Zbc ^University of (TbicaaoPrice $J*00 FOUNDED BY JOHN D. ROCKEFELLER Single Copiesper Year 5 CentsUniversity RecordPUBLISHED BY AUTHORITYCHICAGOGbe VXniveisity of Gbtcago ipress^ j -'¦¦.. ¦ ' ¦¦ ¦ ¦ - ¦. ., . . ... j..j.VOL. I!, NO. 30. PUBLISHED EVERY FRIDAY AT 3:00 P.M. OCTOBER 22, 1897.Entered in the post office Chicago, Illinois,. as second-class matter.CONTENTS.I. The Importance of Astrophysical Research andthe Relation of Astrophysics to other PhysicalSciences. By Professor James E. Keeler, Sc.D. 239-246II. The Dedication of the Yerkes AstronomicalObservatory, Williams Bay, Wis. - - - 246-250III. Current Events 250IV. The Calendar - ----- - - 250The Importance of Astrophysical Research and the Relation of Astrophysics to other Physical Sciences.*BY PROFESSOR JAMES E. KEELER, SC.D.Director of the Allegheny Observatory.The domains of the physical sciences are not, like thepolitical divisions represented on the map, capable ofbeing defined by boundary lines traced with mathematical precision. They pass into one another by imperceptible gradations, the unity of nature opposingitself to rigid systems of classification. Thus thereoften exists between two allied sciences a broadground, belonging to each, yet exclusively the propertyof neither, which may be so extensive and fertile as tojustify the development of a new science for its specialcultivation. And such a science not only subservesthe purpose for which it was created, but it has thefurther special importance that, by promoting an?Address delivered at the dedicatory exercises of the YerkesAstronomical Observatory, Williams Bay, Wis., Thursday,October 21, 1897. exchange of knowledge between its previously established neighbors, by investigating the cause ofdisagreements between them, by comparing theirmethods, and possibly by detecting errors in theirresults, it tends to bring them into more perfect coordination.Such is the nature of the science which ProfessorLangley has called the new astronomy, and which isalso, and perhaps more generally, known as astrophysics. Its high development has in fact been sorecent that its name is found in only our latest dictionaries. It is closely allied on the one hand toastronomy, of which it may properly be classed as abranch, and on the other hand to chemistry andphysics; but it assumes wide privileges, and it is readyto draw material which it can use with profit fromany source, however distant. It seeks to ascertain thenature of the heavenly bodies, rather than their position or motions in space — what they are, rather thanwhere they are ; and for my own convenience I shalluse the terms astrophysics and astronomy to denotethe sciences of which these aims are respectivelycharacteristic. Yet here again the line of demarka-tion cannot be sharply drawn, since the measurementsof celestial motions that cannot be dealt with by themethods of the older astronomy is one of the mostimportant tasks of the astrophysicist. That which isperhaps most characteristic of astrophysics is thespecial prominence which it gives to the study ofradiation. The complex nature of white light, in par-240 UNIVERSITY RECORDticular, is never lost sight of, and its consequences arethoroughly exploited.That the older astronomers made no efforts systematically to study the nature of the heavenly bodies, isto be ascribed to the seeming hopelessness of such anattempt in their day, rather than to a lack of interestin the subject, or a slight appreciation of its importanceon their part. They did in fact seek explanations ofsuch phenomena as they could observe, and the beginnings of astrophysics are to be found far back inthe past. But the curious speculations of Sir JohnHerschel on the structure of the Sun's photosphereshow how inadequate was the supply of facts to serveas a basis for a science of solar physics in Herschel'stime. The conception of living organisms a thousandmiles long, floating about on the Sun's surface, andshining with the intense brilliancy of the photosphere,seems to us extraordinary, and even grotesque. Tolose its strangeness it has to be considered with reference to the contemporary state of knowledge. Butthe fact that only fifty years ago it was regarded as anadmissible supposition by one of the most eminent ofastronomers helps us to realize how rapid has been theadvance of astrophysical science. It was only afterthe discovery was made, that the light which revealsto us the existence of the heavenly bodies also bearsthe secret of their constitution and physical condition,that the basis of a real science was obtained. Thespectroscope placed new and hitherto undreamed ofpowers in the hands of men. It is to the astrophysicistwhat the graduated circle and the telescope are to theastronomer.The study of astrophysics does not at present seem tohave a very direct bearing on the practical affairs ofeveryday life. If to this statement the objectionshould be made that the study of solar radiation islikely to lead to a practical method of utilizing theSun's heat as a source of mechanical power, I shouldsay that such a discovery, if it is ever made, is muchmore likely to be the result of an ingenious applicationof principles already known. What the future mayhave in store we cannot tell, but at present the statement I have made holds good. With respect to practical usefulness, therefore, astrophysics does not possess the same claims to consideration as astronomy,which has obviously important applications in furnishing standards of time, and in surveying, geodesy, andnavigation, and in addition to these, an immense indirect influence on thousands of ordinary affairs. Yeton such grounds it is not probable that any astronomerwould care to base a claim for his science. Astronomylong ago reached that state of perfection which sufficesfor the practical ends I have mentioned, and is still pursued with undiminished vigor. Both astronomyand astrophysics take their stand on a higher plane,where it is a sufficient justification for their existencethat they enable us better to understand the universeof which we form a part, and that they elevate thethoughts and ennoble the minds of men.In considering the importance of astrophysical research I have therefore regarded the question from apurely scientific point of view. Even with this restriction there is room for a considerable diversity of opinion, since the elimination of the human element fromthe question is impossible. Scientists are men. Everyman is naturally inclined to attach special importanceto that in which he is himself specially interested.Personal preferences, or even prejudices, may enterinto the estimation in which a branch of learning isheld. But, setting these aside, there are grounds fordifferences of opinion which are entitled to respect.What importance is to be attached, for example, tothe proof, now brought almost within our grasp by theimprovement of spectroscopic instruments and methods, that the law of gravity is operative within thestellar systems, as well as in the system of our ownSun ? Doubtless there are some who are satisfiedwith the moral certainty that we already possess, andto whom the proof just mentioned would merely affordthe satisfaction of inking in, on a printed form, thepenciled words which had already been written in itsblanks; while there are others who would regard theformal proof alone as entitled to consideration. Ihave even heard widely