&* MARINE BIOLOGICAL LABORATORY. Received U<, . M I (faf. Accession No. Given by \AAsU4rl Place, " ***flo book op pamphlet is to be removed from the liab- opatopy ulithout the pepmission of the Trustees. 3#r m& «2§fe tlttt H&F ipli m CARNEGIE INSTITUTION OF WASHINGTON YEAR BOOK No. 2 1903 PUBLISHED BY THE INSTITUTION WASHINGTON, U. S. A. JANUARY, 1904 PRESS OF JUDD &. DETWEILER WASHINGTON, D. C. : ' / CONTENTS Page Officers iv Articles of incorporation vi By-laws viii Minutes of third meeting of Board of Trustees x Report of Executive Committee on the work of the year xv Memorials of Abram S. Hewitt, William E. Dodge, Marcus Baker liii Accompanying papers I i. Report of Committee on Southern and Solar Observatories 5 Appendix A — Report on certain sites in Arizona and Cali- fornia ; by W. J. Hussey 71 Appendix B — Letters from various astronomers.. 105 2. Reports relating to geophysics 171 Report on geophysics ; by C. R. Van Hise 173 Construction of a geophysical laboratory ; by G. F. Becker. . 185 Investigations suggested 195 3. Proposed International Magnetic Bureau ; by E. A. Bauer 203 4. Archeological investigations in Greece and Asia Minor ; by T. D. Seyrnour 213 5. Mechanics of the human voice ; by E- W. Scripture 243 6. Fundamental problems of geology ; by T. C. Chamberlin 261 7. Archeological and physico-geographical reconnaissance in Tur- kestan ; by R. Pumpelly 271 Appendix — Estimates submitted by Advisory Committee on Anthro- pology 288 (Hi) BOARD OF TRUSTEES i 903- i 904 John S. Billings, Chairman Elihu Root, Vice Chairman Charles D. Walcott, Secretary The President of the United States The President of the Senate The Speaker of the House of Representatives The Secretary of the Smithsonian Institution The President of the National Academy of Sciences John L. Cadwalader Cleveland H. Dodge William N. Frew Lyman J. Gage Daniel C. Gilman John Hay Henry L. Higginson E. A. Hitchcock William Wirt Howe Carroll Charles L. Hutchinson William Lindsay Seth Low Wayne MacVeagh D. O. Mills S. Weir Mitchell William W. Morrow John C. Spooner Andrew D. White D. Wright (IV) OFFICERS President of the Institution Daniel C. Gilman Executive Committee Daniel C. Gilman, Chairman Charles D. Walcott, Secretary John S. Billings John Hay S. Weir Mitchell Elihu Root Carroll D. Wright Finance Committee Lyman J. Gage Henry L,. Higginson D. O. Mills Office of the Institution Bond Building, Corner of New York Avenue and Fourteenth Street Washington, D. C. (v) ARTICLES OF INCORPORATION CARNEGIE INSTITUTION OF WASHINGTON We, the undersigned, persons of full age, and citizens of the United States, and a majority of whom are citizens of the District of Columbia, being desirous to establish and maintain, in the City of Washington, in the spirit of Washington, an institution for pro- moting original research in science, literature, and art, do hereby associate ourselves as a body corporate for said purpose, under An Act to establish a code of Law for the District of Columbia approved March third, nineteen hundred and one, sections 599 to 604 inclu- sive ; and we do hereby certify in pursuance of said act as follows : First. The name or title by which such institution shall be known in law is Carnegie Institution. Second. The term for which said Institution is organized is per- petual. Third. The particular business and objects of the Institution are the promotion of study and research, with power : (a) To acquire, hold, and convey real estate and other property necessary for the purposes of the Institution as herein stated, and to establish general and special funds ; (6) To conduct, endow, and assist investigation in any depart- ment of science, literature, or art, and to this end to co- operate with governments, universities, colleges, techni- cal schools, learned societies, and individuals ; (c) To appoint committees of experts to direct special lines of research ; (d) To publish and distribute documents ; (o o SO oo — i ^ H $ n 2 i. < ^ ■** « ft *> -K. w Co •>» « S « « S co u 3 in .2* o CU CN oo O CM r-~ OS H UO lO rO o Tt uo uo uo Tt uo Tt u u ca -i5 - Tt o ■* I/O i-1 Os O ►h o f^OO 00 r^ o N "-1 N SO O N Tt uo CN O OssO rO m" co CsT CsT h" CN w OS O CO Os SO rO rO CN CN CO M to O CN O so t^ rO r— Tt CO Soi ■ -1-1 . X . 1) CU a .. n a •T3 cu « U o CO « 5^ &a t%% co 2 li- es x 0) C -M O rhW w CO . . u . . tu • m : ^ . « m be - s ^1 &,OhX. cu fl CI i — . pq (N (N -*-> c (N 1 tN o CO fl OS < d «* CO co Tt o cfl ^3 fl O 1) u a Os O oo 00 Os H lOO H\0 OSM O M to uo CN so ts CS! 3 CU S ? o 2 CD a o CO cu V-i • CU p CO ■l-> CU +J rrj 00 0 S oh * Os CO -M ."S "fi CO I-! &i cu Oh ■c u CO (0 CO 3 o I a CO g. Tj Vh > •fH CU o CU cu ^^ Vh • e 0 « ,°, T5 ooU,Jj 2- S 2 g 2* them in making up the schedule of proposed works. (i) Fundamental Meridian Observations. We regard meridian observations of precision, upon the brighter stars, to be of the first importance in any attempt to relieve the situa- tion in the southern hemisphere. In this we are sustained b)r the nearly unanimous verdict of those whom we have consulted. We are clear upon the proposition that the exact positions of about 6,000 stars (including all down to the seventh magnitude that are south of — 2o°of declination) should be determined by fundamental methods, both for the interest which this work commands as an inde- REPORT OF COMMITTEE ON OBSERVATORIES 20. pendent research and for the bearing it has on other works, including those here proposed. In this line of work, as in nearly all other departments of astron- omy, contributions from the southern hemisphere have always been deficient. With a few notable exceptions, there has been a lack of highly trained and experienced astronomers there. The recent ef- forts of the Cape Observatory in this line have been both skillful and energetic ; but the Cape Observatory alone is unable to offset the numerous observatories in the northern hemisphere engaged in the precise observation of standard stars. The result is that the weight of our knowledge of the positions and motions of the standard stars in the northern sky is fully five times that for the far southern sky. A single corps of observers transferred from the northern hemi- sphere, where its loss would not be a relatively serious matter, to the southern hemisphere, where its services are so much needed in this line, could reduce the existing discrepancy of weight in fundamental determinations for the present epoch by one half. It has been conclusively shown that the exactness of our knowl- edge of general drift in the motions of the stars, whether it arises from solar motion, rotation, or from any other source, depends almost wholly upon the number and precision of our fundamental determinations of the positions of the standard stars. The main battle is fought on this field. Furthermore, astronomy has now arrived at the point where, by comparatively little additional obser- vation, it will be possible to compute the motion of nearly every star brighter than the seventh magnitude in the northern sky with a fair degree of accuracy. With the observations herein proposed, the same thing, in a modified degree, would be true of the stars in the southern hemisphere. Not many more than one third of these stars has been reobserved during the last quarter of a century. This work accomplished, astronomers could hope to deal success- fully with problems of motion for all the stars visible without a telescope, and beyond that for all stars down to those which are one third as bright as the faintest visible to the ordinary eye — about 15,000 stars in all. This would give us the first opportunity ever offered for a comprehensive discussion of the solar motion and re- lated problems on a scientifically correct basis, with a liberal supply of material distributed over the entire sphere. This work would, therefore, possess a high scientific interest as an end in itself ; but it would also serve as an indispensable basis for the observation of planets and of the fainter stars. A scheme 30 CARNEGIE INSTITUTION of observation like that described further on under (2) would require this work as its foundation. In fact, there is scarcely a single de- partment of precise measurement in astronomy that would not be indebted to this work for a part of the data which it needs. The problem of observation here suggested naturally divides itself into two sections. The first would be concerned with the observa- tion by fundamental methods, and with the highest precision, of about 600 to 800 of the principal stars ; the second would involve the extension of this work by less rigorous methods to about 5,000 other stars — the entire work to be conducted in such a manner as to be systematical!}' consistent in all its parts, and to be a homogeneous whole. There can be scarcely a doubt that the ideally best result would be attained through the adoption of the transit and vertical circle, for the observation of the principal stars at least. This, however, would prove somewhat more costly in execution, and the completion of the entire work, if it should be carried through with these instru- ments alone, would be deferred somewhat longer than might seem desirable. The advantage of economy would attach to the use of a meridian circle for these observations. This would be increased, if the use of such an instrument that has already been thoroughly tested in the northern hemisphere could be procured, and we believe it can. The labor of a thorough investigation of the errors of graduation and other errors of such an instrument is, in itself, no slight task. What would be requisite for the purpose, here designed, would probably be equivalent to one full year of work by four observers. The degree of accuracy really attainable in the use of the meridian circle should not be sensibly inferior to that for a vertical circle. The distinct advantage of the latter is in the variation of method which it offers. For the present we should advise the employment of a meridian circle for this research, unless the proposed Southern Observatory should be established on a scale which would enable it to maintain for certain lines of observation the highest ideals. Whatever the precise methods of observation may be, the instru- ment, or instruments, employed should be used for at least two years in the northern hemisphere in the determination of the positions of the principal fundamental stars visible there. There would result a peculiar gain in precision through the comparison of observations with the same instrument upon the same stars, made alternately in the two hemispheres, by which certain errors of the instrument and REPORT OF COMMITTEE ON OBSERVATORIES 3 1 a part of the uncertainties in our knowledge of astronomical refrac- tion could be in a marked degree eliminated. The proof of this is already at hand in numerous comparisons of observations made con- temporaneously with different instruments in the two hemispheres. From these it can easily be inferred what would be the probable gain if both sets of observations were to be made with the same instru- ment. We think that this plan presents a unique opportunity which ought not to be neglected. If the meridian circle should be employed with a full corps of as- sistants the southern work here proposed could probably be accom- plished within four or five years from the date of beginning. It would involve about 40,000 observations of about 6,000 stars and about 4,000 observations of stars north of — 200 for the purpose of comparison and check. From four to seven observers and com- puters would be needed, with as man y more routine computers, in order to keep the work going continuously and the computations up to date. (2) Complete Observation of Stars to the Ninth Magnitude. The exact determination of the positions of telescopic stars down to the ninth magnitude and south of — 300 of declination is a work of high importance. The opinions of astronomers would differ as to the pressing nature of this work in comparison with the two suc- ceeding works mentioned in this schedule. As will be seen from the correspondence transmitted herewith, there are opinions of great weight equally positive in favor of each of these undertakings. The plan for meridian observation of faint stars is mentioned second in order because of its intimate logical connection with the investiga- tion already mentioned under ( 1 ) . The project to observe with meridian instruments the precise positions of all stars down to the ninth magnitude originated some- what more than thirty five years ago, and was adopted as the pecu- liar function of the Astronomische Gesellschaft '; which at that time assumed something of an international character. The importance of this project has been universally recognized. The original pro- gram for the northern hemisphere was completed under a coopera- tive arrangement. The extension of this work under the same auspices has been carried to — 220 of declination, and the observa- tory at Cordoba has pushed the work on to — 320 of declination. About one quarter of the sky remains to be considered. The com- 32 CARNEGIE INSTITUTION pletion of this one quarter would greatly enhance the value of what has been already accomplished. The demand for this work may be stated under three principal heads : i . The primary utility of this work would rest upon its immense importance in studies relating to the stellar system. The work mentioned already under (i) would enable us to study the structure and motions of the sidereal system so far as this is represented by stars to the seventh magnitude. The extension of this work by means of (2) would take us to stars of the ninth magnitude, for which the older records of observations contained observed positions of the greater part. We should then be able to extend our studies upon the sidereal problem to stars ten times as numerous and more than six times fainter than those of the seventh magnitude. The feasibility of reaping the full fruits of this undertaking through the present generation of astronomers is not so great as for the brighter stars, but that which would be demonstrably attainable now in this direction fully warrants the enterprise. Furthermore, the comple- tion of this monumental work, so that the accurate position of every star from the north to the south pole, down to the ninth magnitude, would be known for epochs near the beginning of the century, would be an achievement upon which the entire civilized world could look with pride. 2. The positions of these stars determined in this work would possess very great value as reference points in all micrometric work upon faint stars, nebulae, comets, and planets observed by means of extra-meridian telescopes. This alone was originally looked upon as fully warranting the labor of the entire enterprise. 3. This work would furnish the reference stars needed in the work of the Astrographic Chart, which has for its aim the determi- nation of accurate positions for all stars down to the eleventh mag- nitude. This forms the third step in a series of investigations which seek to determine the accurate positions of stars at successive epochs in order that we may ultimately learn their motions. The accuracy of which this third step is capable depends upon the accuracy of its basis, which must be the meridian observation of telescopic stars. The only difficulty is that the accuracy of the observations hitherto made under the program of the Astronomische Gesellschaft is not re- garded as sufficient for the purposes of the Astographic Chart, as Director Loewy has pointed out. He recommends as a substitute for (2) the special determination of the star positions required for REPORT OF COMMITTEE ON OBSERVATORIES 33 the Astrographic Chart. It will be found, however, that the so-called zone observation of telescopic stars may easily be brought to a very much higher grade of accuracy than that which has prevailed hith- erto, without any material sacrifice of the rapidity with which they can be made. This can be effected in three ways : (a) By the use of a superior instrument. (£) By the use of a more accurate and more extensive stand- ard catalogue, rendered possible under (i). (V) Through a better organization in methods of observation. Then with the addition of about one fourth the number of obser- vations which would be needed under (2), without reference to any ulterior use, we shall be able to complete the Astronomischc Gesell- schaft zones and at the same time meet the requirements of the Astrographic Chart ; and we strongly recommend that this pro- gram be adopted. The necessity of this extended program is all the more pressing because of the extremely doubtful probability that the observations for the basis of the Astrographic Chart can be secured by means of existing agencies with the requisite completeness and accuracy. The argument that the positions of all the stars down to the ninth magnitude (and fainter) in the southern hemisphere can hereafter be derived from the Astrographic Chart assumes that we may look for the completion of that undertaking within a few years. The probability that the completion of certain important sections of that work may be delayed for a longer time than would be desirable, however, seems to be warranted by an examination of the situation. On the other hand, it seems very desirable that the great undertak- ing entered upon thirty five years ago for the determination by meridian observation of the position of all stars down to the ninth magnitude in the whole heavens should be completed. The proposed Southern Observatory has here an opportunity to carry out a work which would have enough of intrinsic interest in and for itself, but which would possess the great added advantage of serving as the fundamental basis of another work even greater in extent than itself. It would also much increase the value of similar work already accomplished in the northern hemisphere. Further- more, it would scarcely be possible to carry out the work proposed next in order (3) in an economical, effective, and comprehensive way, as to stars in sensible motion, without the completion of (2). For this work there should be a corps of five or six observers and 34 CARNEGIE INSTITUTION computers and a somewhat larger staff of mere routine computers. Under these arrangements it should be possible in a good climate to turn out at least 20,000 accurate star positions each year, and to make all the computations necessary to put them in catalogue form. Since not more than 200,000 observations would be required, the entire work should be completed within ten years from beginning — possibly in less time. (3) Measurement of Stellar Parallax. The determination of the distance of individual stars is one of the severest tasks in the science of observation. The results already obtained during a period of more than sixty years, but chiefly during the last fifteen, are not free from troublesome discordances that seem to encourage pessimistic views. Yet a review of the work which has been accomplished, together with that of the larger amount which is now in progress, affords great encouragement that we shall be able to determine average distances of classes of stars with a very satisfactory degree of precision. This is the important thing we need to know in our first studies of the structure of the sidereal system. The two great questions to be solved are : (a) What is the relation of brightness to distance ? Are the stars of the sixth magnitude as far removed on the average from those of the second as the relation of brightness alone would lead us to think? According to this relation, the sixth magnitude stars should be on the average rather more than six times as far removed from us as are the stars of the second magnitude. Is this really the fact ? It is a question for measurement to decide. (&) What relation to distance has apparent motion on the face of the sky? Are the stars which appear to move athwart the sky nine tenths of a second per year three times nearer us than the stars which move three tenths of a second per year ? It seems very probable that this is approximately the case, and that apparent motion is a better criterion of distance than apparent brightness. Whether this conjecture is correct or not can be settled only by actual measurements of distances. The decision upon these points is a fundamental necessity in the stellar problem, because it opens the way for a much more powerful and economical solution of questions in relation to distribution in distance through the discussion of meridian observations. That way is, to some extent, open now, but we need that certainty upon REPORT OF COMMITTEE ON OBSERVATORIES 35 the correctness of the fundamental principle (b) or of some modifi- cation of it which can only be had through direct measurement of the distances of a large number of stars. That such measurements in large numbers are practicable is demonstrated by the successful work of Gill and Elkin at the Cape and of Elkin and Chase at New Haven with heliometers, by Kap- teyn at Leiden and Flint at Madison (Wisconsin) with the transit, as well as by other observers. Some of the available methods for measurement of parallax are : By the use of heliometers. By the use of meridian transits. By photographic methods. By micrometrical methods. All these methods have been tried extensively ; the first has ap- parently proved most accurate ; the last, formerly employed almost exclusively, would probably be discarded now by common consent. Photographic methods have not hitherto proved entirely satisfactory perhaps, and yet it seems to be the almost unanimous opinion of those in the best position to judge that this method offers the greatest promise for efficient work on a large scale when properly used. The method of exposing the same plate at three successive phases of parallax, suggested by Kapteyn some years ago, is the one which seems to offer the greatest promise of economy in labor and precision in the result. From existing evidence it does not appear that the photographic method is likely to be very effective upon stars brighter than the fifth magnitude. The heliometer would probably be better suited for parallax meas- ures of bright stars. This method, though extremely precise, is slow and costly. It has been employed at the Cape of Good Hope in measurements upon a few of the far southern stars ; but, so far as is known, no work of the kind is now going on in the southern hemi- sphere. The Cape heliometer is now devoted to planetary observa- tions upon a new plan, a work very appropriate to the original purpose of the Royal Observatory at the Cape of Good Hope. Therefore, with the exception of the aid which might hereafter be rendered by the Cape heliometer, the entire field for the determina- tion of stellar parallax in the southern hemisphere is open to the Carnegie Institution, should it desire to enter it. This work could be undertaken with advantage on almost any scale. Without any idea as to what means might possibly be avail- 36 CARNEGIE INSTITUTION able, we are unable to suggest a definite program other than the restricted one which follows. In the first line it seems desirable that an attempt be made to measure the parallaxes of stars known to be in sensible motion. As the limit of such motion for a comparatively restricted work, one might take o."2 or even o."i. In order to identify the stars having such motions, and to measure the motions themselves, the sources of information are now very scanty. It would be almost a necessity to carry through (2) of the program — the meridian observation of telescopic stars down to the ninth magnitude. If this were not done it would still be necessary to make accurate meridian observa- tions of all stars observed for parallax. The number which would be at present available under this plan and south of — 200 of declina- tion would probably be considerably under 500, though others could doubtless be found without much difficulty. We would recommend the use of a photographic telescope of relatively long focal distance for this purpose. It should be of the highest optical perfection. It is quite possible that a three lens or four lens combi- nation would be advisable, in order to get sharp, round images over an area of at least four square degrees if possible. We suggest a telescope of 18 inches aperture and about 30 feet focal length. It would also be highly desirable to measure with the heliometer the parallax of many stars brighter than the sixth magnitude and south of — 200 of declination. A seven inch heliometer similar to those in use at the Cape and at New Haven would be suitable for this purpose. The stars selected should be chiefly those distin- guished for proper motion — several hundred in number. This would be in effect an extension of the parallactic survey which has been carried on so successfully at New Haven within recent years. We think that the services of two observers on this work for a period of at least eight years would result in an extremely valuable contribution to the solution of the stellar problem. For some years the project of a general Parallax Durchmnsterung has been brought to the attention of astronomers. This contem- plates nothing less than the determination of the approximate rela- tive parallax of every star down to the ninth or tenth magnitude. The inquiry would mean something like this : If we take as the unit of distance the average star of the ninth magnitude, what are the relative distances of other classes of stars, and what individual stars are especially near the solar system ? A program for this pur- pose is described in the letter which Professor Kapteyn has addressed REPORT OF COMMITTEE ON OBSERVATORIES 37 to the Committee in response to its request (Appendix B). This would be an immense undertaking, which would seem to demand the cooperation of several agencies before it could be properly under- taken for the entire sky. It would also be desirable to learn more of the practical capabilities of the method proposed before making any recommendations upon the subject. The plates which would be taken in the course of the attempt to determine the relative parallaxes of stars known to have sensible motion would themselves offer an opportunity for preliminary tests of the method and of the value of the expected result. It would also be easy to provide this in a more systematic form for restricted areas of the sky by the exposure and development of plates espe- cially for that purpose, provided the measurements and computa- tions for these plates could be arranged under a cooperative plan of limited extent, such as that suggested in the letter of Professor Kapteyn (Appendix B). In view of these considerations we are of the opinion that it would be advisable, in connection with the proposed Southern Observatory, to set up a photographic telescope of about 18 inches aperture and 30 feet focal length for parallax work on the southern stars, and that it would probably be found desirable to maintain it in constant operation for a period of eight