or by addition of guttural or of labial contraction. The pointtongue R is also varied by advancement of the tongue to or between the teeth. In a common English affectation the seat of R is transferred fron the tongue to the lips, so that R has the sound of W. Of these varieties one may be characteristic of a

1 Paper read before the Phonetic Section of the Modern Language Association, December. 1891.

dialect, another a mere individuality, but they are all effects of only one organic action performed at different parts of the mouth.

Another series of R's results from a trilling or rattling organic vibration instead of a mere friction of the breath or voice. Thus a trill of the epiglottis is heard as one form of R; a trill of the uvula is another and very common one; and a trill of the point of the tongue is the regular form of R in North Britain and Ireland. The Spanish R has a more prolonged rattle of the same kind. The trill has often the effect of a syllable; as in Scotch and Irish, where it converts the grammatical monosyllables world, harm, mourn, etc., into the phonetic dissyllables wor-rld, har-rm, etc.

These trills involve a strong pressure of breath and a harshness of phonetic effect, in contrast to which is a form of R of simple vowel quality, without friction or vibration; as in (ə)ise and (a)ound, for rise and round.

A similar vocalic effect is also heard for R wherever it is not followed by a vowel; as in here, care, fire, store, tour, are, war, term, first, etc. The syllable-like quality of this sound is distinctly felt after the close vowel ē, and less distinctly after open vowels, because their mouth cavities differ so little from that of R.

In Early English R was always trilled, as it continues to be in Scotland, where most of the characteristics of Early English are still prevalent. But in modern English the trills have been softened away wherever R follows a vowel, until little is left of the R but its vowel quality. We are accustomed to the entire omission of R in negro speech, where do and sto are all that we hear for door and store; but in educated utterance there is some phonetic effect left in R even where it is least manifest. Such delicate shades of sound are the distinguishing marks of refinement in pronunciation, and they should be carefully preserved by teachers and by writers on phonetics.

In a book recently published in England the learner is taught that R is silent in such words as farm, serve, lord, prayer, weird, etc. Had the statement been that the sound of consonant-R is not heard in these words it would have been correct, but the R is certainly not "silent;" it has a phonetic effect of its own, soft and vowel-like, but a quality wanting which the words would not have their characteristic pronunciation.

That there may be no mistake as to the teaching in the work referred to, the reader is specifically told that the words arms and lord are exactly the same to the ear as the words alms and laud. Now what is the sound of R which baffles the discrimination of this writer? Let us magnify it, as in a microscope, by prolonging the elementary sounds. First let us put "alms" and "laud" under the microscope:

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Here between the vowel and the m or d there is interposed a gliding connective sound, so that the vowel is not stopped sharply by the consonant, but its quality is gradually changed by a lift of the tongue, verging towards but not quite reaching the position for R. This is all the sound that R has, in modern English, before any consonant or when final in a word. But it is something more than nothing; and something that is essential to the correct utterance of any word containing R before a consonant.

Among the sounds of R may be reckoned the influence of R upon other sounds. The mouth cavity for R being very large, any closer vowel preceding R is, as it were, stretched at the point of junction, so as to assimilate with R. Thus a pure è is with difficulty pronounced before R; a pure a is never, in Anglican speech, heard before R, but a is "stretched" to eh, as in air, chair. So, too, o and oo before R have a more open than their usual formation, as in old-ore; pool - poor.

These widened sounds of o and oo are distinctly different from the sound of aw; yet in the book before referred to the words shore and drawer are said to have the same vowel; and the words

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