different opinions expressedby eminent astronomers as to the scientific importanceof a problem so fundamental as the exact determination of the distance of the Sun.The degree of importance which we attach to anewly discovered fact or principle is influenced bymany circumstances, among which we cannot fail torecogniz3 some of the failings of human nature. Whenprogress is rapid, individual achievements lose theirprominence, like mountain peaks rising from a highplateau. The discovery of an asteroid was once anotable event. Now it attracts little attention, outside of a small circle of observers, and it is probablethat few of us could say just how many of these littlebodies have been brought to light during the pastyear. In astrophysics discoveries of the highest significance have succeeded one another so rapidly thatthey are now taken as a matter of course.The bearings of a discovery on existing knowledgeare sometimes not immediately perceived, and its truescientific importance is not appreciated until theseare revealed in the fullness of time. Other circumstances might be mentioned, but these are sufficientUNIVERSITY RECORD 241for my purpose, which is to show that there is nocause for surprise if opinions differ as to the exactvalue of astrophysical research. It is because thescience of astrophysics is so young — so distinctly inthe formative stage — that I have ventured to discuss aquestion which, in due time, will settle itself.A feature of astrophysical research which I do notwish to leave unmentioned is the interest which is feltin it by the public. Those who are interested in theresults of science, but who care little for .methods, andknow nothing of elegant forms of analysis, are naturally more attracted by the view of the heavenly bodieswhich astrophysics presents, than by the view whichis obtained from the point of view of the older astronomy. Astrophysics paints its picture in the brightercolors. A star, regarded as a center of attraction, oras a reference point from which to measure celestialmotions, awakens little enthusiasm in the popularmind ; but a star regarded as a sun, pouring out floodsof light and heat as a consequence of its own contraction, torn by conflicting currents and fiery eruptions,shrouded in absorbing vapors or perhaps in vastmasses of flame, appeals at once to the popular imagination. Both branches of astronomy share in theadvantages which follow this awakening of popularinterest ; for that popular interest in any science is tobe deprecated is to my mind utterly inadmissible.The cultivation of a pure science is possible only inthose communities where such an intelligent interestexists. Without it we should not be here today. Itis splendidly manifest around us. The only possibledanger to be feared is, that interest in results whosesignificance is readily understood may lead to anundervaluation by the public of results which are ofthe highest importance, but which only the trainedspecialist can fully comprehend ; and this danger willbe avoided if scientific men publicly express their ownappreciation of results which belong to the latterclass.Popular interest, which is not of this character, butwhich has no purpose other than amusement, is lessdesirable. " It is the universal law," says Macaulay,"that whatever pursuit, whatever doctrine becomesfashionable, shall lose a portion of that dignity whichit had possessed while it was confined to a small butearnest minority, and was loved for its own sakealone." Macaulay is here referring to a temporaryinterest in scientific matters which prevailed amongfashionable circles in the reign of Charles the Second,— to what would now be called a " fad." In our owntime science occasionally suffers in much the sameway. It is to be regretted that the habitability of theplanets, a subject of which astronomers profess to know little, has been chosen as a theme for exploitation by the romancer, to whom the step from habitability to inhabitants is a very short one. The resultof his ingenuity is that fact and fancy become inextricably tangled in the mind of the layman, who learnsto regard communication with the inhabitants of Marsas a subject deserving serious consideration (forwhich he may even wish to give money to scientificsocieties), and who does not know that it is condemnedas a vagary by the very men whose labors have excitedthe imagination of the novelist. When he is made tounderstand the true state of our knowledge of thesesubjects he is much disappointed, and feels a certainresentment towards science, as if it had imposed uponhim.Science is not responsible for these erroneous ideas,which, having no solid basis, gradually die out andare forgotten. Thus it cannot long suffer from outside misapprehension, while the sustained effort necessary to real progress is in the end a sufficient safeguardagainst the intrusion of triflers into its workshops.In astrophysics sustained effort is as necessary as itis in other branches of science. There is an impression in some quarters that the results of astrophysicalinvestigation are easily obtained. That this is insome cases true may readily be admitted. I cannotregard it as a reproach. It is one of the advantages,to which I have referred, by bringing new methods tobear on old problems. What an effort to grasp something tangible we observe in the earlier writing onFermat's principle ! What a groping in the dark aftera principle felt rather than seen ! and how obviousthe same principle is from the point of view of the wavetheory ! In a field so wide and so little explored asastrophysics there must be novelties which can begathered with comparatively little effort, and whichmay nevertheless be of no small importance. Butthere are also problems whose solution calls for theexercise of the highest intellectual faculties, and forthe most strenous exertion.In astrophysics difficulties are met with quite different from those of physical astronomy. There a vastvariety of highly complex phenomena are to be referred to the operation of a well-known and extremelysimple law. The mental discipline there obtained isof the highest order, and it is hardly necessary to saythat a training in the methods of the older astronomyshould be regarded as an indispensable preparationfor astrophysical work. But in astrophysics, as in the'sciences of chemistry and biology, there are difficulties which arise from an imperfect knowledge of thelaws governing the phenomena observed. The discovery of unknown laws and principles, as well as the242 UNIVERSITY RECORDexplanation of phenomena by laws already known, isone of its most important objects.I have referred to the differences of opinion whichusually exist, with reference to the value of a newscience. There may be some who view with disfavorthe array of chemical, physical, and electrical appliances crowded around the modern telescope, and wholook back to the observatory of the past as to aclassic temple whose severe beauty had not yet beenmarred by modern trappings. So mankind, dissatisfied with present social conditions, looks back withtender regret to the good old times of earlier generations, yet rushes forward with the utmost speed. Maywe regard the eagerness of pursuit as a measure ofthe value of its object? That the importance ofastrophysical research, considered with respect bothto its own ends and to its bearing on the advance ofknowledge in other fields, is already