years at least. The services of two skilled observers and a small staff of measurers and computers would be required. (4) Meastirement of Radial Motions. In close connection with the three projects already mentioned is another for the measurement of velocities of stars in the line of sight — i. e., radial velocity toward or away from the earth. A knowledge of these velocities is of the utmost importance, and since the accurate measurement of such velocities has become pos- sible, a most valuable source of information for verifying and enlarging the conclusions to be drawn from the discussion of proper motions has been placed in the hands of astronomers. In fact, through an adaptation of the investigations for solar motion in connection with these measurements of radial velocity, it is possible to obtain valuable conclusions as to the distances of various classes of stars having sensible proper motions. When a very large num- ber of such measurements upon stars distributed over the entire sky shall have been obtained, it will be possible to determine the velocity of the solar motion with great precision. It will even be 38 CARNEGIE INSTITUTION possible to obtain in this manner an absolutely independent check upon the direction of solar motion which, in a problem so impor- tant, will possess the highest philosophical value and will become a valuable test of fundamental hypotheses as to structure and motion in the sidereal system. Whether the stars are distributed with approximate uniformity in volume, and whether the motions are at random in every conceivable direction, are questions which require for a definite decision the added information which can be obtained by the measurement of radial velocities of large numbers of stars extending, if possible, somewhat below those visible to the unassisted eye, in combination with discussions founded on proper motions which result from me- ridian observations. What we now most need is such measurements for stars not visible from the observatories of the northern hemi- sphere. Scarcely anything in this line has been accomplished for the southern hemisphere. Recently the Lick Observatory has dispatched an expedition to Chile with the Mills three foot reflector to make such measurements, and the maintenance of this expedition has been provided for by Mr. D. O. Mills for three years. It may be expected to produce results of the highest importance — of impor- tance relatively several times as great as would attach to like efforts with the same instrument in the northern hemisphere. Thus we may hope to have at our disposal within a few years the measured radial velocities of practically all the stars in the whole heavens that are brighter than the fifth magnitude. This will be an extremely valuable result ; but it would be made far more valu- able if such measurements could be secured for a greatly increased number of stars over a greater range of magnitude. Are the velocities of the more distant stars the same on an aver- age as those of the nearer stars ? Are the peculiar motions of the stars, after abstraction of parallactic motions, the same in the direc- tions to and from the observer at different distances from the Milky Way ? In order to answer these and similar questions with sufficient weight of evidence, the objects for which velocities in the line of sight have been measured should number 2,000, if possible ; and in order to accelerate the rate at which results can be reached, we need telescopes of the largest possible light-grasp. There is no apparent obstacle, except cost, in the way of employing a telescope with a five foot mirror for this investigation. That an increase in the resources for the measurement of radial velocities of stars in the far southern skies is desirable, appears from REPORT OF COMMITTEE ON OBSERVATORIES 39 the fact that, while there is permanently located in the southern hemisphere only one telescope which is used for this purpose, and provision made for the use of another during three years, there are employed in this service in the northern hemisphere at least six large telescopes, each more powerful than any telescope installed at a permanent observatory in the southern hemisphere. The disparity in resources here presented is marked, and the call for a remedy seems to be imperative. It would therefore seem to be very desirable that the Carnegie Institution should enter this field and provide for use in the south- ern hemisphere the most powerful reflecting telescope that would be sanctioned by experience and the dictates of common prudence. The use of this in the measurement of radial velocities of southern stars should be provided for during six years at least. There would be needed a staff of two skilled observers and a half dozen meas- urers and computers. The additional argument in favor of the provision of a large re- flector to be used in the southern hemisphere will be found later, under (7), in this enumeration of proposed works. The observations specified under the four preceding heads are closely related to each other, and logically they are branches of a single enterprise — an endeavor to make a strong forward movement in the solution of the sidereal problem. We consider it extremely desirable that provision for all the works enumerated by us should be made in the proposed Southern Observatory, but in the event of necessary curtailment which does not extend to the entire program, it is to be hoped that such curtailment may not apply to either of the four projects thus far mentioned. (5) Observations of Double Stars. — A Large Refractor. The measurement of double stars has been in active progress for more than a century. For the past seventy years work in this line has absorbed a very large proportion of the energies devoted to astronomical investigation. Certainly the class of facts developed by these investigations have remarkable interest, and they have exerted a deep influence upon the thoughts of man as to his place in nature. That the law of gravitation apparently extends through- out the universe ; that suns revolve about suns ; that the orbits are usually elliptical, like those of the periodic comets ; that many of these bodies are larger and more splendid than our sun — these and 40 CARNEGIE INSTITUTION numerous other facts seem to lend a special significance to this branch of astronomy. Except incidentally, this work is not very closely associated with the stellar problem, and the immediate ad- vantage of a greater extension of work in this line in the southern hemisphere is not so apparent ; yet it should be remembered that no really large telescope has yet been applied for any great length of time to the measurement of double stars in the southern hemi- sphere, and while we put this project after the four already men- tioned, we entertain no doubt of its desirable character. It would seem very desirable that a telescope of about 27 inches aperture should be provided for this work. There should be a reg- ular survey of the entire southern sky for the discovery of new double stars, to complete similar surveys carried out at the Lick Observatory and elsewhere. Double-star work on the southern sky has come practically to a standstill, while it is still going on industriously at several observa- tories in the northern hemisphere. That a large telescope in the southern hemisphere should be devoted to double-star measurements for a period of about eight years seems to be evident. One observer and one assistant would be required. If a large refracting telescope should be provided for the proposed Southern Observatory it is very likely that certain micrometrical and other studies, apart from double-star observations, would be worth while, perhaps calling for the detail of another observer. This comparatively small expenditure would doubtless be well compen- sated in the increased utility of a costly telescope justified for an- other purpose. Possible combination of '(^) and (5). — In providing the instrumental means for carrying out (3) and (5) upon a restricted scale, it might be possible to combine the two telescopes required, so that one mounting and observing room would suffice. This would result in a very large saving in plant. The tubes of the two telescopes, each designed as perfectly for its peculiar purpose as if made for special in- struments, could be attached to the same declination axis. Parallax plates should be exposed in the early evening and late morning hours, in any case. The result would be that the parallax telescope would usually be unused during the four or five hours around mid- night, in order to avoid the use of the telescope at large hour angles east or west. During this period, if the parallax telescope were combined with the telescope for micrometrical observations the latter would be wholly free during four or five hours near midnight, the REPORT OF COMMITTEE ON OBSERVATORIES 4 1 hours which, on the whole, would be most suitable for the observer of double stars. This arrangement is not suggested as ideal, but as one which might be adopted should the program for (5) be carried out and that for (3) be somewhat restricted. In that event we think the ar- rangement here suggested would be very much preferable, as it cer- tainly would be very much more economical. (6) Variation of Latitude. The variation of the earth's axis of rotation is one of the newest and most interesting developments of astronomy. The facts relating to it have an intimate bearing upon the question of precision in meridian observations, in addition to the great interest which at- taches to it as a physical phenomenon. Astronomy has not yet formed an adequate explanation of its origin. Quite recently Mr. Kimura, of the Japanese international latitude station, has called attention to a singular phenomenon developed by the international observations, which may be referred to several possible explanations, none of which appear quite satisfactory. In consequence of this, Dr. Chandler, editor of the Astronomical Journal, points out the necessity for establishing three observing stations in the southern hemisphere — one at the Cape of Good Hope, another at Sydney, and still another about 30 miles south of Santiago de Chile. This propo- sition has been heartily indorsed by several high authorities, in- cluding the Royal Astronomical Society. The operation of these three stations would tend to fix and define this anomaly in the ob- servations beyond a doubt, and the result might be that the true cause of the phenomenon in question would be pointed out. Fur- thermore, the execution of this project would bring a most valuable contribution to the question of astronomical aberration. We are strongly impressed with the importance of this work and are of opinion that, if the stations at the Cape of Good Hope and Sydney could be provided for by other agencies, the Carnegie Institution would do well to take the responsibility of the station in Chile. The annual expenditure would not be very great, and this project need not stand or fall with that for the Southern Observa- tory, although it has a logical connection with it. The zenith telescope and observing shed required would not be costly, and two observers, without other assistants, would be able to take care of the observations and computations. 42 CARNEGIE INSTITUTION In addition to the undertakings we have already enumerated as offering a definite field of great usefulness for the proposed Southern Observatory, there are others which, in the judgment of many astronomers of high standing, deserve a prominent place in this enumeration. The following list briefly recapitulates some of these. (7) Astrophysical Researches. Should a large reflector be provided for the observatory in con- nection with (4) it could also be utilized with advantage for certain photographic and astrophysical researches of great importance to the advance of science. Among these are : (a) Spectroscopic researches upon red and variable stars to sup- plement similar researches in the northern hemisphere. {b) Photography of nebulae in order to make the record of similar works complete for the entire sky. (V) Spectroscopic examination of the nebulae for the purpose of ascertaining their motions in the line of sight, as well as in the interest of inquiries into their physical nature. These and similar works are named as supplementary to that mentioned under (4), not to be carried on to the detriment of the latter. (8) The Astrographic Chart. Allusion has already been made to the labors upon the ' ' Carte du Ciel," or Astrographic Chart. Director Loewy, president of the Astrographic Congress, informs us that there is a vacancy in one of the zones ; and he states that the services of the Carnegie Institu- tion would be very acceptable in filling the vacant place. There is no question of the importance of this great project for securing a photographic representation of the entire sky at the present epoch. The work has already progressed so far that its ultimate success is now practically assured. It would be most unfortunate should the completion of one or two sections be delayed far beyond the com- pletion of all the others, thus destroying the unity of epoch that is so desirable in all such works. This work requires the use of a thir- teen inch photographic telescope of a special type. This instrument would not be very costly. The services of two observers and of a small corps of measurers and computers would be required during about eight years. We think that the feasibility of undertaking REPORT OF COMMITTEE ON OBSERVATORIES 43 this work ought to be taken into serious consideration by the Insti- tution, should it be ascertained that there is no reasonable prospect of provision for it elsewhere. (9) Photometric Observations. Professor Seeliger urges the importance of precise photometry on the southern stars in the interest of problems relating to the structure of the sidereal system, and to supplement similar work carried on in the northern hemisphere. All the arguments which have been presented in relation to the first four numbers of this program apply to this. Statistical methods of investigation in this field have already led to significant and interesting conclusions, and we cannot doubt the power of this method, which has already proved such a valuable guide in affording reliable clues to the structure of the sidereal system. We think that Professor Seeliger' s suggestion is worthy of further inquiry and consideration. (10) Researches of Minor Scope. A number of researches of minor scope have been suggested by our correspondents, all of which are of importance. For some if not all of them it seems desirable that interest should be excited at existing observatories in the southern hemisphere to take up these works and carry them to a successful conclusion. One of the good results which we should hope from the proposed Southern Observa- tory would be that it would serve to stimulate interest in astronomy throughout the populations of the southern hemisphere. It will thus be seen that there is no lack of work of pressing im- portance to be done in the southern hemisphere. If an observing station should be established on a liberal scale for the execution of these works, it would still be a problem requiring wisdom and firm- ness to keep the program within practical limits and concentrated upon the furtherance of the great end desired. The Question of Site. We have given much attention to the question of a suitable site for the proposed Southern Observatory, but we are not j7et prepared to make a definite recommendation. For valuable information in regard to this question we are in- debted to Mr. H. C. Russell, Government Astronomer at Sydney, 44 CARNEGIE INSTITUTION New South Wales ; Mr. W. Ernest Cooke, Government Astronomer at Perth, West Australia ; Dr. John M. Thome, Director of the observatory at Cordoba ; Mr. Walter G. Davis, Director of the Argentine Meteorological Service, and Sir David Gill, Astronomer Royal at the Cape of Good Hope. We are greatly indebted to these gentlemen for the painstaking and valuable information with which they have favored us, for cordial offers of facilities, and for documents of interest which they have forwarded. We have also devoted study to the meteorological and climato- logical reports in regard to the countries crossed by parallels of latitude suitable for the location of the observatory. In a preliminary way it appears to us that the most promising localities are in New South Wales, in the vicinity of Sydney ; in South Africa near Bloemfontein, or on the Great Karoo plateau in Cape Colony, and near San L,uis, in Argentina. San Luis appears to have a very clear sky and a salubrious climate. It is only 16 hours by rail from Buenos Aires. It is measurably free from the fearful ' ' hondas ' ' or stifling hot waves which characterize the Andean plateaus further west, and the skies are remarkably clear. The latitude of Bloemfontein is rather smaller than is desirable, only 290 south, while — 300 would seem to be almost the northerly limit admissible. Yet we have from Sir David Gill, who has in- spected that locality in connection with the trigonometrical survey, the most favorable accounts of the wonderful transparency and steadiness of the atmosphere there, and of the remarkable number of clear nights, which is estimated at 300 annually, or about three times the number we experience upon the Atlantic seaboard. The elevation is about 4,000 feet above sea level. The mean annual temperature is, however, rather high. Our early reports in regard to Australia were favorable, and we decided to procure a careful test of certain sites in the vicinity of Sydney. In April of the present year Professor W. J. Hussey, of the Lick Observatory, was appointed to make telescopic tests and other examinations with reference to observatory sites. He was engaged up to the end of July upon explorations in southern California, looking for a site for the Solar Observatory. Soon after the com- pletion of this work he sailed for Sydney, on August 6, under in- structions to test certain sites in the neighborhood of Sydney in relation to which we had formed favorable opinions, confirmed by the personal testimony of Mr. Russell. Mr. Hussey is provided with an excellent portable telescope of nine inch aperture, of which REPORT OF COMMITTEE ON OBSERVATORIES 45 the object glass was most obligingly loaned by The Alvan Clark and Sons Corporation of Cambridge, Mass. , and of which the principal parts of the mounting were also loaned by the Lick Observatory, thus reducing the expense of the telescope to a nominal sum. With this telescope the character of the ' ' seeing ' ' is ascertained by sys- tematic tests at all the stations visited. This can be compared with the excellent conditions prevailing on Mount Hamilton, where Mr. Hussey has had many years' experience. Pending Mr. Hussey 's examination and report, it scarcely seems worth while to enter into a detailed discussion in regard to sites at the present time. If the proposed Southern Observatory should be organized upon a scale sufficient to secure the execution of the greater part of the works enumerated in our program, the question of site would be very important indeed, and we have so regarded it. It is essential that the climate should be healthy for astronomers engaged upon tasks so strenuous ; that there should be a large pro- portion of clear nights ; that the air should be reasonably transparent and exceptionally steady, and that, so far as possible, the ordinary comforts of civilization should be found in the environment of the observatory. In the search for a stimulating and healthful climate, and also in the interest of the meridian observations, it would be desirable to choose a latitude of 400 south or more. But in the southern hemisphere, in latitudes south of — 35 ° or — 400, the amount of cloudiness is apt to be very great, or the cli- mate is otherwise unsuitable. In other respects, as in what was formerly called Patagonia, some of the localities in high southern latitudes cannot be regarded as available. The vicinity of Hobart Town, Tasmania, offers many advantages, especially in the health- fulness and uniformity of its climate, but with the disadvantage of rain falling on nearly half the days of the year. The amount of clear weather in New South Wales, though superior to that of our Atlantic seaboard, is not quite all that could be wished. The ob- ject of the proposed observatory is to secure valuable observations in large masses by the expenditure of great energy during a com- paratively short term of years. This qualification is not the only one, however, and may possibly be regarded as compensated some- what if a locality can be found where the climate is healthful and where efficient routine assistants can be recruited from the sur- rounding population. The funds appropriated for the use of the Commission will suffice for what it has undertaken to accomplish ; but if site explorations 46 CARNEGIE INSTITUTION in South Africa or Argentina are desired, a further small appropria- tion will be necessary. Later, through the operations of Mr. Hussey and the kindness of Sir David Gill, the Committee expects to be in possession of better knowledge as to what may be advisable in this direction. BUTLDINGS. The question of buildings and other constructions necessary for the proposed observatory is one which cannot be discussed in its minute details until something shall have been determined as to the site. Since the idea of this observatory is that of a temporary observing station, to be occupied, perhaps, not more than ten or twelve years, our ideas of the construction required would be largely controlled by that fact. The necessity of providing for the equalization of the inner and outer temperature seems to prescribe for the observing rooms a form of construction which would not be very different whether the ob- servatory were to be temporary or permanent. The essential prin- ciple is that the walls should consist of an iron or steel framework, with an outer covering of wood, in the form of louver work, and an inner covering of sheet metal, such as galvanized iron. The efficiency of this form of construction has been fully tested and seems to leave nothing further to be desired. For the drum to carry a large dome, this form of construction would probably be as economical as any other that could be accepted. Wood might be used for the framework were it not for the necessity of an even and solid construction for the tracks upon which the rolling mechanism of roofs and domes is supported. For the meridian instruments, sliding roofs should be provided. The great superiority of these over the old form of shutters is now fully demonstrated. Since an important requirement for site is excellence of atmos- pheric conditions, it follows that the proposed observatory must be located at some distance from any large center of population. Consequently it would be practically unavoidable that provision should be made for housing the observing staff upon the observatory premises. This is an arrangement which is quite indispensable to the highest efficiency in any case. In any but an extremely excep- tional climate there will be a large proportion of nights in which the probability of clear sky during the first half of the night will be doubtful. If observers live within easy access to the instruments, much clear sky will be utilized that will inevitably be lost otherwise. REPORT OF COMMITTEE ON OBSERVATORIES 47 Furthermore, after long duty at the instrument the observer is in need of rest, and in order to attain it should not be subjected to the hardship of a journey on foot for a mile or two in the small hours of the morning. For those observers who are obliged to begin duty at some time after midnight, it is practically indispensable that their residences should be in close proximity to the instruments they are to use. Aside from these obviously practical considerations, it has been found by experience that the plan of housing the staff upon the observatory premises effects a real economy in the quality and quantitj' of output in relation to the total expenditure. We are of the opinion, therefore, that residences for the observ- ing staff should be provided upon the site of the observatory. All that would be needed would be small cottages of simple construc- tion, suitable to the climate. Equal simplicity ought to prevail in the construction of the office buildings required for administration, computing, library, and storage. Small work rooms would also be needed for the mechanical department. Staff and Organization. The question of organization for the proposed observatory is one which cannot be effectively discussed until something shall be known of the definite purposes of the Trustees in relation to its establish- ment. It goes without saying that no work whatever should be undertaken which cannot be put under the direction of assured^ competent and energetic astronomers interested in what they are to undertake. If the scheme should be inaugurated in its broadest scope, as we hope, it would be a mistake to begin the execution of the plans until the general control and direction can be arranged in a manner to command the confidence of the astronomical world, as well as that of the Trustees. In some respects, however, the situation would be peculiar. In the ordinary case one of the most important functions of the directof of an observatory is the control which he exercises in the choice or work and methods. In the present case the director would be partly shorn of this privilege at the outset, since the very idea of the pro- posed observatory would be the performance of certain definite tasks. Furthermore, in the selection of the staff for the execution of the full program it would be necessary to select, in addition to routine assistants, about twenty astronomers and assistant astronomers of proved capacity and experience in varying degrees. Other qualifi- cations, such as health, energy, and capacity of adaptation to new 48 CARNEGIE INSTITUTION surroundings, would have to be considered in an unusual degree To recruit this staff all at once, for temporary service, from the existing forces of astronomy might prove to be a somewhat difficult task. In case this project should be adopted, therefore, the Insti- tution should be prepared for a somewhat gradual organization of the observatory, expending possibly over four or five years, before all its departments should come into full action. This delay, however, might prove unavoidable from another point of view. The necessary provision for instruments and for their proper installation on so large a scale is a matter which cannot suit- ably be disposed of all at once. In the light of previous experience it may be estimated that a period of three or four years, at least, would be necessary before the means for observation could be pre- pared in all its details. The Southern Ohservatory as an Expedition. An important part of the astronomical