great, and that itwill grow steadily from year to year, is naturally myown belief. In a general way I have considered someof the reasons on which it is founded, and I now wishto call your attention to a few specific cases, whichillustrate my general remarks, and in which I thinkthe importance of astrophysical science is manifest.Some of the most noteworthy advances in astronomy and in astrophysics have been made possible bythe introduction of photography. The photographicplate not only gives a permanent record of what theeye can see, but, by its integrating power continuedthrough long exposures, it builds up a picture frorn^light impulses too feeble to affect the sense of vision.Thus it has been discovered that vast regions in thesky are filled with diffuse nebulae, which (since theapparent brightness of a surface cannot be increasedby any optical device) must ever remain unseen. Thisinformation, which the photographic plate alone couldfurnish, is itself most wonderful and suggestive. It ishowever but a part of what the same plate may yield.Whoever has studied Professor Barnard's admirablepictures of the Milky Way in Scorpio must have observed how accurately the distribution of the smalleststars corresponds to that of the extended nebulositywhich fills this part of the sky, and at the same time howstrikingly the nebulous matter is concentrated aroundthe brightest stars in the constellation. Bright stars,faint stars and nebulosity are unmistakably physically related, and hence at the same order of distancefrom the earth ; and from this it follows that the realBizes of the stars are of entirely different order.Here is a fact having a most important bearing on thequestion of stellar distribution, brought out by thesimplest possible means. It is perhaps beyond thereach of more elaborate methods. And in this case it is to be observed that the evidence would not bemade clearer by any further treatment of the material.The positions of the stars and the density of thenebulosity might be measured, and the results mightbe tabulated — but all to no purpose ; for, if the datayielded by observation were in the form of measurements, the first step toward their interpretation wouldbe the construction of just such a chart as the photograph places ready in our hands.Of very great importance to the new astronomy hasbeen the investigation of the conditions of maximumefficiency of its chief instrument, the spectroscope, bythe methods of physical optics. The theory of resolving power, introduced by Lord Rayleigh, and quiterecently elaborated by Professor Wadsworth, has beenespecially fruitful. It has done away with the oldidea that the efficiency of a spectroscope is measuredby its dispersion, and may be trusted to destroy intime some musty traditions concerning the magnifyingpower and definition of astronomical telescopes. Thetheory has also been extended so as to include thespectrograph, in which the photographic plate takesthe place of the eye at the observing telescope of thespectroscope. The designing of spectroscopes hasthus been placed on a thoroughly scientific basis. Atthe same time the demands for accuracy in the practical construction of the instrument have been greatlyraised. The objectives, the prisms, the fitting of themechanical parts must be the best possible. Hencethe spectroscope has become an instrument of precision, worthy of a place among the most refined instruments of practical astronomy, and fitted for the classof work now most needed in astrophysical research.A familiar example of the mutual obligations ofallied sciences is found in the first measurements ofthe velocity of light. Perhaps a somewhat parallelcase may have to be recorded by the future historianof science. Spectroscopists have tested the validityof what is known as Doppler's principle, by which themotion of a body in the line of sight is determinedfrom the observed displacement of its spectral lines,and have at the same time proved the capabilities oftheir instruments, by means of the velocities of theearth and heavenly bodies furnished to them byastronomy. It is not impossible that this also is areversible process, and that measurements of thevelocities of bodies in the solar system may give oneof the best methods of determining the dimensions oftheir orbits.Numerous cases could be mentioned in which astro-physical investigations have contributed to our knowledge of the chemical elements. Of these the firstwhich naturally presents itself is one of the mostUNIVERSITY RECORD 243recent. The element helium was discovered first inthe Sun (as its name implies), then in the stars, thenin the nebulas, and at last by Professor Ramsay it was"run to earth." It had an important place in celestial chemistry long before it was known to terrestrial science ; and, on account of its rare occurrenceand seeming inertness, it is quite possible that but forthe spectroscope of the astrophysicist we should haveremained forever ignorant of its existence. To theastrophysicist, however, it was known only by the occurrence in its spectrum of one bright line. Laboratory investigations soon revealed its complete spectrum, and then the astrophysicists were able to recognize, as belonging to helium, a large number of lineswhose origin in the heavenly bodies they had beenunable to discover. Our knowledge of the heavenlybodies may be greatly advanced when the propertiesof this remarkable element shall have been thoroughlystudied.It is not necessary, however, to seek illustrations innew elements. The complete series of hydrogen lines,to which belong the few lines that are ordinarily seenin the laboratory spectroscope, was discovered byHuggins in the spectra of the white stars ; and a newseries, which had previously been seen by the eye oftheory only, and which, so far as I know, has not yetbeen produced artificially, has recently been found byPickering in the spectrum of the star Zeta Puppis.Another familiar element is calcium. Its ordinaryproperties are well understood. But under the conditions met with in the Sun and stars it behaves in amysterious manner. Notwithstanding its considerableatomic weight, it floats quietly high above the surfaceof the Sun, where other heavy metals are only occasionally present in consequence of violent eruptions. It istrue that the apparently abnormal spectrum of cal-,cium under these conditions has been shown by SirWilliam and Lady Huggins to be merely the result ofextreme tenuity of the luminous vapor ; but the existence of calcium at such great heights, under anyconditions whatsoever, seems to point to some remarkable property of the element which is unrecognizableby the methods of ordinary chemistry.The spectrum of a substance is not the same underall circumstances. In some cases a change occurssuddenly when certain critical conditions are reached ;in others the change is gradual and progressive. Bystudying these changes in laboratory experiments, andcomparing them with what we see in the observatory,we are able to arrive at some definite conclusions respecting the conditions which prevail in the stars,while the same comparison often throws light on thephenomena observed in the laboratory. It has been shown, for instance, that the spectrum of magnesiumgives a means of estimating the temperatures of thestars ; and the same criterion enables us to recognizein the stars temperatures vastly exceeding the highestthat