work of the southern hemi- sphere has been the result of special expeditious. There are the early expeditions of Halley and I*a Caille and the later ones of Sir John Herschel to the Cape of Good Hope ; of Johnson to the island of St. Helena ; of McClean to the Cape of Good Hope for astro- physical work, and of others. The expedition of Captain Gillis to Santiago de Chile in i85o-'53 resulted in several extensive series of astronomical observations. The establishment of the Argentine National Observatory originated in what was essentially an astro- nomical expedition of the most fruitful character under the conduct of Dr. B. A. Gould. The extremely valuable work of Stone at the Cape of Good Hope was also virtually that of an expedition for a particular purpose. Nearly all the other astronomers who have done highly valuable work in the southern hemisphere have been northern astronomers who went to southern stations for some special work. The idea of a temporary observing station in the southern hemi- sphere will not, therefore, seem to be in any way strange. In one respect it embodies an extremely economical principle — the observa- tory would be maintained only for the accomplishment of works deemed highly important. There would be no chance for it to pass through stages of comparative inaction or to engage in work which is comparatively less pressing, or in undertakings equally well done elsewhere. These are the dangers that may threaten a permanent institution. REPORT OF COMMITTEE ON OBSERVATORIES 49 Furthermore, the duties of administration would be somewhat simplified. It would chiefly be necessary to provide the means for ascertaining whether the works adopted are pushed with the requisite energy and skill — whether the product is that which was stipulated. Pushing this idea to an extreme, the work of the observatory would virtually consist of a series of expeditions having scarcely any connection one with another, except that of proximity at the scene of operations. As fast as the preparations for one of these lines of work should be complete, the expedition for that would be despatched upon its mission, with its own head and its own staff. The larger the establishment, the more necessary it would be to provide a strong observatory organization. All these questions can be more effectively studied after it becomes known upon what scale the enterprise can be carried out. III. Observatory for Solar Research. As the central body of the solar system, confining the planets in their orbits by the power of its attraction and supplying them with light and heat through its radiation, the sun possesses for us an interest greater than that of any other celestial body. From one point of view this interest may be considered to be of a most prac- tical character, since the conditions of terrestrial life are determined exclusively by the solar radiation, so that any possible changes which this radiation may undergo are likely to be of consequence to life upon the earth. From another standpoint the study of the sun possesses a philosophical interest of the highest kind, for the sun is a star, comparable in all particulars with countless stars which lie beyond the boundaries of the solar system, but possessing the unique distinction, through its proximity to the earth, of being susceptible of detailed study and investigation. Thus in all reason- ing on the physical constitution of the stars, especially in connection with the great problem of stellar evolution, we must start from the sun as a type object and elucidate stellar phenomena from an inti- mate acquaintance with solar phenomena. We have no foundation for the hope that any other star will ever appear larger than a microscopic point of light, even though the telescopes of the future may completely outrank the instruments of the present day ; but through the provision of more adequate means of studying the sun 50 CARNEGIE INSTITUTION we may hope immeasurably to strengthen and deepen the founda- tions on which investigations of stellar phenomena are laid. Conversely the only means of studying the origin and develop- ment of the sun and of determining what it will become in the future is afforded by the phenomena of stars and nebulae, for we find in the heavens stars in all stages of growth, illustrating every step in the process of evolution by which the sun has been devel- oped from a nebula. Solar research should thus begin with the nebulae, proceed with a physical investigation of those celestial objects which represent the earlier stages of stellar growth, culmi- nate in a study of the solar structure and radiation, and conclude with an examination of the red stars, one of which the sun will some day become. The study of the sun, with the inseparably connected question of stellar evolution, thus presents a single great problem, important alike to the philosopher, the astronomer, the physicist, the chemist, the geologist, and indeed to every one inter- ested in the study of nature. Purpose of a Soi,ar Observatory. After full and careful consideration of the recommendations of the Advisory Committee on Astronomy* and an extended examination of the various questions involved, we respectfully recommend the establishment by the Carnegie Institution of a Solar Observatory, so situated and equipped as to permit the accomplishment of three principal objects : (i) To measure the intensity of the solar heat radiation, and to determine whether it varies from perfect constancy during at least one sun spot period of eleven years. In connection with this inves- tigation, to measure the absorption of sunlight in its transmission through the atmosphere of the earth and that of the sun, and also the radiation of different portions of the sun's image, such as spots, faculae, and prominences. (2) To bring to bear upon the solution of solar problems various modern methods of research, principally of a spectroscopic nature, which have not hitherto been applied with adequate facilities. More specifically, to provide for the investigation of various solar phe- nomena with the spectroheliograph, the visual and photographic study, with powerful spectroscopes, of the spectra of the chromo- sphere, sun spots, and for other researches of a similar nature. * Carnegie Institution Year Book No. t, Appendix A, p. 96. REPORT OF COMMITTEE ON OBSERVATORIES 5 1 (3) To provide, through the construction of a large reflecting telescope, for the investigation of various problems of stellar evolu- tion, intimately related to solar work, which existing instruments are inadequate to solve. It will be seen that the investigations here proposed may be grouped in another way, viz., (i) those which relate to the sun's radiation, mainly with reference to its effect upon the earth ; (2) those which relate to the solar constitution, with special reference to the sun as a typical star ; and (3) those which relate to the evolution of stars like the sun from nebulae. There are many important reasons to recommend the establish- ment of a solar observatory by the Carnegie Institution. Up to about the year 1875 a large amount of information regarding the phenomena of the sun's surface had been collected, partly through the utilization of more and more powerful telescopes, and particu- larly through the recent application of the spectroscope. But since that time, for reasons not easily to be explained, comparatively few important advances in the study of these phenomena have been made ; very little advantage has been taken of the great improve- ment in telescopes and in spectroscopes during the intervening quar- ter of a century. No other department of astrophysical research has been equally neglected, and consequently in none is there such an exceptional opportunity for great advances. Only one of the twenty two refracting telescopes [of from 20 inches to 40 inehes aperture is regularly used for work on the sun, and with but two or three exceptions the solar spectroscopes in use are little better than those of a quarter of a century ago. Though such spectroscopes are fairly well adapted for the statistical work in which they are employed, they are wholly incapable of dealing with phenomena easily within reach of such spectroscopes as are used in physical laboratories. Even in the few cases in which important advances in solar investigations have been made, partly through the inven- tion and perfection of new instruments, the means available have generally been inadequate to bring out the full powers of new methods of research, and atmospheric disturbances have always most seriously hampered observation. What is needed is an observ- atory at some suitable mountain site, where atmospheric disturbances are reduced to a minimum ; the development of special forms of telescopes, particularly adapted to solar work, and the complete utilization of the numerous improvements in spectroscopes and other instruments for physical research which have been developed in the 52 CARNEGIE INSTITUTION physical laboratory and require laboratory conditions for their suc- cessful use. No existing organization proposes to do this work under these conditions, and there is no prospect that it will be undertaken unless by the Carnegie Institution. Advantages to be Gained Through Improved Atmospheric Conditions. Up to the present time practically all observations of the sun have been made from the lower regions of the atmosphere. This surrounds the observer in a vast fluctuating mass, which reduces the brightness of the heavenly bodies by nearly one half, and transforms their images, which should be sharp and clearly defined, into boiling and confused objects, in which the delicate details of the originals are almost wholly concealed. At rare moments of comparative calm, glimpses may be had of structure of indescribable delicacy, but if partially revealed for a moment it is instantly swallowed up by dis- turbances in the atmosphere. It is as though the astronomer were forced to make his observations from the bottom of an ocean, whose constant storms are not confined to its surface, but penetrate the utmost depths, churning them into a seething mass, through which all external objects seem vague and ill defined. It is evident that such disturbances in our atmosphere must prevent not only a clear and perfect understanding of the solar structure, but in no less degree an accurate and reliable measure of the intensity of the solar radiation, which will seem to vary with the fluctuations in the atmospheric absorption. A sharp distinction must here be drawn between two very different kinds of disturbances which the atmosphere produces. (i) In the measurement of the sun's heat radiation, to determine whether it varies from year to year, the adsorption of the atmosphere is the principal obstacle. No solar image is required, and local dis- turbances due to irregular refraction are of little consequence. The absorption may evidently be obviated in large part by making obser- vations from the summit of a very high mountain, at a point well above the denser portion of the atmosphere where most of the ab- sorption occurs. (2) The detailed study of the various phenomena of the sun's surface, on the other hand, is impossible without a large and well- defined image, free from disturbances caused by local inequalities of temperature in our atmosphere. Currents of warm and cold air, especially if they are in the neighborhood of the instruments, are fatal to successful work. REPORT OF COMMITTEE ON OBSERVATORIES 53 The absorption of the atmosphere for heat and light radiations depends mainly upon the length of the air path which must be trav- ersed by the rays. At an altitude of 15,000 feet the most fluctuating part of the atmosphere has been left below, and the rare atmosphere above is subject to comparatively little variation in its absorptive power. If, then, an observatory for the study of solar radiation should be established at some such height above the earth's surface, in a region where but little water vapor is present, the difficulties hitherto experienced in the measurement of the solar heat would in large measure disappear. But it by no means follows that such a site would be suitable for that department of solar research which requires a perfectly defined image of the sun. As a matter of fact, the sharpness of definition experienced during the day on mountain tops is frequently much inferior to that which may be found at lower levels. At the summit of Pikes Peak (14,147 feet), for example, although the transparency of the atmosphere is very marked, the sun's image is usually not well defined. The same is true at Mount iEtna (9,650 feet), except in the early morning when the low sun has not yet greatly heated the mountain slopes. At the Lick Observatory, on Mount Hamilton (4,208 feet), the day conditions are better, and are probably similar to those which are found at the Yerkes Observatory (1,100 feet) . Until recently no mountain peak has been known on which the sun could be observed to advantage throughout the day. This is presumably due in large part to the fact that the mountain slopes, if not thoroughly covered with foliage, become greatly heated by the sun's rays, producing ascending columns of warm air, which rise toward the summit and mingle with the cooler currents brought by the wind. Under such circumstances bad definition would be inevitable. At Mount Lowe (5,650 feet) , near Pasadena, California, in a region where the remarkable uniformity of temperature and pressure would lead one to expect good definition, the solar image is frequently disturbed by currents of warm air rising from the un- protected slopes. Separated from Mount Lowe only by the width of a single canyon is Mount Wilson (5,886 feet). This mountain is well covered to the very summit with foliage, and thus stands in marked contrast with many of the mountains in southern California.* In consequence of this fact, all of the advantages to be expected from the exceptional quality of the atmosphere are experienced, without the disadvantages due to warm air rising from the heated *See Professor Hussey's report, Appenuix A. 54 CARNEGIE INSTITUTION slopes of the mountain. It is not surprising, therefore, that the sun's image, as seen from the summit of Mount Wilson, is apparently bet- ter defined than at any other point hitherto tested with a telescope. But for the successful prosecution of solar research another condi- tion must be fulfilled. The phenomena on the sun's surface are constantly changing in form, not only from hour to hour, but from second to second in the violent eruptions which are numerous dur- ing the period of greatest solar activity. In order to study these changing phenomena intelligently, it is necessary that they be kept constantly under observation. In observatories subject to frequent clouds and storms the progress of such solar changes cannot be steadily watched. At some critical moment clouds frequently inter- pose to prevent further work. In an investigation of the solar rota- tion, for example, it is of great importance that the position of a sun spot or a facula be determined day after day without interrup- tion. In actual practice many of the photographs made at existing observatories are rendered almost useless on account of the cloud}7 periods which separate them from other photographs. Mount Wil- son has the unique advantage of combining extraordinary perfec- tion of definition with such freedom from clouds as to permit con- tinuous work for months at a time. Summing up, we may therefore say that, even with existing methods of research, important advances in our knowledge of the sun could be attained by providing for observations ( i ) of the solar heat radiation from some high elevation, and (2) of the phenomena of the sun's surface from a site such as Mount Wilson. In the be- ginning the work should be divided between two sites, but it is prob- able that the higher station could be given up after the relation of the atmospheric absorption at the two stations should become known. During the same period it would also be necessary to provide for simultaneous observations from a third point many thousands of feet below the high station, to measure the absorptive effect of a known atmospheric layer, in order that the total atmospheric absorp- tion may be determined and eliminated. New Types ok Reflecting Telescopes and Their Use in Conjunction with Laboratory Instruments. The exceptional opportunity which exists at the present time for advancing our knowledge of the sun by no means depends solety, however, upon the possibility of eliminating a large part of the dis- turbances due to our atmosphere. Even greater possibilities for REPORT OF COMMITTEE ON OBSERVATORIES 55 advancement lie in the application of new instruments and methods. Of first importance is the development of the telescope, including : (i) its construction in the horizontal form, especially for work re- quiring a large solar image and the use of spectroscopes and other instruments from the physical laboratory ; and (2) its construction as a large, short focus reflector, equatorially mounted in the coude form, and particularly adapted for the photography of nebulae, the investigation of stellar spectra, and the study of the heat radiation of the stars. Astronomical telescopes are of two kinds — refractors and reflec- tors. The former consist essentially of a lens mounted at the upper end of a tube, which is pointed toward the object to be observed. The lens forms, at the lower end of the tube, an image of the object the size of which varies directly with the length of the tube. Reflecting telescopes, on the other hand, consist of a concave mirror, usually of silvered glass, supported at the lower end of a tube which is open at its upper end. The rays from the object fall upon the mirror, which reflects them back and forms an image at the upper end of the tube. By means of an additional mirror this image is reflected out at one side of the tube, where it may be ob- served. In both types of telescopes the tubes are pointed directly at the object under observation, and the apparent motion of the object through the heavens is counteracted by a uniform motion of the telescope, produced by clock work. The development of reflecting telescopes during the first half of the nineteenth century culminated in the great instrument of Lord Rosse, erected in 1845. The crudenessof the mounting of this tele- scope, due to the lack of suitable engineering facilities, rendered it useless, except for such visual observations as could be made in the absence of a driving clock. Partly for this reason the immense advantages of mirrors over lenses were not discovered, and during the latter part of the century attention was concentrated in large measure on the development of refracting telescopes. These ad- vanced rapidly in size, from the 10-inch telescopes of Fraunhofer at the beginning of the century to the 1 5-inch Harvard telescope ( 1 847) , the 36-inch Lick telescope (1888), and, finally (1897), the 40-inch telescope of the Yerkes Observatory. (1) But as equatorial telescopes increase in size, it becomes more and more evident that a limit must be set to development in this direction. The driving clock of the Yerkes telescope must move a mass weighing twenty tons with such precision that the image of 56 CARNEGIE INSTITUTION the sun will remain fixed in the field of view for hours together. Attachments weighing as much as 700 pounds may be carried at the lower end of the tube, but it is out of the question, in spite of the great size and strength of this telescope, to carry the large spectro- scopes of modern times. Through the work of Rowland, whose construction and use of concave and plane gratings has done more than any other one thing to revolutionize spectroscopy, the spectro- scope of the physical laboratory has become an instrument of large proportions and of correspondingly great power. Such an instru- ment may be as much as 40 feet in length, and even if it could be attached to a telescope, the bending of the spectroscope, resulting from its constant changes of position, would render it impossible to obtain sharply defined photographs of spectra. The changes of tem- perature which occur from hour to hour in an open dome, subject to the fluctuations of the outer air, would also interfere with the use of such spectroscopes for photographic work, even if their rigidity were perfect. As a consequence, the solar spectroscopes in use today are in almost every case practically identical with the instruments of a quarter of a century ago. Moreover, many physical instru- ments of recent invention and of extraordinary power are so con- stituted that they cannot be attached to a moving instrument : they must stand absolutely at rest, protected from the most minute dis- turbances, on massive piers, in a constant temperature laboratory. It is evident, therefore, that a telescope for physical work, if it is to be suitable for use with such instruments, must be so constructed as to bring an image of the sun or of a star into a physical laboratory provided with all appliances necessary to protect the delicate instruments from vibrations, from relative flexure of their parts, or, sometimes, from temperature changes of even a few hundredths of a degree, and to meet other requirements demanded in the most refined research. The lack of a suitable horizontal telescope made it necessary for Rowland to confine his spectroscopic observations to the light of the sun as a whole, though the use of his powerful spectroscope for a study of the solar details would have yielded results of the greatest importance. Other requirements of solar work remain to be mentioned. It has been found that a solar image seven inches in diameter offers de- cided advantages over a two inch image. There can be little doubt that with such atmospheric conditions as exist on Mount Wilson solar images of two feet or possibly even three feet in diameter REPORT OF COMMITTEE ON OBSERVATORIES 57 could be advantageously employed at times. The use of such large solar images should immediately permit advances of importance to be made. But it would be wholly impossible to secure such images with a refracting telescope of the ordinary type, for the correspond- ing lengths of the telescope tube would be 215 feet or 322.5 feet, requiring mountings of enormous dimensions, not only excessively costly, but wholly beyond the possibilities of construction. For this reason it is evident that another type of telescope must be em- ployed if such large focal images are to be used. Fortunately it is possible to meet all the demands imposed by the above named conditions. It is only necessary to mount the tele- scope tube horizontally in a north and south direction and reflect the light of the sun into the tube by means of a plane mirror driven by clock-work. This mirror is the only moving part of the entire mechanism. Its small size, as compared with a moving tube hun- dreds of feet in length, not only renders the problem of following the object a simple one, but it eliminates at once the entire question of the enormous cost of the moving tube, the dome, and the great elevating floor which, with an equatorial telescope, would be neces- sary in order to permit the observer to reach the lower end of the tube in all its various positions. Heliostats of various kinds have been used for many years, but until recently no serious attempt has been made to construct a large hori- zontal telescope. The instrument of this type built for the Paris ex- position was never completed, and its design was such that the condi- tions demanded in solar work could not have been met. The recently completed Snow horizontal telescope of the Yerkes Observatory and the horizontal telescope of the Smithsonian Astrophysical Observa- tory represent the type of telescopes here recommended for solar research. The Smithsonian instrument was designed for bolometric work, and it has proved to be admirably adapted for this purpose. The Snow telescope was designed for solar investigations requiring a very sharply defined solar image, and special precautions were taken to secure this result. Such a telescope accomplishes, at very small expense, the purposes already named ; it brings a fixed image of the sun into a laboratory, where it may be observed with large spectroscopes or other apparatus mounted on piers. These instruments demonstrate the possibility of constructing a much larger telescope of the same type, designed especially for solar work and provided with large spectroscopes and spectroheliographs. To be successful such an instrument should be mounted at a consid- 5 58 CARNEGIE INSTITUTION erable height above the ground, at a site like Mount Wilson, where the atmospheric conditions during the day are exceptionally fine. Under such circumstances a sharp and well defined solar image, from two to three feet in diameter, could be obtained, and numerous researches now entirely out of reach could be undertaken with every reason to hope for success. Dr. Elihu Thomson has suggested that any distortion of the mir- rors by the sun's heat can be obviated by making them of fused quartz, since the coefficient of expansion of this substance is almost inappreciable. Since Dr. Thomson has already succeeded in mak- ing small mirrors in this way, we include an item to cover the ex- pense of the necessary experiments, which Dr. Thomson has very kindly volunteered to superintend. (2) In work on the sun, as already remarked, the most important requirement is a large solar image produced by a telescope of great focal length, but in order to trace out the successive stages in the development of stars like the sun, a telescope of a very different type is required. The remarkable opportunities for advance in astronomy which exist at the present time through the possibility of building a large reflecting telescope were outlined in the Year Book of the Carnegie Institution for 1902 (p. 141). The optical parts of the Snow horizontal telescope consist exclusively of mir- rors, and it thus preserves the peculiar advantages of the reflecting telescope ; but for the photography of faint nebulse, and for many other similar researches of fundamental importance in the study of the sun's origin and development, this type of telescope is not well adapted. What is needed is a mirror of the largest possible diam- eter and of short focal length, provided with a heavy and well con- structed equatorial mounting. To give an idea of the immense advantages of an instrument of this kind it may be recalled that with a two foot reflector an expos- ure of 40 minutes suffices to photograph stars that are invisible in the largest refracting telescopes. With longer exposures millions of stars can be photographed with such a reflector, of whose exist- ence the largest refractors could never give any indication. A 5-foot reflecting telescope would collect six times as much light as a 2 -foot, and nearly three times as much as the largest reflector now in use, and would open up certain fields of investigation now entirely closed. It would furnish means of photographing the nebulae which would probably be superior to those offered by any existing telescope. It would also permit the heat radiation of some of the brighter stars REPORT OF COMMITTEE ON OBSERVATORIES 59 to be measured, from which valuable conclusions could be drawn as to their physical nature, and it would furnish the essential means of studying stellar spectra on a larger scale than that afforded by existing instruments. Up to the present time such powerful grating spectroscopes as those of Rowland have not been employed for the study of stellar spectra. As already stated, the spectroscopes are too large to be adapted to equatorial telescopes, and the feeble light of the stars would demand exposures far longer than can be given under present circumstances ; but with a great reflecting telescope, so mounted as to produce the image of a star in a constant temperature labora- tory, there should be no serious difficulty in photographing the spectra of the brightest stars with the most powerful grating spec- troscopes. The exposures might have to be prolonged for several nights in succession, but it would only be necessary during this time to maintain the spectroscope rigidly mounted on fixed piers at a constant temperature. With such photographs of stellar spectra a large number of problems, of great importance in connection with questions of solar physics, could be solved. For example, it would be possible to determine beyond question whether, as is now believed by some investigators, the red stars have on their surface a great number of spots like those of the sun. If the presence of numerous sun spots on these stars could be proved it would follow that as the sun grows colder, and advances toward the condition of the red stars, the spots on its surface will multiply in number. Such a conclusion would have a very important bearing on the problem of the solar constitution. Many other similar questions could be answered, such as those which relate to the relative pressure in solar and stellar atmospheres, the changes in the solar spectrum which will result from decreasing temperature, etc. General Nature of the Principal Problems oe Solar Research. It should be evident from what has been said that improved in- struments and methods of research, employed under atmospheric conditions more favorable than those experienced at existing observ- atories, should render important advances possible. Let us now con- sider briefly some of the principal problems of a solar observatory. The Constitution of the Sun. The problem of the solar constitution, though repeatedly attacked on both observational and theoretical grounds, still remains unsolved. 