have been produced on the earth. Thus thescience of astrophysics allows us to extend our investigations to temperatures which the resources of thelaboratory cannot furnish.It may be well to mention an example of the difficulties, to which I have referred, arising from ourimperfect knowledge of the laws which underlie phenomena constantly observed. Recent comparisons ofthe spectra of the Sun and metals, made at the JohnsHopkins University with the concave grating spectroscope of Professor Rowland, have proved that spectrallines may not merely be widened by increased pressure of the radiating vapor, but that they may beshifted bodily ; while the still more recent investigations of Zeeman show that a line may be widened (andat the same time doubled) under the influence of astrong magnetic field. It is true that in both casesthe effect produced is very small. It could not lead tomistakes in identifying stellar lines, or to appreciableerrors in measuring celestial motions. But the factthat the spectrum of a substance varies according toits circumstances, which are as yet only imperfectlyunderstood, shows us the necessity of exercising caution in interpreting the spectral phenomena presentedto us by the heavenly bodies. At present these spectral variations increase the difficulties that the astrophysicist has to contend with. Eventually they willbecome additional and most valuable sources of information.The discovery by Kayser and Runge of line series inthe spectra of the common elements has a most important bearing on the wor£ of the astrophysicist. Itprovides him with the means, long greatly needed, ofdeciding with certainty whether or not lines in celestial spectra are identical with lines in the spectra ofterrestrial substances. On the other hand, as we havealready seen, he is sometimes able to supply thephysicist with missing data.From the point of view of the old astronomy the mostimportant result of the introduction of the newmethods has been the determination of motions in theline of sight by means of the spectroscope. Themethod has been tested so often, and with such uniform success, that there is no longer any doubt as tothe correctness of the principle on which it is based,or to the accuracy of the results which it is capableof yielding in competent hands. It is directly applicable to one of the great problems of astronomy, — thedetermination of the direction and rate of the Sun's244 UNIVERSITY RECORDdrift through space. From the proper motions of thestars, furnished by the methods of the older astronomy, the direction of the Sun's motion can be deduced, — and, under certain assumptions as to thestars' distances, the rate of motion ; but it is evidentthat the latter element of the problem must be subject to very considerable uncertainty. With the spectroscope velocities are directly measured in miles persecond. The two methods may be combined. It isprobable that the most accurate determination of thedirection of the Sun's drift can be obtained by comparing proper motions, while the most accurate valueof the velocity is that given by the spectroscope.Thus, by the cooperation of the two blanches ofastronomy, there is measured in space a base line ofconstantly increasing length for a great sidereal tri-angulation. At present the material afforded by spectroscopic observation is not sufficient for this greatwork. The observations must be treated statistically,and statistical methods can be applied successfully toonly a large mass of data. What is now needed,therefore, is observations of more stars, i. e., fainterstars, and the German government is building a largetelescope for the observatory at Potsdam (where photography was first applied to this class of observations), in order that the work may be continued.There is room, however, for the employment of otherlarge telescopes in the same field. The multiplicationof observations for this purpose is no more to bedeprecated than the multiplication of observations forthe exact determination of star places.Solar physics, from which the wider science of astrophysics has been evolved, offers problems so numerousand so complicated that I cannot even mention them,still less enter into a discussion of their bearing onother branches of knowledge. And what can I possibly say of their importance ? The Sun is to us thegrandest of material objects. It is the source of practically all our light and heat; of practically all ourmechanical power ; absolutely the support of all ourlives. What wonder that we seek for knowledge ofits nature by all the ways that we can find! Theseways are opened through astrophysical research. Infew of the inquiries that I have referred to can themethod of light analysis be dispensed with. In mostof them it offers the only chance of success.I have time to mention only one new method ofsolar research. The most notable contribution tosolar physics within the last few years has been theinvention of the spectroheliograph by Hale & Des-landres. With this instrument photographs of theSun are taken by strictly monochromatic light, whichmay be chosen from any part of the spectrum. If the part selected is the middle of the "K" line, thepicture essentially represents the distribution of calcium vapor on the disk of the Sun, and the presenceof other elements is ignored. This is, in fact, the lineusually chosen, partly on account of the conspicuouspart played by calcium in solar phenomena, andpartly for other reasons, which it is not necessary togive. The possibilities of the method are obvious.By an ingenious modification of his instrument Halenow photographs on a single plate the Sun coveredwith all its spots and faculse, and surrounded by allits prominences ; and all this is done in a few minutes,in full daylight! Could the corona be added, thetriumph would be complete; but the corona yetremains unconquered in its stronghold, though theattack is being vigorously pushed.No branch of observational astronomy seems to bein so backward a state as the representation of thesurface features of the planets. Although the Moonhas been photographed with splendid success, and theplanets with results that are encouraging and suggesttive, we still rely (in the case of the planets) on the oldmethod of hand drawing used by Galileo. The fallibility of the draftsman is well known. It has beenillustrated again and again. Yet there seems to be acurious habit among some observers of regarding adrawing, when once made, as invested with highauthority — as that of a standard established by legislative act. A photograph, if it could be made, wouldbe free from the errors of the draftsman, and from apersonality which is recognizable in all hand drawings,and which, though it is scarcely to be classed as anerror, it would be desirable to avoid. Here, then isanother opportunity, for the new methods. There isno reason to suppose that it is impossible to obtainphotographs of the planets which will show all thatthe eye can see, although there are many reasons toknow that it will be very difficult to dp so. Theinstruments for this purpose would have to be quitedifferent from those in general use, and there, wouldbe few occasions, in even the most "favored regions ofthe earth, when they could be employed. Difficultieswould also arise from the rapid rotation of some of theplanets. But this is not the place to discuss thenecessary conditions. It is only fair to say that