60 CARNEGIE INSTITUTION In addition to the bolometer, referred to elsewhere, the two prin- cipal instruments employed for this work in conjunction with the telescope are the spectroscope and the spectroheliograph. The former permits the investigation of the nature of the chemical ele- ments in the sun, their physical condition, and their motions in the direction of the earth, while photographs taken with the latter show the distribution of the various elements in the solar atmosphere and on the sun's disk. The two instruments supplement each other most effectively, and can be used to great advantage in connection with the bolometer and other physical apparatus. The sun closely resembles the earth in chemical composition, but differs from it in every other particular. Intense heat, indefinitely greater than that of a Bessemer converter, maintains its substance in a state of vapor. The visible surface of the sun marks the limit where the metallic vapors of the interior, coming into contact with the cold of space, condense into luminous clouds. This surface presents a granular appearance, since the bright clouds form the upper extremities of columns of vapor ascending from the interior, separated by spaces filled with cooler and less luminous vapors. Above the visible clouds columns of uncondensed vapors continue to ascend. Hydrogen, helium, and calcium rise to heights of several thousand miles, and at certain points project from the nearly con- tinuous sea of flame (the chromosphere) in the form of great gase- ous prominences, ranging in altitude from 15,000 to 300,000 miles. At times of greatest solar activity violent eruptions frequentty occur, producing prominences which sometimes rise to a height of nearly 300,000 miles in less than half an hour. Formerly the flames of the chromosphere and prominences were visible only at the sun's circumference, when at times of total eclipse the dark body of the moon intervened to cut off the over- powering illumination of the earth's atmosphere. In 1868 it was found that they could be observed in full sunlight with the spectro- scope, and in 1892 they were first successfully photographed with the spectroheliograph. This instrument also permits the flames to be photographed in projection against the sun's disk, thus render- ing possible the investigation of a great variety of new and remark- able phenomena. The invisible vapors of calcium, and recently, through the application of the Rumford spectroheliograph of the Yerkes Observatory, those of hydrogen, iron, magnesium, or any other substance present in the chromosphere, can be photographed at will, and their forms, distribution, and motions investigated. REPORT OF COMMITTEE ON OBSERVATORIES 6l The peculiar differences in the behavior of the various elements and the characteristic parts they play in solar storms suggest questions which are quite as important to the chemist or the physicist as to the astronomer. The high temperature and the enormous masses of material involved in these solar phenomena far surpass the possi- bilities of laboratory experiments. If the elements can be broken up into simpler forms by intense heat, as the tendency of modern research seems to indicate, the best chance of detecting evidence of such dissociation would appear to be in the sun. If calcium, for example, can be separated by heat into several constituents, these can be photographed with the spectroheliograph in solar storms, where their difference in behavior should betray their separate ex- istence. Results already obtained at the Yerkes Observatory point to interesting possibilities in this direction ; but, in order to deal with the problem successfully, apparatus much more powerful than that now employed must be available for use under superior atmos- pheric conditions. Problems without number relating to the solar constitution are ready for solution and demand only a carefully planned attack under suitable conditions. The peculiarities of the solar rotation, rapid at the equator and decreasing toward the poles, have been but little studied. The distribution of the elements in the lower chromo- sphere and the explanation of the absorption which produces the dark lines of the solar spectrum have been subjects of dispute for many years. This problem is now studied only at eclipses, but a large solar image, observed on any clear day with a powerful spec- troscope in a good atmosphere, would permit important advances to be made. The true cause of the darkness of sun spots is not yet understood, and it is even uncertain whether they are cavities or elevated regions. Their minute structure and the remarkable phenomena of their chemical composition will afford indefinite opportunity for research. All of these questions and many others are closely dependent upon the sun spot period. As the spots increase in number and activity all other solar phenomena vary in sympathy with them, increasing to- ward the period of greatest intensity and then fading away toward the time of calm. The investigation should therefore extend over a term of at least eleven years, and preferably until after the maximum which occurs about 1916. The advisability of continuing the work longer may be left to be determined in the light of the results ob- tained. 62 CARNEGIE INSTITUTION The Heat Radiation of the Sun. The advantages of studying the heat radiation of the sun at high altitudes are well illustrated by the results obtained by Langley from the summit of Mount Whitney in 1881. The dryness and purity of the air at this elevation in the Sierra Nevada are perhaps unsurpassed at any other mountain station. Over one half of the atmosphere lies below the summit of the peak, and this comprises the denser and more variable strata, which interfere most with determinations of solar radiation. No sooner had Langley' s deli- cate apparatus been set at work than a new class of solar rays previously unknown was discovered. Previous estimates of the absorptive effect of the lower regions of the atmosphere were found to be far below the truth, and the value of the solar constant, which measures the amount of heat received by the earth from the sun, was immediately increased by about one half. The new radiations which were found to possess so great importance cannot pass through glass, and prisms of rock salt must be employed in studying them. The Mount Whitney observations extended over only a few weeks, and were made with apparatus which, from his present point of view, Professor Langley would consider extremely imperfect. In spite of the unfavorable conditions that prevail at Washington, Langley has continued his investigations at the Smithsonian Insti- tution and developed his methods to an extraordinary degree of perfection. Slow and inaccurate observations with insensitive in- struments have given place to automatic records of the highest precision, secured by the aid of photography with instruments so sensitive that differences of temperature of less than one ten-mil- lionth of a degree centigrade can be detected. The problems which should be attacked from the summit of Mount Whitney, or some equally good station, with the refined instruments now available, cover a wide range. The most important single ques- tion concerns the intensity of the solar radiation. Is this constant, or does it vary during that well defined period of about eleven years in which solar phenomena are known to pass from a state of com- parative calm to one of violent activity, and then again to subside to their former condition? At times of sun spot minimum the sun's surface for months together is wholly devoid of spots. Faculse and prominences are few and inconspicuous, and the spectroscope shows little, if any, evidence of disturbances of any kind. Gradually, however, spots begin to appear, and then rapidly multiply in number. REPORT OF COMMITTEE ON OBSERVATORIES 63 The sea of flame which surrounds the sun increases in brilliancy and activity. As the spots continue to increase in number and area, eruptive phenomena on a tremendous scale become more and more frequent. At the time of maximum activity the violence of these disturbances and the rapidity with which flames hundreds of thou- sands of miles in height form and disappear surpass all comprehen- sion. In view of these facts it is not surprising that the question has been raised whether the total radiation of the sun does not undergo variations corresponding in some measure with these vari- ations in the violence of the phenomena visible on its surface. The solution of this problem, as has already been pointed out, requires that observations be made under conditions not now avail- able. With instruments of the modern type installed at a great altitude and with similar instruments at a second station some thou- sands of feet below, the principal conditions needed for the solution of this question would be provided ; for it is necessary not only to measure the intensity of the sun's heat from an elevation so great as to eliminate most of the obstacles interposed by the denser and more fluctuating portions of the earth's atmosphere, but also to arrive at a more thorough understanding of the absorption which solar rays undergo in passing through our atmosphere, and particularly to determine the difference in the quality and degree of this absorption at different levels. The study of the earth's atmosphere is of great importance in connection with this research. Indeed, it is not improbable that after the completion of a thorough investigation, carried on simultaneously at the upper and lower stations and ex- tending over a sufficient period of time, it would be possible to accomplish all of the purposes of a solar observatory at a lower station. When observed in the telescope the sun's disk is found to be much more brilliant at the center than near the circumference The differ- ence is so great that it was detected in the earliest observations of the sun, made with the imperfect instruments of the time of Galileo. This difference is due to an absorbing atmosphere which completely surrounds the sun, and reduces the intensity of the light and heat radiated outward through it. In a study of this absorption made by Vogel in 1877 it was found that at the edge of the sun's disk only about 13 per cent of the violet rays escape. The percentage of transmitted light increases progressively for the blue, green, and yellow rays, until it amounts to 30 per cent for the red. From these results it has been concluded that if the absorbing atmosphere were 64 CARNEGIE INSTITUTION removed the intensity of the sun's light would increase by as much as i}i times for the red rays to 2^ times for the violet rays. Under such circumstances the color of the sun would appear blue. Later results indicate that the removal of the sun's atmosphere would in- crease its radiation of heat about 1.7 times. It is evident that if there were any considerable variation in the absorptive power of the sun's atmosphere, due to such changes as might easily take place during the passage from minimum to maximum solar activity, the total radiation of solar heat might be very appreciably increased or diminished. Indeed, such a variation in the solar absorption is con- sidered by Halm, in his recent memoir on the solar constitution, to be the cause of the eleven year sun spot period. It is therefore evi- dent that the plan of observations should include an investigation of the heat radiation of various parts of the sun's disk, carried on during a term of years. Evolution of the Sun and Stars. We have already called attention to the fact that while telescopic observations may give us an intimate acquaintance with the sun's surface phenomena, from which conclusions may be drawn as to its physical constitution, they can give us no direct information as to the past or the future of the sun. We must seek such informa- tion in the stars and nebulae. Keeler's work with the Crossley re- flector of the Lick Observatory brought out the extraordinary fact that there are in the heavens at least 100,000 nebulas, the majority of which are of spiral form. It is the belief of many astronomers that this spiral form is indicative of a process of development, and that the teachings of the nebular hypothesis must be modified so as to accord with this new point of view. Advantage should be taken of every possible increase in the scale of the photographs by which the forms of spiral nebulae are recorded, in order that further data may be obtained that may be of service in future attempts to modify the nebular hypothesis. Photographs taken with all possible in- strumental refinements might well be expected to show changes in the nebulae after the lapse of a comparatively short period of time. While we may thus seek in the nebulae for evidences of the sun's origin, its early life and subsequent development may be traced in the stars ; for, in spite of their enormous distance from the earth and the consequent impossibility of observing their surface phe- nomena as we do those of the sun, the spectroscope is competent to REPORT OF COMMITTEE ON OBSERVATORIES 65 give reliable information as to their physical condition and state of development. The secular changes of any star are so slow that thousands of years might be required to detect them. But it fortu- nately happens that all stages of growth are now represented. It is as though one were to pass through an oak forest and seek to learn of the development of the trees. During the period of his stay no apparent change would occur. But he would have before him trees of the same species in every stage of growth : the acorn, the sapling, the oak in its prime, and the dying tree, representing the last stage in the evolutional process. By observing these, the evolu- tion of a single tree could be understood. Thus in the stars, while their changes are too slow to be observed, a similar opportunity exists of tracing their life history. Preceding the condition of the sun we find stars like many of those in the constellation Orion, which have advanced but little beyond the state of nebulae. Next to these come white stars like Sirius, which are but slightly con- densed, and represent what the sun must have been millions of years ago. From these it is possible to pass by gradual steps through the process of development which leads to the production of yellow stars like the sun. Here the process of decline has apparently set in, and the beginnings of the last stage are faintly visible. Finally come the orange and red stars, the spectra of which reveal phe- nomena of the greatest interest, such as the sun will exhibit after the lapse of many centuries. Existing instruments have sufficed to develop the main lines in this process of evolution, but there are numberless questions which cannot be answered without the aid of much more powerful tele- scopes. A great reflector, such as would be most suitable for photo- graphing the nebulae, would also be much superior to any existing telescope for the spectroscopic investigations which furnish the data required in this research. Reference has already been made to the possible existence of great sun spots on the red stars ; these and many similar questions of equal importance in connection with the constitution of the sun cannot be solved until such instrumental means have been provided. Throughout all of this work, both on the sun and the stars, it would be necessary to have constant recourse to laboratory experi- ments in order to interpret the observed phenomena. A suitable equipment of physical apparatus for this purpose is therefore essen- tial in connection with a solar observatory. 66 CARNEGIE INSTITUTION Plans and Estimate of Cost. As already explained, a principal station and two temporary aux- iliary stations will be needed for the proposed Solar Observatory. We recommend that the principal station (A) be established at some such point as Mount Wilson, where Professor Hussey's observations have shown that the conditions are excellent for work on the sun requiring very perfect definition of the image. For the study of the solar constant and the absorption of the earth's atmosphere two auxiliary stations (B and C) will be required for use during the summer months. Station B should occupy a site at the summit of a high mountain, while station C should be near the base of the mountain, some thousands of feet below. In view of the time and expense required, Professor Hussey's study of mountain sites did not include the very high mountains. We have obtained much valuable information regarding conditions on Mount Whitney and other mountains, but a further study of the matter would be required before the sites for stations B and C could be decided upon. While Mount Wilson would probabty serve the purposes of the principal station, there should nevertheless be a further and more prolonged study of sites for this purpose, to be made while the equipment is under construction. Recent experience indicates a probability that stations B and C might be discontinued after observations have been made at these points for two or three seasons, since it is probable that all the work of the observatory could then be done at such a point as Mount Wilson. Principal Station (A). The summit of Mount Wilson is about 8 miles in an air line from Pasadena. At present it is reached from the base of the mountain by either one of two trails, suitable for pack animals, but not adapted for wagons. One of the first considerations, therefore, would be the problem of providing adequate transportation facilities. This might be done (i) by constructing a wagon road from the foot of the mountain to the top; (2) by constructing an electric railway from Pasadena to the summit of the mountain ; (3) by extending to Mount Wilson the electric railway that now terminates on Mount Lowe. Owners of the property on the summit of Mount Wilson state very positively their conviction that one of the two latter projects would be carried out in case this site were selected. This would naturally be an important consideration in the final decision REPORT OF COMMITTEE ON OBSERVATORIES 67 upon the question of site. Estimates of the cost of construction are based on the assumption that such means of access will be available. Plan of Work. The general plan of work which we believe should be undertaken at this observatory would comprise the following classes of observa- tions. This program is of course subject to such modifications as experience may suggest. (1) Frequent measurement of the solar constant, together with studies on the absorption of the solar atmosphere and the radiation of different portions of the sun's image, such as spots, faculae, and prominences. The principal instruments needed for this research are a 16-inchcoelostat and large spectro-bolometer for the solar con- stant work, and a 30-inch ccelostat, with concave mirror of about 200 feet focal length, for providing a solar image suitable for detailed radiation work. (2) Systematic observations, with large spectroscopes and spectro- heliographs, on such problems as the solar rotation, the structure and nature of sun spots, faculas, etc., and other problems related to the solar constitution. For this work there will be required two 30-inch ccelostats, used in conjunction with objectives and mirrors ranging in focal length from 64 feet to 200 feet ; two large plane grating spectroscopes, having focal lengths of about 21 feet and 42 feet respectively, provided with auxiliary apparatus for work with the spark and arc ; a three-prism spectroheliograph of about 10 inches aperture, and a three-prism spectroheliograph of 8 inches aperture and about 33 feet focal length. In order to secure the best defini- tion of the solar image, the ccelostats should be mounted at a con- siderable height above the ground, and electric fans should be provided for stirring the air by L,angley's method. (3) Astrophysical researches on stars and nebulae with a large reflecting telescope, provided with a three-prism spectrograph, and also with a concave grating spectrograph mounted in a constant temperature laboratory, for use with the reflector arranged as an equatorial coude in photographing stellar spectra with very high dispersion. (4) Laboratory investigations, mainly of a spectroscopic nature, on problems arising in connection with the solar and stellar work. Much of the apparatus provided for this purpose should be mounted and used in connection with the solar spectroscopes. 68 CARNEGIE INSTITUTION Buildings. The buildings for the observatory should be of the simplest con- struction, designed for results, rather than for appearances. A. Spectroscopic and Bolometric Laboratory . — Experience has shown that in order to obtain good definition during the day the instru- ments should be mounted at the greatest practicable height above the ground. In the preliminary design for a separate spectroscopic laboratory, the coelostat piers were accordingly carried up to a height of 40 feet. A sketch was also made for a separate bolometric labo- ratory. Subsequently, from motives of econonty, a combination was made of these two laboratories, wherein provision is made for one 16-inch and two 30-inch ccelostats. The two large coelostats would be used for work requiring an image of the sun — one of them for spectrobolometric observations, the other for work with the solar spectroscope and spectroheliograph. The 16-inch coelostat would be employed for measurement of the solar constant. The spectroscopes and spectroheliographs are mounted on piers so high as to be above the level of the constant temperature house for bolometric work. The piers may be constructed either of steel, "properly ballasted, or of granite, which is found in abundance near the summit of Mount Wilson. The laboratory itself is of wood, supported on steel con- struction, anchored to the rock. In the plans submitted provision is made for mirrors of 200 feet focal length, but it is probable that it would ultimately be desirable to extend the house 100 feet to the north, thus permitting the use of a mirror of 300 feet focal length. The construction of the building is such as to reduce to a minimum the heating of the walls and the consequent currents of warm air. B. Reflector Dome. — For a reflecting telescope of 5-feet aperture, mounted in accordance with the general plan shown in the draw- ing,* a dome of 50 feet internal diameter is required. The walls of the tower are built of thin she et iron, the track for the dome being supported upon columns of steel construction. The sheet iron wall is covered on the outer surface with wooden louvers in order to prevent heating by the sun. South of the telescope pier is a con- stant temperature laboratory, with piers for the concave grating spectroscope. C. Office Bui/ding. — This includes offices and computing rooms for all the members of the staff, together with shops for instrument construction, library, laboratories, photographic rooms, etc., suitably * Not here reproduced. REPORT OF COMMITTEE ON OBSERVATORIES 69 equipped for work. This building might be constructed of wood or possibly of rough fragments of granite. In any event, provision should be made for storing the photographs and other records in a small fire proof room. In view of the isolation of the observatory and the important pur- pose of developing new methods and apparatus in connection with its work, provision has been made in the estimates for a very com- plete equipment of the instrument shop. It is understood that this machinery would be purchased and immediately installed in a shop if the Carnegie Institution were to decide to establish the observa- tory. The tools would therefore be used from the outset in the con- struction of a large part of the equipment. D. Dwellings for Members of Staff, etc. — Simple cottages and bach- elors' quarters should be provided at the observatory site. Other items of expense of a general nature would include a tele- phone line and a line for transmitting electric power to the summit of the mountain, sewer and water systems, etc. Stations B and C, for Solar Observations at High Altitudes and Studibs of Atmospheric Absorption. No recommendation is made at present as to the site of these sta- tions, although it is possible that Mount Whitney and Lone Pine would prove to be suitable. The estimates of expense are based on the assumption that sites similar to these would be selected. The plan of work at these stations would include simultaneous observations for the measurement of the solar constant and the de- termination of the atmospheric absorption. The buildings of the two stations should be alike, except for the addition of a few rooms required at the lower station. They contain, in addition to shelter for the instruments, small dwelling rooms for the four men — two at each station — who would occupy them throughout the summer months. The instrumental equipment of the two stations would be similar, consisting of a 16-inch ccelostat and spectro-bolometer for the solar constant work, together with a small miscellaneous equip- ment of instruments required in connection with this investigation. General items of expense in connection with stations B and C would include means of communication between the stations, simple devices to maintain the constancy of temperature needed for bolo- metric work, provision for water supply and fuel, improvement of trails, shelter for laborers and pack animals, etc. 70 CARNEGIE INSTITUTION Staff. A director, in general charge of all work, with special duties in connection with solar spectroscopy. At Principal Station (A). — Bolornetry : An observer in charge of all bolometric work, with special duties in connection with the spectro-bolometer; an assistant observer at the spectro-bolometer, and four computers. Solar spectroscopy : Two assistant observers, to carry on, with the director, solar spectroscopic work ; two computers at the beginning, with the probability that this number will have to be increased during periods of great solar activity. Stellar spectroscopy : One associate and one assistant observer; one computer, and one night assistant, on duty with the large reflector. In addition, there would be required a secretary-librarian, who would also have charge of the accounts and the purchasing of sup- plies ; a stenographer, an instrument-maker, a skilled machinist, a carpenter, a janitor, and two laborers. At Station B. — One observer, one assistant observer, and a man- of-all-work during the summer months. At Station C. — A staff like that at Station B, with the addition of one instrument maker. Lewis Boss, Chairman. W. W. Campbell. George E. Hale. October 8, 1903. Appendix A to Report of Committee on Observatories report by w. j. hussey on certain possible sites for astronomical work in CALIFORNIA AND ARIZONA Prof. Lewis Boss, Chairman Astronomical Committee, Carnegie Institution. Sir : Acting under your instructions, I left San Jose for southern California on April 16, 1903, to examine into conditions for astro- nomical work in that section, especially with reference to research upon the sun. I was to bear in mind the following requirements : First of all, excellent day seeing ; scarcely second to this, excellent night seeing ; fitness of site for living conditions, accessibility, availability of power, electric or other, either from abundant water sources or from commercial distribution, etc. For the purposes of this survey, a 9-inch achromatic objective, focus 108 inches, was kindly loaned to the Committee by the Alvan Clark and Sons Corporation. The Lick Observatory loaned a War. ner and Swasey micrometer, a declination axis and slow motion by the same makers, a good centrifugal driving clock, and many smaller pieces of apparatus needed in this work. A prism-and-grating spec- troscope was loaned by the Chabot Observatory, and an excellent helioscopic eyepiece was supplied by the Yerkes Observatory. The mounting of the telescope was made in the Lick Observatory instrument shops from my designs. Its general features will be understood from the accompanying photographs.