Professor Schseberle of the Lick Observatory has alreadybeen experimenting in this direction — with what success is not yet generally known.Passing to stellar spectroscopy, a field broader eventhan that of solar physics is opened before us, forthe Sun, although paramount in his own system, isonly one of the stars. In a general way, the spectraof the stars have been observed, and classified accord-UNIVERSITY RECORD 245ing to their character, and objects of unusual interesthave been noted for future investigation — many arare specimen has been meshed in Harvard's widelyextended net ; but the detailed study of individualspectra has just begun. For this purpose large telescopes are desirable, it not absolutely necessary. Manyobservations of precision required in the older astronomy are best made with small telescopes. But instellar spectroscopy light is all-important, and whilemuch can doubtless be accomplished with small telescopes, there is probably nothing that cannot be donebetter with large ones. Even in solar spectroscopy,where the supply of light is abundant, a large imageis required for the study of individual parts of theSun's surface.No department of astrophysics has profited more bythe introduction of photographic processes than stellar spectroscopy. To the advantages of photographyalready mentioned there is here to be added anothernot less important. Owing to atmospheric disturbances the image of a star dances about on the slit-plate of a spectroscope placed in the focus of a telescope. The spectrum is not only faint, but tremulous,and to measure the lines in it by visual observation islike trying to read a printed page irregularly illuminated by flashes of light. These irregularities do notappear on the photograph. They disappear in theprocess of integration. Negatives obtained with thespectrograph can be directly measured under a microscope, or enlargements can be made from them in theusual manner. In this way photographs of star spectra are now made which are comparable, with respectto accuracy and wealth of detail, to Kirchhoff's famousmap of the solar spectrum. "It is simply amazing,"says Professor Young, with reference to the Drapermemorial photographs, "that the feeble, twinklinglight of a star can be made to produce such an autographic record of substance and condition of theinconceivable distant luminary."Let us consider for a moment some of the questionsin this field that are open for investigation. Themotions in the line of sight of all stars within reach ofthe largest telescopes have to be measured. This important line of research has already been referred to.The relation has to be ascertained between the variousclasses of star spectra and the probable order of stellarevolution. It now appears practically certain thatall the stars are not made according to a single pattern,and that they cannot be fitted into a single scheme ofdevelopment. The Wolf-Rayet stars, the stars withbanded spectra, the stars with bright-line spectra, theplanetary nebulas, the spectroscopic binaries, the variable stars require the most careful attention. Vari ables of the Mira class should be followed with thespectroscope as far as possible from their maximum,and the spectral changes which accompany the lightvariation of other stars, whether due to phenomena ofemission and absorption, or to relative motion ofbodies in a revolving system, should be studied withthe most powerful instruments.The discovery by means of the spectroscope ofbinary stars which are far too close for resolution withour most powerful telescopes, and which are recognized in their true character by a periodic doubling oftheir spectral lines, has brought to our knowledgestrange and wonderful conditions of orbital motion.Such a system as that of Spica, where two bodies likeour Sun revolve around each other like the balls of agigantic pendulum, in a period of only four days, at adistance no greater than that which separates thesixth satellite of Saturn from its primary, must haveremained forever unknown to the older astronomy.Between these spectroscopic binaries and the mostrapidly revolving doubles visible in the telescope thereis a wide gap, the cause of which is obvious. Theconditions favorable to discovery in the two cases aredirectly opposed, and doubtless a large class of starslies at present just beyond the reach of either method.But this gap may be bridged over by means of sucha great telescope as we see before us today, while thework necessary to accomplish this end will open upstill another field for research. It has long been recognized that the position micrometer and the spectroscope, taken together, are theoretically competentto determine the real orbits in space of the components of a double star ; hence, also, the masses of thecomponents and their distance from the earth. Untilrecently the question had only a mathematical interest. But the small velocities to be expected in thecase of any double star whose components can be separately distinguished with the telescope are nowalmost, if not quite, within reach of the spectroscope,and the investigation of such doubles has acquired aphysical interest.Here I must close my review of the important questions before the astrophysicist, with the consciousnessthat it is most remarkable for what it leaves unnoticed. I have said nothing of questions relating tothe photography of comets and their spectra, the rotation of the planets or the absorption spectra of theiratmospheres, the colors of double stars, the spectra oftemporary stars, the measurement of obscure wavelengths ; nothing about stellar photometry, the application of interference methods to spectroscopic research,the exploration of the infra-red spectrum. But I willnot trespass further on your patience. In all the fields246 UNIVERSITY RECORDthat I have mentioned there are noble problems, worthyof the best efforts that can be given to their solution. Torealize their importance, think how ill we could sparewhat we have already won ! What a blank would beleft in our knowledge of the heavens if the results ofastrophysical research in our own generation werestricken out !The future should look bright, indeed, as we view ittoday. Munificence and skill have provided thissplendid Observatory with means for promoting knowledge in both the older and the newer branches of thesublime science to which it is dedicated. Its magnificent equipment will be used by men who have wonmerited distinction in both the older and the newermethods of research. It has the cooperation andsupport of a great institution of learning. From thishappy union of ability and opportunity we have reasonto expect results of the highest import to the newastronomy, and to its allied branches of physicalscience.But, lest any words of mine should give rise to expectation that may not be fulfilled, I wish to say oncemore that important results are not necessarily of astriking or surprising character. We can hardlyassume that every increase in telescopic power willbe followed by the discovery of new planets or satellites. Such discoveries, if they come, will be welcome;but they should not be expected. There may be nomore planets or satellites, yet undiscovered, in thesolar system. But we may confidently expect fromthe work of this Observatory those results whichthrow light on the dark places in nature, and which,therefore, though they may not stimulate the popularimagination, are of the very highest importance, forthey are indispensable to scientific progress.The Dedication of the Yerkes Astronomical Observatory-williams bay, wis.I.The Dedicatory Exercises of the Yerkes Astronomical Observatory of the University of Chicago tookplace at the Observatory Building, Williams Bay, Wis.,October 21, 11:00 a.m.-3:00 p.m.The exercises were opened with prayer by Dean E.B. Hulbert of the University. The address was delivered by Professor Keeler, Director of the AlleghenyObservatory (see pp. 239-246 of this Record).PRESENTATION BY MR. YERKES.Mr. Yerkes, in presenting the Observatory to theUniversity through the President of the Board ofTrustees, said : Mr. President, Ladies and Gentlemen :After five years of patient waiting and incessantlabor, we are brought together to perform the agreeable duty which has been in our minds during thewhole of that period, namely : the . dedication of thisObservatory.It was in October of 1892 that Dr. Harper and Professor Hale arranged for the manufacture of the telescope and building the Observatory, and since thattime the work has been incessant. Before this, however, three years had been spent' in preparing therough glass, making eight years in all which wasrequired to produce what we now have before us. Theanxiety of those who were so deeply interested in thework can scarcely be imagined, for as they followed itstep by step from its incipiency to its finish, manydoubts and fears naturally crossed their minds. Asno glass had ever been made of the size of this therewas no criterion to go by, and it was necessary to leaveeverything to the future. Then again, there was therisk of accident, and when the glass was safely lodgedin its final resting place, the hearts of many who arenow present beat much more freely and with greatersatisfaction than they had since the projecting of thework. A priceless gem to these gentlemen was at lastin safety, and when we consider what would have beenthe result in case of accident — six years of sincerework being thrown away and six years more wouldsurely elapse before the same results could beobtained — we can imagine something of their feelingsof satisfaction when they saw the final accomplishment of their labors. That we have done -a good deedand one which will revert to our satisfaction we haveno doubt.The science of astronomy, while being the oldestextant, has been, we may say, the most neglected. Itis in no way commercial, and that may be one of thechief reasons. Its promulgation has always been confined to a class of enthusiasts who felt an interest intheir work and gloried in the achievements whichthey attained.Five thousand years ago astronomy was studied, butit was not until six hundred years before the Christianera that any progress had been made in it. Greekmythology used it as a romance, with but little ideaof its truthfulness, and up to the beginning of theseventeenth century, when the telescope wTas inventedby Hans Lipperhay and applied by the great Galileo,but little was known of the science. From that timeon through the work of Newton, Lagrange, Laplace,Dominicus, Cassini, Flamsteed, Bradley, Herschel,Bessel, and others equally celebrated, good progresswas made, and during the last half century there havebeen greater advances than ever before. This is owingto the fact that we now have the ability to determineUNIVERSITY RECORD 247correctly by instruments which are late inventions,matters that were never dreamed of. It is to thegreat telescopes that the ardent workers look for encouragement for their labors. Accurate means havebeen devised for recording the observations, while thephotographic plate, together with the spectroscope,have been applied with the most astonishing results.As I said, one reason why the science of astronomyhas not more helpers, is on account of its being entirelyuncommercial. There is nothing of moneyed value tobe gained by the devotee to astronomy; there isnothing that he can sell. Compared with electricityand other sciences of like character, there is thegreatest difference; consequently, the devotee of astronomy has as his only reward the satisfaction whichcomes to him in the glory of the work which he does,and the results which he accomplishes.These are some of the reasons why you are gatheredhere today and why this edifice and its contents havebeen erected.That the work will produce good results, I am, aftera thorough examination, fully satisfied, and my satisfaction is still more intense when I learn of the greatand enthusiastic men which the University of Chicagohas gathered around it for the purpose of takingcharge of the work to be performed in this Observatory, and I therefore with the .fullest feeling of satisfaction and pleasure, turn over to you this structurewith all its contents, feeling satisfied that it is now inthe best of hands, and that the labors here will beserious, conscientious, and thoroughly done. I feelthat in your attempts to pierce the mysteries of theuniverse which are spread before you by our greatCreator, the enthusiasm of your natures will carryyou to success.acceptance on behalf op the trustees.Mr. Martin A. Ryerson, President of the Board ofTrustees of the University, accepted the gift in a briefspeech. He said :Mr. Yerkes, Members and Friends of the University of Chicago :It is with great personal pleasure, increased by thefeeling that I am expressing a wide-felt sense of publicappreciation, that I perform the duty of representingthe Board of Trustees of the University of Chicago onthis occasion.Any hesitation which one might feel on account ofthe difficulty of adequately expressing the sentimentswhich are here aroused gives way before the conviction thM, when all has been said today, there willremain a continuing and growing appreciation of this great gift of which this ceremony, important as it is,is but the initial public manifestation, and which will,after all, be the true reward of the donor.When the many expressions of gratitude have foundutterance on this occasion, there will remain what mustbe a source of even greater gratification to Mr. Yerkes,the continuing and increasing usefulness of his greatgift. I use the word usefulness not only because I amconvinced that we are here at the inception of a greatwork which will justify itself by the practical value ofits results as well as by the ideal nature of its aims,but also because I feel that in an age when so muchof the ability and energy of the community is devotedto the advancement and the improvement of materialConditions each new agency for the upholding of theideals of life through the cultivation of science for itsown sake has a usefulness of the highest order. Weneed not fear the materialism of an age in which anintense pursuit of the useful and the practical isaccompanied by an ever widening conception of trueutility, in which the satisfaction of intellectual demands is keeping pace with the meeting of physicalrequirements. Let us by all means be practical if wecan, at the same time broaden our conception of themeaning of the word so that it may include thatdevelopment of the intellectual side of life withoutwhich any improvement of material conditions is absolutely vain. While recognizing fully the great practical services which astronomy has rendered to theworld, I still feel that its proudest claim to recognitionand appreciation must dwell in its