* It was expected that tests in out of the way places would be required, and on this account the mounting was made as light as was consistent with sufficient rigidity, and the parts were so arranged that they could be transported on pack animals over mountain trails. The tube is constructed of aluminum sheets one sixteenth of an inch thick, suit- ably strengthened by end and center castings, etc. Its weight, complete with lens, tail piece, micrometer, and counterweights, is only 88 pounds. The wooden polar axis is provided with steel trunnions which turn in roller bearings. * Not here reproduced. (71) 72 CARNEGIE INSTITUTION The object glass is of excellent quality, and the mounting met the requirements in a satisfactory manner. The equipment had been shipped ahead and was awaiting me in Los Angeles. In accordance with your instructions, I at once arranged for its transfer to Echo mountain, where Professor Larkin very kindly put the resources of the Lowe Observatory at my dis- posal, in order that comparative tests might be made with the Lowe 1 6-inch telescope and my instrument. President H. E. Huntington, of the Pacific Electric Railway Com- pany, through his general manager, Mr. Epes Randolph, extended the courtesies of the Mount Lowe Railroad from Los Angeles dur- ing my stay, thus facilitating the work. Mount Lowe, like its neighbors of the San Gabriel range, rises most abruptly from the Los Angeles plains. One approaches the mountain by a mesa which rises so gradually to the precipitous spurs that he scarcely notices he has left sea level behind. Then a cable incline lifts him suddenly to an altitude of 3,200 feet. At the head of the incline are the power house and other buildings of the electric railroad. Some abandoned chalets stand by the edge of the canyon, whose precipitous eastern walls send back the echoes that give the place its name. Properly, Echo mountain is but a spur of Mount Lowe, which is a vast pile of just such spurs, cul- minating in a round, rocky, desolate summit, at 5,650 feet above the sea. The original intention, it is said, was to place the Lowe Observa- tory on the top of Mount Lowe, but the electric railroad was never completed to the summit, and this plan was not carried out. The present terminus of the road is at Alpine Tavern, \yi miles from the top of the incline and at 1,100 feet greater elevation. The Lowe Observatory is situated at Echo mountain, 3,400 feet above the sea, a short walk above the head of the incline, and by the electric road is within fifty minutes of Pasadena and an hour and twenty minutes of Los Angeles. The mountain rises immediately back of the Observatory, on the north, to an angular altitude of perhaps ten or more degrees, so that there is not a clear horizon in this direction. Toward the northeast, across a canyon, another spur rises to a greater elevation, and here, too, the view is obstructed. In other directions the horizon is clear. The water supply of the Observatory is derived from a spring in one of the canyons a short distance away. A reservoir has been REPORT OF COMMITTEE ON OBSERVATORIES 73 constructed just in front of the Observatory and a few feet below. The water from the spring is piped into this, but not into the Observ- atory, the elevation of the spring being insufficient for this purpose. Judging by surface indications, Mount Lowe as a whole is not well supplied with water. Nevertheless, in its canyons, even well up toward the top, one may find clumps of bay and sycamore trees, and these are known to require a fairly constant supply of water. It is possible, therefore, that by judiciously tunneling in the vicinity of these trees water could be developed in places where none is now visible on the surface except immediately after rains. It soon became apparent that the prevailing level of the fog in the Los Angeles region is higher than that for the corresponding season in the neighborhood of San Francisco. It also happened to be the season of maximum drift, namely, April and May. I was there- fore detained at Echo mountain beyond the time limit first set for my stay, the fog being around or above me fully two thirds of the time. For this and other reasons, the suggestion to make tests at two other stations on Mount Lowe was modified, and only one was chosen. This was Inspiration point, at about 4,500 feet altitude, and accessible from Alpine Tavern. Here fog did not trouble, and tests were soon completed, several runs being made by the electric road down to Lowe Observatory for comparative tests with the 16-inch. On the 13th of May the 9-inch was finally dismounted, and the equipment was packed and sent to Los Angeles for ship- ment to San Diego. My stay at Mount Lowe had shown that an elevation of 2,500 feet would in this section be entirely insufficient to escape the prevailing height of either the fog or the dust. It had also impressed upon me the enormous advantage of quick and ready communication with prosperous communities, such as the electric road made possible with Pasadena and Los Angeles, and of the electric power which that brought to hand for mechanical work. I have spoken of the abruptness of the San Gabriel range. The usual mountain masses, however lofty, have a low altitude compared with the measure of their bases. Perhaps an average proportion in the California coast ranges would be that a mountain with an alti- tude of 1 mile would run a base line 15 miles to reach the last of its foothills. Mount Lowe has no foothills, and falls to the mesa's edge in 2^ miles. Mount Wilson, adjacent on the east, higher and broader, holds all its southern spurs well within a sweep of 4 miles 6 74 CARNEGIE INSTITUTION from the summit. Their slopes are practically unscalable except De- constructed trails. Where the steepness does not forbid the way, the chaparral everywhere disputes it. This brushwood growth is pecu- liarly characteristic of the semi-arid mountains of southern Califor- nia. Mount Lowe wears this covering of chaparral, but it is no- where luxuriant. The decomposing white granite is inhospitable soil for vegetable growth. The mountain is sterile and forbidding, except in a few of its canyons. The white granite sand, scarcely covered at all with accumulating humus, stares everywhere through the irregular lanes in the chaparral. In many places the faces of the slopes lie almost bare and glitter unpleasantly in the sun. There is little doubt that radiation from the exposed surfaces accounts for the fact that the day seeing both at Echo mountain and at the higher station at Inspiration point averaged lower than the night seeing, which was, on the whole, excellent. The term mesa is used in the Southwest to denote the fringe of detritus washed down from the mountains and sloping away from their bases to the plains, or the mesa may be formed, as in the region about Flagstaff, Arizona, by lava flows from volcanic cones ; but always, if one examines it as a whole, one finds a sloping upland contiguous on the upper side to mountains and on the lower side to plains or valleys. It is in this sense of contiguous sloping uplands that I use the word in this report. My departure from L,os Angeles for the south was somewhat de- layed by the accidental side-tracking of a part of the freight in its shipment down from Echo mountain. In the meantime I made my first trip to Mount Wilson, going up the Sierra Madre trail on the east side, staying over night, and descending the west or Pasadena trail on the second afternoon. Some days previously I had the good fortune to make the acquaintance of Mr. T. P. L,ukens, of the United States Forestry Commission. He has been of the greatest assistance to me in furnishing reliable information respecting the mountains of southern California and northern Arizona. He spoke enthusiastically of Mount Wilson and advised me to see it. The only access to this peak at present is by the trails just mentioned. These are only wide enough for pack animals, burros, or mules, and about four hours is required for the ascent or descent. I had been assured that Mount Wilson was very different from Mount Eowe, though from the valley it has the same grim outlines; but I was quite un- prepared for the actual view of it. Instead of one barren rock, a succession of rolling knolls forms the summit. The canyons con- REPORT OF COMMITTEE ON OBSERVATORIES 75 tain spruce and the ridges are covered with chaparral — a growth of Ceanothus (buckthorn), scrub oak, and other evergreen bushes, so luxuriant, so dense, that passage through it is quite impossible with- out the aid of an ax. This appealed to me at once as an ideal cov- ering, changeless the year around, for the checking of solar radiation. On exploration, Mount Wilson seemed to have in addition these points of advantage: A water supply remarkable for abundance and nearness to the summit; a small peak adjacent to and above the source of this water, somewhat higher than Wilson's peak, which could be utilized for pressure in a water system ; abundance of granite rock, both dark and light, some of it showing excellent cleavage, for building purposes. Absence of wind, as reported by every one acquainted with the place, is evidenced here by the straightness and symmetry of the trees, one apparent exception being the Ponderosa pine, with a great flat crown as if bent under the pressure of storm and wind. Later, I learned from a paragraph in a report of the United States Forestry Commission that the peculiar shape of this tree is a matter of age and habit and not due to local conditions. The live oak is everywhere, both as tree and shrub, and in the canyons maple, alder, sycamore, bay, and cottonwood are found. Of the conifers, the big-coned spruce most abounds, and it is to this and the chaparral that the mountain owes its unbroken slopes of green. In one thing only does Mount L,owe have an advantage, and that is in the possession of an electric road. As to electric power for mechanical and other uses, a line 4 miles in length from Wilson peak would connect with existing systems. An electric railroad could be constructed from Pasadena to the summit of Mount Wilson quite as easily as to the summit of Mount Lowe ; or, as an altern- ative, it would be possible to extend the present railway from Alpine Tavern around Markham and San Gabriel peaks to the summit of Mount Wilson. It is estimated that such an extension would not need to be more than 10 miles in length. On the evening of May 19 I reached San Diego and occupied the following day with business matters and acquiring information con- cerning conditions in the back country, especially as to the routes into the mountains. On the 21st I made an early start for the nearest of these, San Miguel, a peak 2,600 feet high, standing conspicuous and alone about 13 miles in an air line east of the town. The trip was made in a buckboard, as far as there was any 76 CARNEGIE INSTITUTION road, to the foot of the mountain, and then on horseback to the summit. Clouds lowered all the morning and hid the peak during the approach, but I had a clear and excellent view from the summit. I saw a country very different from the Los Angeles plains. It looks like an old land, and has the simple form and coloring that distinguish the arid regions everywhere. Sharp ridges rise ever more numerous back from the sea, but among the rolling dunes occasional peaks stand alone, boulder-strewn and desolate. San Miguel itself is a type of these — treeless from its top to its base. The horses picked their way without difficulty through the scanty chaparral. Most of it stood just to their knees, though now and then a thicket of buckthorn rose to the riders' shoulders. From the summit to the base I looked in vain for any sign of springs or live water-courses, and there was almost no trace of animal life. Here and there in the valleys below shone little reservoirs of water made by damming open streams. Now, at the close of the rainy season, none of these were full. I was told that the great Sweetwater dam, built at a cost of a quarter of a million dollars, has scarcely 10 feet of water behind it. There seems to be no bot- tom to this land, and in a season of ordinary rainfall most of the water sinks out of sight before it gets to these dams. The higher mountains, with their winter snows, are 40 miles away, and fluming is expensive business. Riding back to town I read everywhere the story of the land of little rain. Just for a few miles at the foot of San Miguel a grassy mesa rolls irregularly down, but passes soon into the dunes of cactus and prickly pear which extend to the sea. In the little winding valleys orchards are dead or dying. Along the dry bed of the Sweet- water river pumps are trying to recover enough to save the trees of that district. San Diego is an incorporated city of perhaps 18,000 people. I went to Lakeside a few days later, and the San Miguel experi- ence was in essentials repeated. Occasional orchards thriving, more abandoned, dying, or dead, according as owners have been able or not to hold out through the dry years and pay the high price of water in a drouth. At Lakeside I took the stage for Cuyamaca, a ride of 35^ miles. This region was chosen as the site of my station for the following reasons : My observations in San Diego had led me to believe that in this region, as at Echo mountain, any altitude below 4,000 feet would often be covered by fog at this season. On this account, as well as on account of the apparent lack of water within REPORT OF COMMITTEE ON OBSERVATORIES 77 i ,500 feet of the summit, the establishing of a station on San Miguel seemed inadvisable. Of the higher mountains, Cuyamaca and Pal- omar seemed to promise most, but in San Diego I was able to get little definite information as to the latter. The impression prevailed that it was very inaccessible. Moreover, Cuyamaca was one of the mountains suggested by your Commission as worthy of exploration, and it has, besides, a daily mail stage from Lakeside to the Stone- wall mine at Cuyamaca lake. The latter is at an elevation of about 4,500 feet, and there it seemed most expedient to make my first camp. In San Diego I had received much valuable assistance from Mr. Ford A. Carpenter, local forecast official of the United States Weather Bureau. Through his interest I became acquainted with Mr. M. C. Healion, president of the San Diego Flume Company. This com- pany controls the water from Cuyamaca lake, and has a house there. President Healion very kindly placed a room at my disposal, and his foreman in charge proved a very helpful assistant. Cuyamaca is an Indian word, said to mean " cradle of the rains," and here is the heaviest rainfall in southern California. The lake is 2 miles long and less than 1 mile in width. The three Cuyamaca peaks rise about it — South peak to 6,500 feet, and Middle and North peaks to approximately 6,000 feet. Rattlesnake hill and a low circle of chaparral-covered hills shut off the view of the Colorado desert, whose first sentinel peak, just visible from the middle of the lake, is barely 6 miles distant in an air line, for Cuyamaca drops abruptly on the east. This nearness of the desert augured ill, and indeed the pull between the great oven and the sea kept the winds at work. The telescope was erected on the green slope at the base of Middle peak, near the dam and the west shore of the lake. Grass is abundant here. Forests of oak rise back of the meadows, and above them the fir, the cedar, and the pine, in turn. The sum- mits are forbidding, and their ascent with horses is impracticable unless road or trail has been cut. Up South peak such a road was made a few years ago by the United States Geological Survey, and that ascent is now easy. The view from this summit, supplemented by constant reference to the topographical map prepared by the United States Geological Survey, gave me an excellent idea of the entire surrounding country. To the north lay Palomar, beyond which rose the white cap of Old Baldy in the San Gabriel range, no miles away. Thence the San Bernardino and San Jacinto mountains lead toward Cuyamaca and the connecting ranges that 78 CARNEGIE INSTITUTION drop to the great desert on their eastern slopes. The Laguna moun- tains reach up from Mexico and thrust out a shoulder that just in- tercepts the view of the great Colorado floor stretching east to Yuma. Down to the west and south fall the lesser hills to the sand dunes and the sea, a country all creased and crumpled, arid and brown. Just below Cuyamaca lie Viejas and Elcajon, peaks whose altitudes and situations had appealed to me on the map as promis- ing sites to consider. The field glasses bring them within a mile or two, and I find them, as I feared, exaggerated San Miguels ; Elcajon more precipitous, Viejas more barren, equally treeless, and by all reports equally destitute of springs above their bases. I learned that frosts may occur any month in the year at the lake ; that the thermometer may rise above ioo° in summer and fall below zero in winter ; that the winds blow very nearly all the time, and that the lake dries up in summer. The seeing at Cuyamaca proved to be what one might expect in a region of high winds and rapidly changing temperatures, and all that could be learned by inquiry and inspection failed to indicate anything more promising in this extreme southern end of the state, excepting Palomar only. I had been told that one must return to San Diego, go by rail to Escondido, and thence by stage in order to reach Palomar. But I had looked across to it repeatedly from both North and South Cuya- maca peaks, and had concluded that one should be able to reach it on horseback from Cuyamaca, through Julian and either the Santa Ysabel or San Felipe valley into Warner's Ranch valley, which is at the southeastern base of Palomar. I set out, therefore, on the morning of the 6th of June. As I rounded the lake and turned north- ward I encountered light breezes from the desert. The peculiar subtraction of vital force effected by these desert winds is scarcely to be understood, but it is never to be denied by those who have felt it. After a hard, all day's ride of about 40 miles via Santa Ysabel valley, through canyons, over hills, and across valleys, traversing roads at times remarkable for steepness, I reached Cook's ranch, on a shoulder of Palomar, late in the evening. I made excursions over the mountain on the following day, and the next day returned to Cuyamaca. Nothing prepares one for the surprise of Palomar. There it stands, a hanging garden above the arid lands. Springs of water burst out of the hillsides and cross the roads in rivulets. The road is through forests that a king might covet — oak and cedar and stately REPORT OF COMMITTEE ON OBSERVATORIES 79 fir. A valley where the cattle stand knee deep in grass has on one side a line of hills as desolate as Nevada ; on the other side majestic slopes of pines. Among the possible places for our purposes, a ' ' bench ' ' on Mr. Cook's ranch seemed especially attractive and caused me to consider most carefully the question whether it would be advisable to bring the equipment to Palomar. Your Committee has had in my reports descriptions of this place in some detail, and a balancing of the ad- vantages and disadvantages of this site, the most promising in the San Diego section, as against Mount Wilson, the most promising in the Iyos Angeles region. This bench is situated at the southern edge of the broad, rolling, open space known as Dyche valley. Its contours adapt it admirably for all the requirements of an observa- tory site. Covered as it is with a good stand of maturing grain and fringed with magnificent oaks, its appearance is most inviting. Springs of water are found in nearby knolls above it, and a hundred feet or so below its edge an abundant stream breaks out that is said to run without change the year round. However, with the long California summer, no amount of irrigation could control the wide pasture lands and secure the changeless green surface of Mount Wilson. A few miles to the east, and less than 2,000 feet below, stretches Valle de San Jose, which heats like an oven and leads away toward the desert. The east winds in winter are said to be furious and not infrequent. The summer climate is almost uni- formly pleasant, and the nights are always cool. The school session is a summer one, for snows in winter may block the roads and render them impassable for children. On the days that I was there the sea breeze was perceptible as early, certainly, as six in the morning, and it grew strong by noon. However, the bench I have described seemed especially sheltered by neighboring hills on the northwest and on the east, and its trees showed very little effect of wind. As soon as the sun was down, a decided chill was noticeable, and though the days had been warm, Mr. Cook proceeded, as a matter of course, to build a fire. The dews are heavy here, as at Cuya- maca. These facts were not favorable to one's expectation of the best seeing. The remarkable stillness, the steady temperature, and the evergreen covering of Mount Wilson could not be found on Palomar, though my judgment, from this cursory examination, would lead me to expect steadier atmospheric conditions here than at Cuyamaca. 