tendency to establishand maintain in the feelings of mankind the convictionthat, amid the services of science, the increase of knowledge for the sake of knowledge is not the least.Mr. Yerkes :On behalf of the Board of Trustees of the Universityof Chicago, I accept your generous gift, and I assureyou that we feel sincerely grateful for the new forcefor the advancement of learning which you haveplaced in our hands. We appreciate highly the liberality with which you have from the beginning encouraged the broadening conception of this great work,and we desire to bear testimony to the breadth of theviews which you have always expressed in relation toits aims and its scope.We shall endeavor to so administer the trust committed to us as to fulfill your highest hopes and expec-... tations.address on behalf of the faculties.Then followed the address of the President of theUniversity, as follows :248 UNIVERSITY RECORDMr. Yerkes, Representatives of Institutions ofLearning, Members of the University, Ladiesand Gentlemen:We have been the witnesses of a great act. We havelistened to the significant words by which the man,whose largeness of heart made possible the erectionof this temple of science, has transferred the same tothe University in whose keeping it shall foreverremain. The donor has now made formal presentation of this great contribution to the cause of science,and the President of our Board of Trustees has formally accepted it. This is the latest act of a longseries, and very naturally, as this act has been performed, my mind has been carried back through these^.ve years of serious and laborious struggle, to thatmoment when with words, perhaps still fewer innumber and with a spirit which, at all events, seemed,if possible, more gracious, Mr. Yerkes took the initialstep in an undertaking, the name and fame of whichhave gone around the world. On Tuesday morning,October 4, 1892, when the doors of the Universityhad been open only three days, Mr. Yerkes consentedto purchase for the University the forty-inch objective. Under date of December 5, 1892, he wroteas follows :" It was with much satisfaction I learned from youthat a lens for a large telescope could be purchasedimmediately ; and I informed you that I would purchase the lens and have it finished ; that I would alsopay for the frame and mountings of the telescope, sothat the two together would make a perfect telescope,to be the largest in the world, namely, with an objective disk of forty inches clear." You gave me figures which you supposed the telescope would cost ; and I readily agreed to invest thatmuch money in the undertaking."Since then I have felt it proper that the telescopeshould have a home, to be paid for by me ; and I haveconcluded to add to my gift an Observatory necessaryto contain the instrument." I have already authorized you to arrange with theowners of the glass for the transfer of their rights init to the University." I have made a contract with Alvan G. Clark & Sonsfor finishing the glass. I have also agreed upon theprice, and have everything ready for the signing ofthe contract with Messrs. Warner & Swasey for theframe and mountings."From that day to the present moment, the work ofmaking plans for mountings and buildings, the workof negotiation for location, and the work of actual construction has gone on — slowly, to be sure, but withoutinterruption. It seems, as we look back upon theseyears, almost impossible to calculate the time andeffort expended by all concerned upon the undertaking of which today we celebrate the completion. In our thought of the gift as a whole, we must notlose sight of the several parts which together constitute it. There was first of all the forty-inch objective,the greatest and last work of its maker, Alvan G,Clark. We see before us the equatorial mounting ofthe objective, which, with the 90-foot dome above usand the rising floor on which we sit, are evidence ofthe skill and thorough workmanship of the builders,Messrs. Warner & Swasey. The objective cost, whenfinished, $66,000, the equatorial mounting, $55,000, thedome and rising floor, $45,000. To these there mustbe added as distinct gifts, the 30-foot dome for thesoutheast tower which cost $7000, the 26-foot domeand mounting of the Kenwood telescope ; likewise thestellar spectrograph, constructed by Mr. J. A. Brashear,costing $3000. Besides all these, the building withits piers for the instruments, its steam heating plant,engines, dynamos, and motors, the cost of which hasbeen in round numbers $135,000.On this occasion we must make acknowledgment ofthree additional gifts which have already come to theObservatory. First of all, the grounds on which it hasbeen built, consisting of 55 acres valued at $50,000, acontribution of Mr. John Johnston, Jr.; second, theinstruments and equipment of the Kenwood Observatory, presented to the Yerkes Observatory by Mr.William E. Hale ; and third, the gift of Miss CatharineBruce, of New York City, of $7000, for a 10-inch photographic telescope with building and dome.The question of the selection of a site was perhapsthe most difficult question which presented itself. Inorder to ascertain the scientific requirements of a site,it was deemed wise to confer directly with the leadingastronomers of the country. A series of questionsprepared by the Director of the Obseratory, ProfessorHale, was sent to a selected number of Americanastronomers. A consensus of opinion upon the various questions proposed was thus obtained. Theclaims of twenty-six different localities were considered, namely, Morgan Park, Tracy, Highland Park,Downer's Grove, Hinsdale, Mt. Pleasant, WesternSprings, La Grange, Glen Ellyn, Lake Geneva,Elmhurst, Elgin, Rockford, Peoria, Aurora, Wau-kegan, Belvidere, Sycamore, Marengo, Lena,Kankakee, Warren, Oregon, Princeton Dixon,Pasadena, Cal. Most of these localities were visited.The objections which might be urged against eachplace were annotated. About this time the trusteesthought it wise to appoint as a committee with powerto select the site, the President of the Trustees, andthe President of the University. In a letter datedFeb. 4th, 1893, Mr. Yerkes wrote to the President ofthe University : "I will leave the question of siteUNIVERSITY/ RECORD 249entirely to you and to Mr. Ryerson." The Committee, however, did not desire to assume so great aresponsibility, and although given power to act, madea full report to the Board of Trustees in which waspresented the choice of the Committee, namely, LakeGeneva, together with the reasons for the choice.From this report I may be permitted to quote one ofseveral paragraphs urged in favor of this location :"It is conceded by all concerned that no site thus farsuggested combines in itself so many of the requirements, or any of the requirements to so great a degree.The site is high and beautifully located. The atmosphere is clear, without danger from the encroachmentof manufacturers, railroads or electric lights." Thereport of the Committee was adopted by the Trustees,and the much debated question was at last settled.I shall not occupy your time in describing the building which you have been invited today to visit. It issufficient to say that, in addition to the provisionordinarily made, it includes completely equipped instrument and optical shops, in which apparatusdesigned by members of the staff for speciaMnvestiga-tion can be constructed. At the present time