80 CARNEGIE INSTITUTION There remains one other important factor against Palomar as a site for an observing station — its extreme isolation. Escondido is the nearest town of any pretensions, and that is 35 miles away. There is a road down the western side of the mountain, laid out to be a 10 per cent grade, but constructed steeper in places. A road is contemplated down the southeast end of the mountain, from Mendenhall valley into Valle de San Jose. This has been sur- veyed and, I was informed, the construction ordered. Whether railroads will soon come nearer the mountain's base than they are at present is entirely uncertain. There are enormous disadvantages in the way of developing the country back of San Diego because of its remoteness, its surface configuration, and the insufficiency of water. It seems to me im- probable that the power, the accessibility, the contact with civiliza- tion, and the resources of a city like Los Angeles, which Mount Wilson has at hand, will ever come within reach of Palomar. Moreover, its nearness to the desert and the absence of protecting mountains to shield it from the winds that play between the heated interior and the sea make it far from probable that we should have here the equable conditions required for the highest grade of astro- nomical work. On returning to Cuyamaca I found that the equipment previously packed was already on the way to San Diego. On arriving there I received instructions to return to the Los Angeles region. The equipment was shipped at once to Pasadena and sent by pack train up the Sierra Madre trail to the summit of Wilson peak. At the close of two weeks' tests at this station a week was spent at Flagstaff, Arizona, before returning north, where, by the cour- tesy of Mr. Percival Lowell, the records and instruments of the Lowell Observatory were freely put at my disposal to gain a knowl- edge of the conditions in that section. The 9-inch telescope has been used at the following stations : Mount Hamilton, Echo mountain, and Inspiration point on Mount Lowe, Cuyamaca in San Diego county, and Mount Wilson. The instrument was set up on Mount Hamilton as soon as com- pleted for the purpose of testing the lens and mechanical parts of the mounting. Comparative observations were made with the 9-inch, 12-inch, and 36-inch telescopes. Some observations of the sun were made, but most of the tests consisted of observations of the stars, and particularly of close double stars. REPORT OF COMMITTEE ON OBSERVATORIES 8 1 It is well known that the maximum efficiency of a very large tel- escope can be secured only under excellent atmospheric conditions. It is also true that a large aperture is required for the most critical differentiation of the various qualities of seeing. It may very well happen that what may appear to be very good seeing with a 6-inch telescope will not prove so with an instrument of the largest dimen- sions. Moreover, different kinds of work vary in their require- ments. For example, with a comparatively short photographic telescope no perceptible difference in the results will be found on nights of excellent definition and on those when the seeing is only fairly good. Again, for meridian-circle work the most essential condition is a steady image, and for difficult double-star work there is the additional requirement of fine definition. Even though some classes of work may be carried on very success- fully under circumstances which are not altogether favorable, it is nevertheless true that they would be more easy of accomplishment under excellent conditions ; and it is also true that many important investigations require the highest obtainable efficiency of the most powerful telescopes for their successful prosecution. That site, therefore, which affords excellent seeing the most continuously, and the necessities, conveniences, and comforts of life the most abundantly, will be the best adapted for the needs of a great observatory. For several years I have used the 36-inch and 12-inch telescopes of the Lick Observatory for double-star and other observational work, and on many occasions when working with one instru- ment I have gone to the other in order to make a comparison of the two. Whenever the seeing appears excellent with the large telescope it also appears excellent with the smaller one ; but when it appears only fairly good with the 36-inch there is a tendency to rate it somewhat higher with the 12-inch. As soon as the tests began with the 9-inch it was further noted that there is a very perceptible difference between it and the 12-inch in the same direc- tion. It was my especial object while the instrument was set up at Mount Hamilton to become acquainted with the characteristics of the image formed with the 9-inch under varying conditions, in order that I might properly interpret them and retain as far as possible 36-inch standards of excellence while making the tests in the va- rious localities. To have proceeded in the opposite direction, by capping down the larger instruments to a 9-inch aperture would, in my opinion, have resulted in a lowering of the standard which it is 82 CARNEGIE INSTITUTION eminently desirable to maintain. It is manifestly impossible to give a numerical rating of the seeing which shall indicate its character- istics fully and without ambiguity. Nevertheless, it is convenient to use a number to express one's estimate of the effect of atmos- pheric conditions taken as a whole. The scale which I have used in this way embraces the numbers i to 5, inclusive. The number 5 is used to denote seeing perfect in every way, a standard of excellence that seldom obtains ; 4, excellent seeing with the excellent conditions lasting for considerable intervals ; 3, good seeing, but with the images less sharply defined than indicated by 4, or having such conditions lasting for much shorter intervals ; 2, poor seeing, images unsteady, large, or blurred, yet of such quality that good work of some kinds can be done, but not that requiring fine definition ; 1 , seeing so bad that good work with large instru- ments is out of the question. At IyOwe Observatory the 9-inch telescope was erected on April 23, between the observatory and the reservoir, and was dismounted on May 2. Observations of the sun were made during the forenoon, and tests of seeing at night — till midnight or later. On one fore- noon only was the day .seeing excellent. The first observations were made shortly after 6 a. m. At that time the sun's limb was sharply defined, and the granulations of the surface very clear and distinct. Several groups of sun spots were visible, and much detail could be clearly seen in both umbrae and penumbrse. At the time of the earliest observation the sun's image was remarkably free from passing heat waves, but this condition did not continue throughout the forenoon. The seeing gradually became worse, and by noon it was bad. It was the usual experience here to find the day seeing grow worse as the forenoon advanced, probably owing to radiation from the nearby and but scantily covered slopes of the mountain. The night conditions at L,owe Observatory were on the average very much better than those prevailing during the day. Tests were made on all clear nights. Several were found to be excellent, others good, and only two bad, one of these being the night after leaving Inspiration point, when a violent storm was coming on. In order to familiarize myself with 16-inch telescope conditions, I employed that instrument on parts of five nights in looking for new double stars. On each of these nights tests were made also with the 9-inch telescope. The following pairs, thought to be new, were found: REPORT OF COMMITTEE ON OBSERVATORIES 83 DM + 480 1707 8h49mi6s.3 +48°35/.9 0.9 10 and io, Comp. of 0 2*196 48 1716 853 16.6 +4814.5 0.3 8.5 8.8 50 1605 854 48.1 +5028.6 3.0 9.1 51 1482 8 56 25 .6 + 51 12 .7 0.4 8.8 9.0 50 2174 15 19 25 .3 + 50 2 .2 3 8.2 12 50 2178 15 23 18.8 +5049.7 1 7.3 12 49 2408 15 31 40.2 +49 16.9 0.4 8.2 8.6 51 2030 15 42 21 .5 + 51 14 .3 0.3 8.5 8.5 51 2077 16 15 57.9 +5I54-7 3-o 8-9 51 2105 16 24 22.1 +51 54.1 3 7.3 12 51 2106 16 25 1.2 +51 45.4 4 6.2 13 51 2130 16 40 10.9 +5148.7 % 7.5 7.5 I have not secured measures of these pairs. The first on the list is of special interest on account of its being the companion of a well-known third-magnitude double star, viz., 9 i-TJrsae Majoris, or 0^196. Alpine Tavern is situated among the trees near the head of a canyon. In its immediate vicinity there is no place that commands a clear horizon. A broad trail leads from it to Inspiration point, and narrow trails run up the mountain to the summit. No pack animals are kept at Alpine Tavern, and on this account it was not feasible to take the equipment to the summit of Mount L,owe. The only place within reach of the tavern that seemed suitable for the erection of the telescope was Inspiration point. The first observa- tions were made here on May 7 and the last observations were made May 13, just before the telescope was dismounted. At Inspiration point observations of the sun were made at inter- vals throughout the forenoon and the earlier portions of the after- noon, the first ones usually about 6.30 a. m. It was found that the day seeing here is similar to that at the L' 23, 1903. In answering the questions proposed by you, permit me first to formulate the following propositions : Astronomy, now and in the future, is confronted with the task of attaining in reference to the universe of stars what has already been accomplished for the solar system, namely, a sure knowledge of the space arrangements and of the motions of the bodies therein contained. Furthermore, the duty is imposed upon each generation of astronomers to contribute toward the attainment of that end whatever is possible with existing means. If, now, one reviews what has been already accomplished in this field, it will be seen that the weak point is not the extent and qual- ity of available observations, but the unequal distribution of them upon the two halves south and north of the equator. From this inequality arises a sensible defect in all discussions which have for their subject, not single objects or groups of objects, but the heavens as a whole. Therefore, without any reservation whatever, I agree with you that an attempt should be made to lessen this defect, espe- cially since an effective remedy through increase in the permanent observatories of the southern hemisphere is not otherwise to be expected at present. As to that which concerns the individual propositions set forth by you, I am of opinion that the strengthening of the weight of exact star positions has precedence over all other things. Observa- tions for parallax, velocity in the line of sight, etc., can be secured at any time, whenever the means are at hand, without fear that a marked disadvantage to the development of astronomy would result from such delay. On the other hand, there is one thing that can- not be retrieved through later observations, and that is the ' ' epoch ' ' of a catalogue. Of the catalogue works mentioned in your communication, the extension of the zones of the Astronomische Gesellschaft to the REPORT OF COMMITTEE ON OBSERVATORIES 117 -south pole is, in my eyes, the one most important for the future of astronomy. This assumes in advance, however, that the work designated by you as No. 1, for the brighter stars, should precede. Therefore, I entertain no doubt that proposition No. 1 should have the preference over all the other tasks. [From Director Kustner, of the Royal Observatory, Bonn.] [Translation.] Bonn, July 2j, 1903. I have read your letter of July 8 and the enclosed program of the Committee of the Carnegie Institution with the greatest inter- est, and I hasten to express to you my full and unqualified acqui- escence in the propositions therein contained. The situation is so clear and simple that, in my view, only one answer is possible to the question, " How can astronomy be pro- moted to the best advantage?" namely, through the establishment of an observatory equipped with the best instruments in the most favorable location in the southern hemisphere. The present neglect of the southern sky is felt in the most troublesome manner in all astronomical problems, and many series of observations that have been secured in the northern sky with great care and at great ex- pense cannot be fully employed for the benefit of science because they pertain to only a part of the sphere. The most important con- clusions can be reached only after these have been equally extended over the southern sky, and then only will the finest fruits of astro- nomical investigation begin to ripen. I can but join in approval of the list of works, arranged in a pre- liminary way according to their importance, which is proposed for this Southern Observatory. This list might easily be further in- creased, but practically, at the outset, it may have to be curtailed. I hold point 1 [meridian observation of stars down to the seventh magnitude] as the most important and — because closely related to it — point 4 [observation of all stars down to the ninth magnitude, southward from — 32 °] . The prompt continuation to the south pole of the great undertaking of the Astronomische Gesellschaft, which has already been extended down to — 230 or — 320 is an uncondi- tional necessity. This last quarter of the sky must soon be worked out, if we are not to lose a considerable part of what has been ac- complished in the three quarters already completed. In the continuation of this plan of the Astronomische Gesellschaft 1 18 CARNEGIE INSTITUTION one will naturally profit by the experience which has been gained in the meantime. For example, the personal equation for magnitude should not be simply determined in an incidental way, but directly eliminated. Further, the zero-stars should be observed not merely at the beginning and end of the zones, but they should be regularly distributed throughout the zones, in such a manner that they should be observed at average intervals of about ten minutes. For the next most important works I consider points 2 and 3 to have the preference [point 2, determination of stellar parallax ; point 3, determination of the velocity of stars in the line of sight]. As to the question of choice of a suitable site, I am unfortunately unable to make any definite recommendation. The precision, and consequently the value, of astronomical observations is dependent in so large a measure upon the condition of the atmosphere, that, in the choice of site, regard for the best possible conditions of atmosphere must be the controlling factor, especially when an observing station is to be established for a few years only. If the question turns on the establishment of a permanent observatory, then, by all means, proximity to some center of civilization is also to be considered. Furthermore, I can but agree in the most complete conviction with the proposition for a great astrophysical observatory especially for solar investigation. The only scientifically correct and at the same time practical way to attain the beginnings of knowledge as to the nature of the fixed stars is, in the first place, through most exact investigation of the star nearest to us, the sun, concerning whose constitution so many obscure problems prevail. I hope that the Committee may be successful in making the large resources of the Carnegie Institution useful for astronomical investigation in the manner proposed. [From Director H. Seeliger, of the Royal Observatory , Munich, Presi- dent of the Astronomische Gesellschaft.~\ [Translation.] Munich, August 3, 1903. The establishment of a new observatory in the southern hemi- sphere, with a large provision for instruments, must be regarded as a desideratum for astronomy. The opinions of astronomers will not differ in this respect, and it would be quite unnecessary to prove this in detail, especially since the Statement which you have been good RErORT OF COMMITTEE ON OBSERVATORIES I i<) enough to send me handles the question completely to the point, and exhaustively. The problems that fall to such an observatory arise through the development of modern astronomy, and, indeed, in this Statement they are so fully and clearly enumerated that very little can be added. The main point is to establish the requisite balance between observations made upon the northern and the southern hemisphere, which, hitherto, the few southern observatories could not possibly maintain. Any arrangement, according to their im- portance, of the classes of observations that ought to be made will naturally depend upon the standpoint of the one who renders judg- ment, and therefore I can only say that I hold the order given in the Statement to be essentially sound. On the other hand, one can make good the claim that the astronomer has not only to collect the knowledge which will enable later generations to derive important results, but also that he should especially challenge those problems that will permit general conclusions to be drawn within a time not distant, even though in a fragmentary way only. From this point of view I have for several years expressed the opinion that, though observations of fixed stars made to establish the motions of the heavenly bodies are important beyond doubt (though they will first bear fruit in the distant future), yet obser- vations concerning the present aspect of the starry heavens should not be neglected. This aspect has an independent interest of its own , and from it a valuable result can be drawn at once without waiting for the cooperation of future generations. Accordingly, on account of their bearing upon my own investigations in regard to the space relations of the stellar system, I would like to designate as especially important the following problems for which the cooperation of the observatories in the southern hemisphere is absolutely necessary, since it is possible to make these discussions only upon the basis of observations distributed over the entire sky : (i) Determination of parallaxes, which appears as (2) in the Statement. (2) An investigation of the apparent distribution of the stars in the southern hemisphere, including those of the faintest magnitude that can be observed. The Statement excludes the consideration of new problems, to be sure ; but here we are concerned, not with a new work, but with an old one which has not hitherto received suffi- cient attention, the object of which is to solve the new problems more conclusively and the execution of which would, in effect, estab- lish the solutions upon a sounder basis. A similar work is now 120 CARNEGIE INSTITUTION being carried out for the northern hemisphere at the Munich Observ- atory, though in a very modest way, since the means at its disposal are very limited, and in this connection I would refer to my report in the Vierteljahrschrift of the Astronomische Gesellschaft. (3) Very man}' — indeed, most — of the investigations in stellar astronomy depend upon the establishment of an exact photometric scale of magnitudes. For the northern sky, in this respect, the magnitudes of the stars down to about the eighth magnitude are fairly well established through the labors at Cambridge ( Mass. ) and Potsdam. In this connection is to be noted the demand for fixing by photometric methods the magnitudes of the fainter stars, through a satisfactory choice of objects, evenly distributed, down to the faintest which can be observed. This is still an object to be desired. For the brighter stars in the southern hemisphere an extensive series of observations is available. But undoubted^ this is not free from objection, and we are not in position to establish the distribution of the stars upon the southern sky in combination with that upon the northern hemisphere. The Statement does not propose to take up photometric and photo- graphic works for the present at least. But I think that the works designated under (2) and (3) are those that are now most pressing and, at the same time, those that would be most acceptable. Here, within a few years, if sufficient means exist, we may hope for results that will be of the greatest importance for all time. Of course, one would better observe with the same instrument first at a station in the northern hemisphere, and then from a station in the southern hemisphere, or one would have to choose a place in the neighbor- hood of the equator, and from that point survey the entire sky, which, of course, would not be entirely free from objection. The choice of a place for an observatory I consider to be ex- tremely important. When one reflects what limitations and disad- vantages the climate in our latitudes impose upon all astronomical observations, one can only look with envy upon the astronomer who is permitted to live in a good climate. What a mass of provocations and waste of time is such an astronomer spared ! I take this oppor- tunity to call your attention to the Australian continent, or to Tas- mania, whose wonderful and, at the same time, healthy climate I know from my own experience, though from no more than a resi- dence of a few months. If, in conclusion, I may present an arrangement of the works mentioned in the Statement, according to my opinion of their im- REPORT OF COMMITTEE ON OBSERVATORIES 121 portauce in relation to the views I have expressed in the foregoing, I would arrange them thus : i. Point (2) of the Statement (parallaxes). 2. Point (3) of the Statement (radial motions). 3. Point (1) of the Statement (meridian observations). 4. Point (4) of the Statement (zone observations). Your further arrangement corresponds perfectly to my views. At all events, a great and inestimable gain for astronomy would be realized if your views in reference to a new Southern Observatory should come to fulfillment, and it appears to me that in that event it is not so much a question ivhat important works shall be assigned to the new observatory, but rather that there are in general impor- tant works which it has to accomplish, and that all in the Statement are such I am fully convinced. [From Sir David GUI, Astronomer Royal at the Cape of Good Hopc.~\ Cape of Good Hope, 12th August, 1903. You ask on behalf of your Committee my views on the subject of the most urgent needs of astronomy. There cannot be the slightest doubt that from the highest stand- point what is most urgently required is an increase in the astronom- ical equipment of the southern as compared with the northern hem- isphere, and this is equally true in the departments both of the older astronomj' (astrometry) and astrophysics. There are urgent needs in both of these departments. The rela- tive urgency will vary, in the opinion of many, according as the individual's knowledge or sympathy lies with one department or the other. Astrometry. A, 1. In connection with the older astronomy, I entirely concur that the establishment of an additional meridian circle of the very first class in the southern hemisphere in an ideal observatory for fundamental observations is a first essential. Practically the Cape is the only observatory where really fundamental work is being undertaken, and some independent check or comparison is necessary if only to give assurance of the accuracy of results arrived at. It may be remarked that most of the observatories of the northern hemisphere are defective in the form of covering or observatory for their transit circles and in the means of equalizing the internal with 9 122 CARNEGIE INSTITUTION the external temperature. Therefore, if any transit circle is to be sent to the southern hemisphere, and is to be used before or afterward in the northern hemisphere for the purpose of comparing results, it seould be provided, for both series of observations, with a modern steel observatory having double or triple walls, means of conveying the convection currents away from the observing opening, and of separating the whole observatory into two halves, so that the instru- ment may be used as nearly as possible in the open air. There is a still more important condition which should also be fulfilled, viz., provision of means to avoid personal equations de- pending on magnitude or upon the velocity of the star's motion (i. e., the star's declination). It seems to me that the only system of observing in R. A. which permits this possibility is the Repsold- Struve method, in which a wire is made to travel across the field at nearly the same velocity as the star. The eye piece travels with the wire, so that, if the mechanical conditions are properly realized, the observer, having bisected the star disc with the wire, should view the disc so bisected apparently as if at rest, and be able by simple means to correct any errors of this bisection which he may notice during transit and which may be due to errors of the clock- work, the driving screw, or the original pointing. The drumhead of the screw which causes the slide of the moving wire to travel is provided with contacts which, as the drum rotates, make electric contact with the chronograph circuit, and so record the instants when the pointing on the star would correspond with the particular read- ings of the micrometer head. This method, so far as I am aware, is the only one not liable to personality depending on magnitude or declination, and this, although we have not yet absolute proof, we believe also to be free from personality in observations of the sun and moon. The necessity for provision of reliable azimuth marks and of a clock not liable to diurnal variation of rate is too well known to require further reference. A separate memorandum dealing with some details of the above- mentioned methods will be forwarded. As to a site, I think it would be difficult to find in the southern hemisphere a better one for this purpose than the neighborhood of Bloemfontein. I venture to think that in connection with this plan one or two of the northern observatories should be provided with a better form of observatory or covering for the transit circle. REPORT OF COMMITTEE ON OBSERVATORIES 1 23 A, 2. There are two other problems of the older astronomy which cry out for solution, one of which is a comparatively small affair, the other a very big one, but both are urgent. I refer to the com- pletion of the organization in the southern hemisphere for deter- mining change of latitude (that is the smaller affair) , and to the formation of a parallax Durchmusterung — i. c, determining the parallaxes of all the stars to a certain order of magnitude — (that is the large one). I take the simpler matter first. Mr. Chandler proposes a southern belt of observatories : Lat. Long. Sydney — 330 51' — 1510 2' Cape of Good Hope — 33 56 — 18 5 30 miles south of Santiago — 33 54 + 70 7 It should involve very little trouble and comparatively small ex- pense to establish the necessary organization at Sydney and the Cape, and I venture to think that the Carnegie Institution could not be better advised than to provide at once for the observatory near Santiago, equipped with two observers devoted wholly and solely to determination of the aberration constant and change of latitude. The instrument I would recommend for all the three observatories would be the photographic almucantar and the method used by Cookson (see Monthly Notices, R. A. S., LXi, p. 315). There should be observations of every group of stars in the early evening, the early morning, and near midnight, at all times when opportuni- ties occur. In this way we ought to get an extremely accurate de- termination of all the latitude changes and a powerful determination also of the aberration constant. A, 3. The parallax Durchmusterung is a very much greater un- dertaking, but it is of the supremest interest to science. I do not think it desirable to go beyond magnitude g}4 or perhaps 9 ; even then the taking and measuring of the plates is a very big business and involves a large organization. A telescope of large aperture is not necessary, but considerable focal length is requisite to give the necessary precision of meas- urement. The highest optical perfection should be arrived at, probably a 4-glass objective of 8 or 10 inches aperture and 20 feet focus would be most suitable. I think it very undesirable to employ a ccelostat or any plan involving reflection from a plane mirror, as plane mirrors may be liable to flexure or deformation by tempera- ture changes. 124 CARNEGIE INSTITUTION Kapteyn's method should be adopted, and all the photographs taken at different seasons on the same plate should be exposed at the same hour angle. Although this involves some sacrifice of parallax factor it eliminates many possible sources of systematic error. I would advocate an observatory (that is to say, a telescope and two photographic observers) devoted exclusively to this work* with an office and staff of measurers and computers located else- where, where the services of students and others could be secured, living is less expensive, and facilities for instrumental construction and repair are more accessible than in the southern hemisphere. To complete the work there must of necessity be a corresponding observatory in the northern hemisphere, and to complete the whole work in any reasonable time there should be several such pairs of observatories. To make a beginning, so as to test the accuracy and probable value of the work thoroughly, it would be well to install one observ- atory of the kind in the most favorable situation and to confine the work, say, to four overlaping areas at each alternate hour of R. A. in each zone of 40 in declination and from declination 6o° at each 4 hours of R. A. The results of such a series of pictures, taken and discussed, would lead to results of immense general importance, and would give .some close approximation to the average parallax of stars of different magnitudes and proper motions, and would be an excellent pioneer program to ascertain the weak points of the original arrangements. It would not too greatly increase the pro- gram if plates having for their centers a number of the stars of more remarkable proper motion were added — indeed, perhaps the program might be best begun with these. A, 4. I am hardly disposed to support the plan suggested by you of extending the zones on the plan of the Astroywmischc Gcsellschaft from declination — 32 ° to the south pole. It is a far more accurate and useful plan to select the stars which are best distributed for determining the constants of photographic plates, as has been done at the Cape for declination — 400 to — 520, and then to determine from the photographic plates the places of all required stars — say all stars to the eighth or ninth magnitude. On the Astronomische Gescllschaft plan you get for this purpose an unnecessary number of stars in some parts of the sky and an insuffi- cient number in others. For the zone — 400 to — 520 I found 8,000 stars ample, and they are as uniformly distributed as it is possible to select them. From the coordinates of our plates (and we are REPORT OF COMMITTEE ON OBSERVATORIES 1 25 about to publish zoues — 400 to — 420, the rest following in course of a few years) with the plate constants which will also be pub- lished any computer can construct a catalogue of all stars to the seventh, eighth, ninth, tenth, or eleventh magnitude, as he may see fit. A, 5. The discovery and measurement of close double stars is an important branch of astrometry which is far behind in the southern hemisphere. I have great hopes that ere long a powerful telescope will be erected at Johannesburg for this purpose. Mr. Innes, re- cently my secretary, has been appointed in charge of the observa- tory there. At present his work is officially that of meteorologist, but I have great hopes that, having regard to his proficiency as a double-star observer, his enthusiasm and his power of exciting scien- tific sympathy, and the number of wealthy and large minded resi- dents there, he will ere long be provided with a first class equatorial fitted for research on double stars. Meanwhile I propose to lend him the portable observatory I used at Ascension and a 6-inch equa- torial of my own, which he is to employ in making an independent determination of the magnitudes of a number of stars on each of the C. P. D. plates. But this prospect should in no way interfere with the erection of a second large telescope devoted to the same work, for independent comparison is at least as important in this department as in funda- mental meridian work. I had the satisfaction, when I visited Johannesburg last May, of selecting a site, outside of the town, which I have little hesitation in saying is one of the finest in the world for an observatory. It is nearly 6,000 feet above sea level, the atmospheric conditions seem to be most favorable, and on my recommendation the site, 10 acres in extent, has been secured by the government. So much for astrometry. I agree with you that the provision made under the direction of Pickering at Arequipa and the labors of Roberts and Innes in South Africa sufficiently fulfill the require- ments of photometric research as compared with that class of work in the northern hemisphere, and the work of the Carte du Ciel ap- pears to be provided for. Astrophysics. B, 1. I have no hesitation in saying that what is required is the erection of the largest possible reflecting telescope for exact re- searches on the spectra and motion in the line of sight of the fainter 126 CARNEGIE INSTITUTION stars. What you want is an instrument that will collect the largest possible amount of light from a star within the jaws of a spectro- scope slit. Not only does a reflector provide this on a larger scale than it is possible to attain in a refractor, but it unites the rays of every re- frangibility in one focus. For spectroscopic work a Cassgrain reflector seems the best form to adopt, as the cone of rays, with its smaller angle of convergence to focus, permits use of a comparatively long collimator. The posi- tion of the spectroscope is also convenient, because, having regard to the weight of the speculum, the radius of motion of a spectro- scope near the speculum end must be much smaller than that of one attached near the principal focus of the large mirror, and it is also much more convenient of access in the former than in the latter case. Of course, photographs of nebulae, &c, could be taken in the focus of the principal mirror, but this is a less urgent need than the spectroscopic researches. With the modern ball bearings and electric-motor motions I see no difficulty in conveniently mounting a mirror of 6 or 8 feet diameter. The erection of such an instrument in some very favorable posi- tion is, I think, the next great step that should be taken. We are in a position now, with refined and well studied apparatus, to at- tack the determination of motions in the line of sight of all the brighter stars ; but to get sufficient light to photograph the spectra of the fainter stars under such dispersion as will furnish reliable determination of motion in the line of sight requires a telescope of greater light grasp than I fear we shall ever get from a refracting telescope. For less money than the cost of a 40-inch refractor one could mount a reflecting telescope of twice that aperture — i. e. , of four times the light grasp — that would unite all the rays of light from a star in one focus. I put this so far beyond all other demands of astrophysics that I make no further suggestion, and I do feel that steps should be taken to urge its fulfilment. I believe that Bloemfontein, in the Orange River Colony, would be an ideal site for the erection of such an instrument. REPORT OF COMMITTEE ON OBSERVATORIES 1 27 [From Dr. M. Nyrin, Wirkl. Staatsrath, Pulkova Observatory^ [Translation.] Puekova, August 14, 1903. The proposition for the observation of stars in the southern hemisphere, which you were so kind as to send me, interests me greatly ; so much the more in reference to some points of the program, because we also here have for a long time cherished ideas tending in the same direction. As a small contribution to the reali- zation of these ideas may be considered, the extension of the Pul- kova Fundamental Catalogue to — 300 , now attained by observa- tions in Odessa. By numerous reference stars these observations are intimately joined with the Pulkova system. I send by this mail the program and the list of stars for this combined catalogue. I quite agree with you that the first task for the observing station in the southern hemisphere should be to create a trustworthy funda- mental catalogue from — 200 to the south pole. In this catalogue the Auwers list of 480 stars, extended to the pole, should be in- cluded; but I would add thereto a number of stars, especially in those places where the stars of Auwers' catalogue seem to be brighter than may be desirable for fundamental stars, third magnitude and brighter. In this manner we should obtain a standard list of about 600 stars, in accordance with your proposition. For the observation of the right ascension of these stars it would not be troublesome to find many places qualified for the purpose. With the declination it is doubtless more difficult ; in this regard even the most southern portions of Australia are, as I think, too far from the poles. Besides, the observations made at the most southern observatory, Melbourne, are apparently affected by suspicious anom- alies in refraction. In my judgment, the fundamental declinations should be observed on the continent of South America, as far as possible south of the — 400 parallel, at a station where the ground to south and to north is as nearly similar as possible. Under favorable atmospheric conditions two observers could accomplish in two years a fundamental catalogue of 600 stars with 8 to 10 observations of each. For the great secondary catalogues, which demand a longer time, the observations, in case of need, could be made at another station, and also with another instrument. As the number of fundamental determinations of the southern stars is rather small, the catalogue in question should necessarily 128 CARNEGIE INSTITUTION receive great weight. It is then, according to my opinion, the best economy of time and money to provide the observing station with equipment of the first rank. Your proposition that the same instru- ment should be employed alternately north and south of the equator will help us to eliminate many errors from the star places. Con- cerning the nature of the instrument, I should, for the declinations, in place of the meridian circle, prefer a vertical circle of moderate dimensions — 5-inch aperture. The vertical circle seems to me, for a new observing station, preferable also from this point of view, that the consolidation of the instrumental piers, which for a meridian circle requires a long time, is for the vertical circle of no importance. As corresponding in accuracy to the declinations determined in such manner, the right ascensions should also be observed with a transit instrument. This part of the work could without inconveni- ence be made at another station, at Cordoba, or in Australia. For the observations of the stars of the secondary catalogues, the instrument described by you will certainly do good sendee. I submit these, my ideas, to your judgment, and I should be glad if you find them worthy of any attention. I have delayed the answer of your letter until Dr. Backlund's return from a journey in Germany. {From Director O. Backlund, of the Imperial Observatory , Pidkova.~\ [Translation.] Pulkova, August 20, 1 go j. In order to make my answer to your valued communication more intelligible, I premise the following remarks : Fundamental determinations of star positions stand in the first rank among the chief undertakings of the Pulkova Observatory. To this end W. Struve had the transit and vertical circle con- structed, by means of which the positions of the so called Pulkova " Hauptsterne," 381 in number, have been determined in three series, namely, at the epochs of 1845, 1865, and 1885 (about). In the year 1894, in accordance with a plan by Nyren, the pro- gram of the two instruments was enlarged by Bredichin so that about 1,000 additional stars of the fourth to seventh magnitudes should be determined for the epoch 1900, in general after the same program as for the ' ' Hauptsterne. ' ' This series of observa- tions is now completed. When I undertook the directorship, in REPORT OF COMMITTEE ON OBSERVATORIES 1 29 1895, I endeavored still further to extend the fundamental ob- servations, and accordingly brought about the establishment of a branch observatory at Odessa (north latitude 460) whose task it is to extend the limits of our fundamental observations to — 300 of declination. In accordance with the experience at Pul- kova during the course of sixty years, the transit and vertical circle were selected as the instruments best suited for making these observations. After thorough reflection I decided in favor of dimensions of these instruments smaller than those of the Pulkova instruments. Since stars fainter than seventh magni- tude would not be observed, the aperture of both instruments was fixed at 4 inches and the focal length at 4^ feet. With dimen- sions so small the obse rvations can be made far more conveniently, and with the vertical circle twice as rapidly as with the Pulkova instrument. The observations for a fundamental catalogue of the same extent as that of the Catalogue of the Pulkova ' ' Hauptsterne ' ' were begun on the third of February, 1901, and, so far as the num- ber of observations is concerned, upon the same program as that of Pulkova. The work was completed exactly a year after beginning, while such a series of observations at Pulkova has never been com- pleted hitherto within less than seven years. Of course, this rapidity of work was made possible not alone on account of the more conve- nient instrument, but also on account of the decidedly better climatic conditions. The observations are already reduced, and it proves that their accuracy comes up to that attained at Pulkova. Both at Pulkova and at Odessa Repsold's self registering micrometer is adopted. This autumn the observation of the Pulkova "Haupt- sterne" is to be taken up for the fourth time, and for the epoch 1905. On this occasion the number of stars has been increased to 500. Simultaneously about 200 more southerly stars will be observed at Odessa, so that the resulting catalogue will contain about 700 stars independently determined between the North Pole and — 300 of declination. It will probably be clear, after this circumstantial description of our fundamental observations, that nowhere can the news of the purpose to institute fundamental observations of about 700 funda- mental stars in the southern hemisphere awaken a higher interest than here in Pulkova. Indeed we are permitted to hope, in accord- ance with your grand project, that at no distant time the long desired and absolutely necessary fundamental observations will be extended over the entire sky, to aid in the further development of 130 CARNEGIE INSTITUTION our knowledge of motions in the planetary system and in the stellar field. That the observations, especially those which concern the declina- tions, should be made, if possible, under a southerly latitude of at least — 400, I am in agreement with Nyren. As to that wdiich per- tains to the planning of instruments, in consideration of the high degree of technical skill in the construction of instruments in America, it might appear venturesome to express decided opinions from here. I content myself with calling attention to the experience which we have gained here in Pulkova and in Odessa with the transit and vertical circle as to the determination of right ascension and declina- tion with special instruments. If, in addition to the fundamental determinations, the projected zone observations can also be secured, you will in that w^ay earn the thanks of astronomers for all time. There can be no doubt that the derivation of astronomical con- stants from observations in the southern hemisphere is a thing to be desired. For example, the very discordant values of the aberration constant, which the determinations secured at different observatories have recently shown, prove how necessary classic observations are. Latitude variations demand observations at places separated from one another as widely as possible. In accordance with an agreement with Potsdam, a series of observations for this purpose will be un- dertaken here in Pulkova, and with a zenith telescope of 5 inches aperture. In regard to your remaining questions, so far as I may be per- mitted to judge, they are not less rationally proposed. You will be able to count upon the unanimous approval of the scientific wrorld not less for these than for the others. That the existing arrears in astronomical work in the southern hemisphere is felt as a drag at every step in every investigation now in progress cannot be denied. If on that account the investigation planned by you is realized, then a great drawback will be thereby removed ; but the well known American energy affords a warrant that the carrying out of this plan wrill not be long delayed. A speedy realization of this project means an immense advance in science. REPORT OF COMMITTEE ON OBSERVATORIES 131 [From Director E. Becker, of the University Observatory , Strassburg .] [Translation.] Strassburg, Atigust 23, 1903. I take note of your letter of July 8 with the highest interest, and I fully assent to the opinions therein expressed. It is a fact not to be overlooked, and one originating in the distribution of observa- tories upon the earth, that our knowledge of the southern heavens is very much behind that of the northern hemisphere. So long as this inequality exists we must necessarily relinquish the idea of ob- taining a satisfactory solution of many and indeed the most impor- tant cosmic problems. That this deficiency will be remedied within a time which we can now foresee by the establishment of new gov- ernmental observatories in the southern hemisphere is not to be expected, and an effort must be made — which would be greeted with the greatest joy in case of success — to induce private institu- tions to lend a helping hand. An observatory established in a favorable site, equipped with modern instruments, under skilled and energetic direction, with a staff of experienced observers and practiced computers not too small in number, in my judgment would be able to complete a work which would suffice to fill up the gaps in our knowledge that are now most deplored. What tasks are deserving of the most prominent place on the pro- gram is a question which it is not entirely easy to answer from an objective point of view, and the answer would also depend upon the means that are available. On the whole, I am in sympathy with the arrangement set forth in your statement, and, for my part, would assign the preference to propositions 1, 3, 4, and 5, with- out underestimating the importance of the other tasks. As to 1, it appears to me worthy of consideration, whether upon grounds of economy, the undertaking ought not to be limited to stars of the sixth magnitude, or, in any case, to those of the sixth and one half, and whether the determination of position for stars fainter than the sixth or sixth and one half magnitude should not be assigned to the zone work, which, according to experience, is susceptible of producing very accurate results. 132 CARNEGIE INSTITUTION [from Dr. Ralph Copela?id, Astronomer Royal for Scotland.} Edinburgh, 26th August, 1903. I have read your letter and inclosure of July 8 with deep interest. Regarding the various classes of special observations to be made in the southern hemisphere, included in your statement, it seems to me that classes 1, 4, and 3 are of the greatest immediate importance, and their urgency is probably in the above sequence, the first being the most important. Class 2 I consider of relatively far less immediate interest, seeing that the results arrived at are by no means of the fundamental character of those obtained by classes 1, 4, and 3. Respecting class 1 , it is conceivable that the observations might advantageously be divided into two groups: a, the fundamental determinations of the places of 600 principal stars, together with the essential observations of the sun ; b, the precise observation of the 5,400 remaining stars brighter than the seventh magnitude be- tween — 200 and the south pole. Group a. — Possibly this work could be most satisfactorily accom- plished by using two instruments — a vertical circle and a specially efficient transit instrument. But these instruments, and in particu- lar the cells of the object glasses, should be made of mild steel, which has a coefficient of expansion differing but little from that of glass and much smaller than that of brass, hitherto so largely used in the construction of astronomical instruments of precision. With the lenses held by springs on the plan designed by Fraunhofer, it is probable that they would rest almost absolutely immovable in their cells in all positions of the instrument, and that their minute real movements would be directly related to changes of temperature. For the vertical circle I would suggest the trial of a design that occurred simultaneously to the late Dr. Common and to myself. It consists in placing an object glass at each end of the tube in such manner that the focus of either object glass shall fall absolutely on the outer surface of the other. Spiders' webs are to be replaced by fine lines, engraved or etched on the outer surface of each object- glass (I have seen lines of this kind not appreciably inferior to the finest natural webs). This construction would permit of the " end for end" reversal of the vertical circle, as well as of the ordinary " right and left" reversal, thus eliminating flexure from every de- termination of double zenith distance. I pass over the obvious REPOKT OF COMMITTEE ON OBSERVATORIES 133 details of the light swing-frames with their counterweights carrying the eye piece at each end of the telescope and readily turned aside when not in use. I feel assured that such an instrument in the hands of a skillful observer would yield zenith distances of an accu- racy not yet attained. One of our first opticians assured me that by the use of twin discs of glass and alternate grinding there would be no difficulty in producing the requisite pair of object glasses. The transit instrument should be reversible on every object. It should have a clean drawn cylindrical tube of mild steel, attached in the simplest efficient manner to the middle of the enlarged steel axis through which it passes. This kind of tube was suggested by Sir David Gill in conversation many years ago. The transit to be taken by means of a movable recording wire — say, 10 seconds in each position of the instrument — by the well known method used so largely by Professor Albrecht and his staff in Germany. By this method collimation error and inequality of pivots are at once elim- inated, and, as it seems to me, the troublesome magnitude equation is practically evaded. Moreover, it is certain that the personal equation is confined within extremely narrow limits. As it would be necessary to observe the sun with this instrument, it would prob- ably be desirable to use a reversing eye piece ; but experience would doubtless soon show whether this is desirable or not. Group b. — This work — the precise observation of the 5,400 re- maining stars brighter than the seventh magnitude between — 200 and the south pole — could probably be rapidly and efficiently ac- complished by the use of a meridian circle, which I should like to see made of steel, with the graduations on gold, platinum, or on an alloy of gold and palladium ; but by no means upon silver, which is so liable to tarnish and necessitate risky cleaning. The observations in class 4 are well worth undertaking with the least practicable delay, as they will gain largely in value by every year that elapses after they are once secured. By carefully boxing in the circle of the instrument used and securing an efficient circu- lation of the air confined within the box, it is probable that the accuracy of this class of observations could be measurably increased. Class 2 seems to me to be the least important part of the proposed undertakings, the resulting stellar distances being apparently pecu- liarly mixed up with those of the few available comparison stars. But may we not hope, now that the displacement of the earth's axis of rotation with regard to the observatory can be taken into account, that the fundamental observations of class 5 may begin to indicate 134 CARNEGIE INSTITUTION the annual parallactic displacements of all the nearer stars relative to the bulk of the 600 stars under observation ? In course of time it would then be necessary to take these parallaxes into account in determining the apparent places of the stars affected by them. Class 6 evidently calls urgently for a large refractor of the most perfect kind, used at a station where the definition is of the very best. Possibly this work could be best carried on at the proposed high level astrophysical observatory, although I may mention that at Jamaica, in the end of 1882, I found the definition near the level of the sea exceedingly good on many nights. In that island it would be possible to find a perfectly salubrious station at an elevation of 4,000 to 5,000 feet, and quite probably equally favorable localities could be found in some of the more mountainous South Sea islands. The general sidereal part of your scheme ought, as you say, to be carried out south of latitude — 300 , but in the southern hemisphere the climate increases in severity at relatively moderate distances from the tropics much more rapidly than it does north of the equa- tor ; hence every care should be taken to avoid a site too far to the south. At the same time I most earnestly support your view that no pains should be spared in choosing a thoroughly salubrious cli- mate ; otherwise the most devoted members of the expedition will be just the most likely to fall victims to any error of judgment in this most important matter. In conclusion, I would suggest placing your most important timekeeper in a partial vacuum — say, under nine tenths of the nor- mal local atmospheric pressure. This is easily secured in a cast iron box with a three-quarter-inch glass face resting on a slip of rubber. A ' ' quicksilver sleeve ' ' permits of winding the clock twice in the week. A small syringe removes any slight leakage of air. We have found here that the air in the box must not be dried artifi- cially, or the oil necessary to the clock work will decompose and the clock will stop. A great improvement would be to add an outer case, the air in which, by a simple electric contrivance, could be kept at a uniform temperature slightly in excess of the highest temperature likely to occur naturally. Under these conditions, any well made clock ought to have a rate subject only to very minute changes. REPORT OF COMMITTEE ON OBSERVATORIES 135 {From Dr. IV. H. M. Christie, Astronomer Royal, Gree?iwich.~\ Greenwich, August 29, 1903. 1 fully agree with the Committee that a much larger provision for astronomical observations in the southern hemisphere at the present time is desirable, and that with this object a Southern Observatory of an expeditionary character for definite pieces of work which could be completed within a limited number of years should, if practicable, be established. Taking the special observations regarded as important by the Committee : 1. The proposed fundamental determination of star positions would be of great value. With this should be combined observa- tions of the sun and determination of position of the ecliptic. Observations of the moon, as nearly continuous as possible through- out the lunation, for several years are very much needed for the im- provement of the lunar tables in regard to terms of short period, and these might well be combined with the observations of funda- mental stars. Observations of the planet Mercury are also much wanted. 