amachine for ruling optical gratings, an equatorialmounting for the 24-inch reflector (the mirror ofwhich has already been made by Mr. Ritchey), and amirror of 60 inches aperture are in course of construction.Has the 40-inch object glass stood the test, andare the atmospheric conditions satisfactory ? Thesequestions have already been answered many times,Test after test has been applied. The following statement is made officially by the Director :(1) Objects beyond the reach of any other telescopein existence have been discovered. The closest doublestars have easily been divided by Professor Burnham.The spectrum of the Sun's atmosphere close to thesurface has been found by Professor Hale to containa great number of bright lines hitherto unknown.The photographs of stellar spectra taken show thatthe glass, because of its great light-gathering power,is particularly suitable for spectroscopic observationof the stars. (2) The steadiness of the telescopemounting is so great that Professor Barnard finds hismicrometrical measures of star positions, diameters ofplanetary nebulae, positions of the satellite of Neptune, etc., to be far more precise than any he haspreviously obtained. (3) The atmospheric conditionsat night are frequently very fine indeed. The bestseeing here is not surpassed by the best seeing at theLick Observatory, though in the course of a yearthere would be more good nights at Mt. Hamilton, On the other hand, the atmospheric conditions duringthe day are much superior to those of the LickObservatory. The conditions for solar work, considering both instruments and atmosphere, are probablymuch better than those enjoyed by any other observatory.Mr. Yerkes : — President Ryerson has expressedto you the appreciation of the Board of Trustees forthis great gift towards the resources of the University,and has emphasized most appropriately the spiritualelement characterizing a gift made in an environmentin which the materialistic occupies so prominent aplace. It is fitting that expression also be given onbehalf of the Faculties of the University and themembers of the Astronomical staff. We realize thatyou have greatly increased the glory of the Universityby furnishing an equipment which makes it possibleto discover new and important facts in the structureof the universe ; that you have furnished stimulusand incentive to many of our number to devote theirlives most earnestly and sacredly to the search fortruth ; that you have honored the City of Chicago,the Northwest, the entire Valley of the Mississippi,by planting in its midst an institution which throughthe centuries will contribute to the uplifting of menand the upbuilding of character. We appreciateabove all the simplicity and the sincerity of themotive which prompted you to make this gift, and thepurpose which has controlled you throughout theseyears, during which the gift has taken tangible form.Men of science and men of learning in every land willreceive and acknowledge the benefits of this gift.The Yerkes telescope is not an institution of Chicago,or of Wisconsin, or of the United States merely. Itwill become one of the institutions of the world,aiding and interesting those wTho speak many differentanguages, who live in many widely separated lands.We realize that through your gift the opportunity hascome to us as members of the faculty of the University of Chicago to perform important service in thecause of science. For the opportunity of doing whatbut for your gift we could not otherwise have done,we are profoundly grateful. If it were possible foryou to derive a tithe of the satisfaction from yourgift which the giving of it will bestow upon each oneof us, you will have been rewarded. It has been saidthat " science, like virtue, is its own exceeding greatreward." This, if true, holds good not only of thosewho may, technically, call themselves scientists, butas well of those who make scientific work possible bytheir munificence.On behalf of students and instructors, on behalf of250 UNIVERSITY RECORDthe University of today, and the University of thefuture, I thank you for the word spoken five years ago,for the word you have spoken today —the word whichgave the University the gift.D* * *The exercises were closed with the Dedicatoryprayer by the Rev. James D. Butler, of Wisconsin.Current Events.At the meeting of the Botanical Club on October 6Dr. Magnus, the celebrated cryptogamic botanist ofBerlin, was present and gave a short address. Dr. C.J. Chamberlain gave a review of Miss Sargant's paperon the spermatogenesis of Lilium Martagon. Mr. WD. Merrell gave an account of the controversy betweenProfessors Oltmanns and Berthold in regard to somephases of copulation in Ectocarpaceae ; and Mr. H. C.Cowles presented the results of Stahl's researches onnyctitropic movements in plants.In the Report of the United States Commissioner ofEducation for 1895-6, the first volume of which hasjust appeared, there is a chapter of over one hundredpages devoted to Commercial Education in Europe.It is made up of extracts from the report made in 1893to the American Bankers' Association, by Prof essorEdmund J. James, of the University, on CommercialEducation in Europe and of various addresses deliveredby him before the American Bankers' Association uponthe same subject. This is an indication of the rapidlygrowing interest in those branches of instruction forwhose promotion the projected school of Commerceand Philosophy in the University is primarily intended.The Calendar.OCTOBER 23-29, 1897.Saturday, October 23.Administrative Board of Physical CultureAthletics 8:30 a.m.Faculty of the Senior Colleges, 10:00 a.m.The Divinity Faculty, 11:30 a.m. and Sunday, October 24.Vesper Service. Kent Theater, 4:00 p.m.Union meeting of the Y. M. C. A. and Y. W. C. A.,Haskell Oriental Museum, Assembly Room, 7: 00p.m,Monday, October 25.Chapel-Assembly : Junior Colleges. — Chapel, CobbLecture Hall, 10:30 a.m. (required of Junior sCollegeStudents).Tuesday, October 26.Chapel-Assembly: Senior Colleges. — Chapel, CobbLecture Hall, 10:30 a.m. (required of Senior CollegeStudents).University Chorus, Kent Theater, 7:15 p.m.Informal Talks on Books of Today by Assistant Professor Crow, Lecture Room, Cobb Hall, 3 :00 p.m.R. L. Stevenson : ££. Ives; Kepplier: Varia; W. A. Quayle*The Poefs Poet.Botanical Club meets in the Botanical Building,5: 00 p.m.Wednesday, October 27.The Zoological Club meets in the large Lecture Roomof the Zoological Building, 4: 00 p.m.Assistant Professor Watas6 on "Protoplasmic Contractility and Phosphorescence.Regular meeting of the University Settlement Committee ; Faculty Room, 4:00 p.m.Prayer Meeting of the Y. M. C. A., Lecture Room.Cobb Lecture Hall, 7:00 p.m.Thursday, October 28.Chapel-Assembly : Divinity School. — Chapel, CobbLecture Hall, 10:30 a.m.Meeting of the Philological Society, Cobb LectureHall, B 8, 8:00 p.m.Papers by Head Professor W. Gr. Hale, and Professor G.L. Hendrickson.Friday, October 29.Chapel-Assembly ; Graduate Schools.— Chapel, CobbLecture Hall, 10: 30 a.m.The Mathematical Club meets in Ryerson PhysicalLaboratory, Room 35, 4:00 p.m."On Implicit Functions of Several Variables," by Dr*Hancock.Notes : " Computation of fba log x dx as limit of a sum,"by Mr. Emery ; " On Cantor" II, by Professor Bolza.Material for the TDSriVERSITY RECORD must be sent to the Recorder by THURSDAY, 8:30 A.M., inorder to be published in the issue of the same week.