2 and 3. I fully agree as to the importance of these and the need for making provision for them. 4. This does not seem to me so much needed at the present time. The observation of reference stars for the plates of the astrographic catalogue now being carried out at Cordoba, the Cape, Sydney, and Melbourne largety covers the ground, and though the number of stars is less than on the plan of the Astronomische Gessellschaft, the place of a far greater number will be determined from the photo- graphic plates with an accuracy greater than that of meridian observations. There is, however, a gap in the southern zones for the astro- graphic catalogue, viz., zones — 32 ° to — 400, the plates for which are being taken at the Perth Observatory (West Australia), but with little prospect of their being measured there or of the necessary ref- erence stars being observed. Another zone, — 170 to — 320, under- taken by Montevideo, is in even worse condition, the funds for pro- viding the photographic telescope not having been granted as yet, though promised by the president of Uruguay. In place of 4, I should prefer to substitute the completion of the zones of the astrographic catalogue by the taking and measurement of the plates and the observation of the reference stars for the zones 136 CARNEGIE INSTITUTION not otherwise provided for. This seems to me to be urgently needed, and the work could be completed in a limited number of years. 5 and 6. I quite agree as to the importance of these. 7, I presume, may be considered later. In the matter of location, I would submit that New Zealand and Tasmania should be carefully considered. An observatory estab- lished in New Zealand would have a good chance of being taken up by the government, as in the case of Cordoba, after its specific pieces of work were completed, and it would undoubtedly give a great stimulus to astronomy in the colony. \From Professor J. C. Kapteyn, Director of the Astronomical Labora- tory, Groningen, Holland.] Vries (near Groningen), August j/, igoj. In answer to the valued invitation of your Committee, I will unreservedly state my views, though they may seem somewhat radical on some points. For evident reasons there cannot be the slightest doubt that a southern astronomical observatory can do much more for the pro- motion of astronomy than a northern one. The works falling in the first line for cultivation at such an ob- servatory I consider to be: 1. Determination of stellar parallax. 2. Fundamental determination of right ascension and declination. 3. Determination of radial velocities of the fixed stars. There are, most certainly, several other works which urgently call for execution, but I think the three works mentioned must take precedence of all the others. Moreover the chances of these other works being undertaken elsewhere on a more or less sufficient scale seem to be somewhat better. So, for instance, the extension of the astrographic catalogue from declination — 320 to — 900 in your ' ' confidential statement. ' ' At the Cape the positions of the reference stars for the ' ' Carte du Ciel " have been determined by the meridian circle. This being so, the positions which will be obtained by the measurement of the plates (as soon as they shall have been reduced to right ascension and declination) will make the want of an extension of the astro- graphic catalogue little felt for that zone. It seems but reasonable to hope that the existing southern observ- atories (Cape, Melbourne, Cordoba) will cooperate to furnish the REPORT OF COMMITTEE ON OBSERVATORIES 1 37 same material for the reduction of the remaining parts of the south- ern sky. Therefore, though (with a view to the indefinite time which may still elapse before we get a complete catalogue of right ascension and declination for use from the ' ' Carte du Ciel " ) I would most cordially rejoice in an extension of the astrographic catalogue, I would still place this work in the second rank of the works most urgently demanded at the present moment. However this may be, I will restrict my remarks to the three works mentioned, which are the most important of all. (i) Determination of Parallax Soitth of Declination — 20 °. As, in my view, there is at present no work so urgently demanded for the advancement of astronomy as the determination of parallax on an extensive scale, the equipment of the observatory for this purpose should be as complete as possible ; for instance : a. Two photographic telescopes, say of 40 cm. aperture and 6 meters focal length. They ought to give round images over a field of 20 diameter. b. One telescope of 40 cm. aperture and a focal distance as great as is compatible with rigid mounting. A round field of, say, 80' diameter or even somewhat less will be sufficient. c. One transit instrument of 7 inches opening. d. One heliometer of 7 inches. Regular morning and evening observations demand two observers for each instrument. A small part only of the time of these ob- servers would be taken up by the observations ; the rest would be devoted to the measuring of the plates and the reduction of the observations. To provide such an outfit and such a staff exclusively for the pur- pose of parallax determination may seem extravagant. I do not think so. The need of a better and more solid knowledge of stellar distance is so great that we should stick to some such plan as is involved in the above, even if it appeared that thereby the funds available would be exhausted. If something must be sacri- ficed, I think the instruments c and d could be best dispensed with, as it seems more likely that the observations to be made by these instruments will be taken up elsewhere. The two telescopes a would serve for a photographic Durchmus- terung for parallax. Elsewhere (Publications Astr. Lab. Gronin- gen No. 1, pp. 87-98) I have explained at some length the feasi- bility and desirability of such a plan. 10 138 CARNEGIE INSTITUTION Notwithstanding the reasons adduced (pp. 97 and 98), some as- tronomers still think that we ought to restrict ourselves to the brighter stars and those of considerable proper motion. We may now exclude the former from consideration, because, for obvious reasons, a photographic Durchmusterung will do little for the very brightest stars. They must be treated by instruments c and d, and there will be little difference of opinion as to the desir- ability of investigating as many of these stars as may be possible. The real question thus is : Has the time come to make a com- plete Durchmusterung of parallax for the fainter stars (say 6.0 to 1 0.0) ? Or may we restrict ourselves to stars of sensible proper motion only? It will be a relatively small undertaking to obtain the parallaxes of the 200 stars of greatest proper motion (this is about the number of stars with proper motion exceeding o".6, known at present, a great part of which are bright ones). It seems not too much to expect that these will be observed else- where. In fact, I think the greater part of them have already been measured. For the rest, if necessary, they will be dealt with by the instruments b, c, d. Setting aside also the consideration of these stars, therefore, it remains to answer the question : What are we to do afterwards — after the observing of the 200 stars of greatest proper motion ? The more important part of our aim must be to get a knowledge of the distance of a great part at least of our nearest neighbors in the universe, in order that we may begin by making a study of the laws in their distribution and motions. Now, if from the very beginning we exclude all the stars of which the proper motion at right angles to the visual ray is small (and we virtually do this by confining ourselves to stars of great proper motion), then we may foresee at once that the finding out of any real law in the motions will be impossible. Our aim will be defeated from the very outset. There are other considerations more amply set forth in the paper quoted which must lead to the conclusion that for a study of the construction of the stellar world we cannot escape the necessity of making a Durchmusterung for parallax. It would be a noble task for the observatory to be erected to take the lead in such an under- taking. For a fairly fine climate I estimate that the two telescopes a together would furnish a duplicate set of plates for the whole sky from declination — 200 to declination — 900 in about eight to ten years. REPORT OF COMMITTEE ON OBSERVATORIES 1 39 All the objects found that are suspected to have a fairly large parallax would be taken up by telescope c. They would be further investigated only in those cases in which a first plate confirmed the large parallax. On the plates furnished by this telescope only the principal object, with five or six well chosen comparison stars, would be measured. The work of measuring and reducing would be very moderate, therefore, especially as a reduction with three constants would be sufficient in nearly every case. Instrument c would serve for the parallaxes of the brighter stars (say o — 6) and, together with instrument d, for the further inves- tigation of objects of certainly measurable parallax. The observatory ought further to be fitted out with (say) ten measuring machines. It is very probable that the observers, though their labors at the telescope would take up only a small fraction of their time, will be unable to make the measurement and reductions keep pace with the production of the photographs. It will be nec- essary, therefore, to procure assistance for them. This, however, will be a question of cheap labor. (See P. S.) I have dwelt thus long on the subject because it is practically a new one. On the others I have only a few words to say. (2) Fundamental Deter minatioii of Right Ascension and Decimation. The great importance of a fundamental determination of star positions, with extension of these observations by secondary methods to include every star brighter than the seventh magnitude south of — 200, is evident to any one who has made some study of stellar motion. I feel very warmly for the plan of transporting to the southern hemisphere, for a short term of years, one of the reversible meridian instruments of the northern hemisphere. The observations of a con- siderable number of stars with the same instrument at a northern and at a southern observatory cannot but lead to a material reduc- tion of the influence of systematic instrumental error and error of refraction. It would seem to me that it would be advantageous to make the determinations of right ascension and declination by two separate instruments, a transit (for which the instrument also used for parallaxes may serve) and a vertical circle. Besides other well known reasons, there is this one : If for the determination of decli- nation we bisect the image of a star by the horizontal wire, its 140 CARNEGIE INSTITUTION brightness is very considerably reduced, especially in the case of the somewhat fainter stars. Thereby the personal error depending on brightness must be changed and an element of uncertainty intro- duced into the right ascensions. If I am not mistaken, the effect was found to be quite perceptible in Leiden. As the elimination of systematic error influenced by refraction and flexure is of such paramount importance for our fundamental declinations, I would suggest to supplement the above determina- tions by the determination of some hundreds of fundamental decli- nations by the method explained in Copernicus III, pages 147-182, which make the result absolutely free from both refraction and flexure. * * * (3) Determination of Radial Velocities. I have no suggestions to add to the plan developed in the ' ' con- fidential statement," with which I most cordially agree, as far as I can judge of the matter. P. S. — In regard to the measurement and reduction of the plates for a Parallax Durchmusterung, which might perhaps be considered to put too heavy a strain on a single observatory, I would like to add that no doubt many of the smaller observatories, not too well pro- vided for, would be only too glad to do the work of first class im- portance by measuring and reducing good parallax plates. Under certain conditions the laboratory at Groningen would very willingly undertake the complete work of measuring reduction and description for a duplicate set of plates for a zone of 20 width at least. [From Dr. Arthur Attwcrs, Secretary of the Royal Prussian Academy, Berlin .] [In a private letter to the chairman Dr. Auwers discusses various topics. The following extracts refer to the plan for a proposed observing station in the southern hemisphere.] [Translation.] Greifswald, October 6, 1903. The ' ' confidential statement ' ' enclosed in your letter of July 7 designates the most pressing astronomical tasks to be worked out in the southern hemisphere so fully and, according to my judgment, so much to the point, that I find very little to add thereto; and, fur- thermore, my pressing work has hindered me until now from pre- REPORT OF COMMITTEE ON OBSERVATORIES 141 paring an answer. You wish me to express myself especially in regard to Nos. (1), (2), and (4), and, although belated, I will do this. The most important task that today confronts the southern ob- servatories is, in my judgment, the production of really fundamental determinations for a selected list of stars. Such determinations for the southern hemisphere are still wholly wanting. We are hoping for a series of such within the next few years from Gill, but it is of the highest importance that we shall be in possession of several such determinations, homogeneous and each as a check on the others, and the establishment of a temporary observing station for this purpose would therefore be a timely undertaking. The employment of a meridian circle, which should be used be- fore and afterwards for similar determinations in the northern hemi- sphere and which has proved itself to belong to the first rank of first class instruments, would be wholly worthy of commendation. By this means one would at least, to a great extent, remove one ele- ment of uncertainty, the adopted flexure. It is possible that the advantage from the employment of this device will not be so great as you apparently hope, since the principal source of uncertainty in our declinations arises from the uncertainty of the refractions, in which local anomalies remain, arising partly in the observatory and partly in its surroundings, and which can be rendered less and less harmful in their effects through increase in the number of observ- ing stations. The attempts which have hitherto been made to establish an ab- solute system of declinations through comparison of observations made in opposite hemispheres are founded on the supposition that the refractions on both sides of the zenith are alike, and I doubt whether this supposition is correct for the majority of those ob- servatories upon whose observations we have had to rely up to the present time for the establishment of systems of declination. The correctness of this supposition seems to me especially doubtful in relation to the two southern observatories which, up to the present time, have afforded the most accurate places of the brighter stars. The Cape, as well as Melbourne, observatories have the ocean to the south and a heated continent to the north, and over these different regions there may be very differently arranged masses of air. I consider it, therefore, very important that the new observation sta- tion should not have a similar position, but that it should be either purely insular or purely continental. At the same time, the southern- 142 CARNEGIE INSTITUTION most latitude possible is desirable. Perhaps the southern part of the Argentine Republic offers what is, on the whole, the most practicable compromise (also the possibility of existence for several years). As closely related to the fundamental determinations and as a work to be accomplished with the same instrument it is very desir- able, as you propose, that there should be complete observation of all stars south of — 200 and to the seventh magnitude, inclusive, four times for each star (equally distributed in the two positions of the instrument, and preferably according to the example set by the Pulkova series for 1855, with exchange of objective and ocular). In accomplishing this the period of observation will be scarcely lengthened and a second wTork of the first importance would be pro- duced. Of still greater importance than this second work, attached to No. 1 , is the continuation of the astrographic zones, the proper and speedy observation of all stars down to the ninth magnitude upon the southern sky (No. 4). In Cordoba this work would have been extended beyond — 32 °, but since Dr. Thome has now undertaken a part in the photographic chart it is very desirable that others should undertake the continuation of the zones. For this purpose, in addition to the meridian circle for No. 1 , a second instrument would naturally be required; but I do not see the use of giving to this instrument a construction of the form you have in mind. The ordinary meridian circle is entirely suited for zone observations, and in any half way favorable climate with such an instrument two ob- servers (one at the ocular and the other at the microscopes) could with ease make 10,000 observations annually at less than — 400 of latitude where one has sufficiently long nights at all seasons; two sets of observers could make 20,000 observations annually. No. 2 is also a task of great importance. The determination of the mean distance of the stars of various orders of magnitude is necessary, in order to provide a firm foundation for investigations into the structure of the stellar universe. But it appears to me im- possible to reach this result otherwise than when one investigates the parallax of each single star of the brighter orders of magnitude, together with a sufficient number of the following orders, as far down as the means of measurement will permit. Dr. De Ball has planned such an undertaking and is corresponding in relation to it with others who have heliometers at their disposal — among others with Dr. Elkin. Therefore I will not go into further particulars, and will only remark that it goes without saying that it would be REPORT OF COMMITTEE ON OBSERVATORIES 1 43 of the highest value to secure for this enterprise the cooperation of another southern observatory in addition to that of the Cape, this also to be provided with a 7 or 8-inch heliometer. In my opinion, this is the only instrument with which, up to the present time, one has been able to secure reliable determinations of parallax. *^ »1# p* #^<» *^» »*f» *y+ With these remarks I have desired to express my personal and lively interest in the plans of the Carnegie Institution, for which I wish a speedy and complete fulfilment. I leave to you to com- municate to your fellow members of the Committee so much of this letter as you think best, but otherwise I desire that you will con- sider it a private answer to your communication. **1* st* %±* •!* »4* >l? *T% ^\ *r* ^r* *r* *y> II. CORRESPONDENCE RELATING TO PROPOSED SOLAR OBSERVATORY. Introduction. In January, 1903, a confidential statement regarding a proposed solar observatory was sent by the Secretary of the Committee to a number of astronomers and physicists. This letter stated that the principal purposes of the observatory, as they then appeared to the Committee, would be to investigate (1) the intensity of the solar radiation and its possible changes during a sun spot period ; (2) the problem of the solar constitution, through observations with the spectroscope and other instruments ; and (3) various stellar and nebular problems connected with the evolution of the sun and stars. The necessity of choosing sites especially suited for such work was also pointed out, and the suggestion was made that for the study of the solar constant a high mountain station, with a second station near the base of the mountain, might be required. Suggestions were requested regarding the proposed program of work, the selec- tion of sites, and any other subjects connected with the observatory. In response to this letter the following replies were received : Letters from Correspondents. \from Professor C. A. Young-, Director of the Observatory, Princeton, N. /.] February 7, 1903. Naturally I am very much interested in the question of a special astrophysical observatory. There is no question that the lines of 144 CARNEGIE INSTITUTION research indicated in 3'our "confidential" paper are important and ought to be followed up in some concerted manner ; but I own to some doubt whether it would be best that all that research should be concentrated at any one, two, or even three stations. Coopera- tion between workers widely enough separated to secure nearly con- tinuous observation might be better, unless some locality can be found where observations are practicable all the time, and I know of no such locality, in the United States, at least. Still it is obvious that, given the "ideal" director with adequate means at his dis- posal, there would be great advantages in the concentration, perhaps quite sufficient to overbalance the disadvantages. As regards my experience at Sherman, it did not indicate any advantages as to average aerial conditions over Hanover and Prince- ton, but during my six weeks' stay there (I think it was six weeks) there were two or three magnificent nights, when the conditions were better than I ever saw them here (one night here, perhaps, excepted, or rather a few hours that night). For solar observa- tions, however, the conditions from half an hour after sunrise till 9 or 10 a. m. were fine more than half the time. About 1 1 it usually began to cloud up, and in the afternoon thunder storms were in order till 8 or 9 p. m. , and for some hours afterwTard the air, though very transparent, was very unsteady. The seeing may have been good after midnight, but I did not examine it often, as my work on the sun gave my eyes all I could safely do with them. Of course, my statement as to the behavior of the weather can not safely be taken as applicable to all years and months. It was in the months of July and August, 1872, that my observations were made, and I remember that some of the few residents of Sherman said that the conditions were unusual for those two months on account of the unusual amount of snowfall the preceding winter on the mountains west and south of Sherman ; but from all I can learn I should think there was much more likelihood of finding better average seeing not very far from the sea, as in southern California. I ought to add that undoubtedly an outburst of vigorous solar activity on the sun's limb from August 1 to 6 had a great deal to do with my success in finding new chromosphere lines. During the first three weeks of work I made little headway and was much dis- couraged. When I began to get up and go to work at 5 or 5.30 a. m. things went better, but the days I have mentioned, August 2-5, gave me fully half my harvest. REPORT OF COMMITTEE ON OBSERVATORIES 1 45 [From Professor Henry Crew, Director of the Physical Laboratory of Northzvestern University , Evanston, Illinois J\ February io, 1903. I have not earlier replied to your circular letter of the 30th ultimo for the reason that I have nothing of value to contribute in the way of suggestions. Congratulations are certainly due to the astrophys- ical world on the splendid prospects set before it by the Carnegie Institution. 1 My own experience, my reason, and my reading all lead me to think that you are not likely to put too much emphasis upon the necessity of untying the bundle of sticks before you attempt to break them. By which I mean to say that you are hardly likely to find at any one station the best conditions for undertaking more than one of the three problems which you outline. The best conditions for the solution of any of these questions would seem to me something like the following : 1 . A carefully and intelligently selected site to which an investi- gator might go with confidence. 2. A single, definite, and not too general problem ; at least, a single problem at a time. 3. The selection of two men whose interest and ability in the matter no one doubts. 4. A simple, plain, but adequate material equipment in all except the central and essential instrument, and then make this the most powerful and most efficient in existence. 5. Study the men you put in charge, see that they are comfort- able, but not "too comfortable," and, above all else, see that the conditions (mechanician, etc.) are such that these men's time can all go to the problem in hand. In other words, leave your men "foot free," and then hold them responsible either for results or for difficulties which are certainly insurmountable. 6. Energy without haste ; test men and sites deliberately. Of all the problems which you mention, the most pressing appears to me to be the need of a continuous record of what is going on at the solar surface. Psychologists often find abnormal cases the most instructive. It may be so with solar studies. Next most important appears to me the horizontal telescope of large aperture. I think this deserves a fair trial in the best attainable spot on the globe, both for spectroscopic and for photographic work. 146 CARNEGIE INSTITUTION [From Professor E. F. Nichols, Director of the Physical Laboratory, Dartmouth College, Hanover, N. H.~\ February 12, 1903. Your letter of January 28, concerning plans and projected work for a new national observatory, has been received. The plans for work embodied under the three heads in the letter seem to me ad- mirable, and to include work of the most valuable kind yet to be done in astrophysics. My own work in astrophysics has been very limited, as you know, but the outlook and far reaching extent of the projected work for the new observatory seems to me in its variety to include nearly everything at present worth doing. In particular the conditions required for the most successful meas- urement of the heat radiation of the brighter stars would be a clear and quiet atmosphere for night work, and a large concave mirror of at least 5 feet aperture. The mirror must be so mounted that the beam from the mirror will be reflected in a fixed direction, so that the heat measuring instrument need not be moved in following the star. It is further very desirable, if not absolutely necessary, that the radiometer or other heat measuring instrument may be sur- rounded by constant temperature conditions during observations. The results which might be expected from such an equipment I have already discussed in my paper in the Astrophysical Journal, vol. 13, p. 138. I shall be only too glad to do anything I can to further the plans of your committee, and only wish that any suggestions that I might make could be based on a broader experience in practical astro- physical work. If at any time I can be of use to your committee in any way, I hope you will have no hesitation in calling upon me. [From Sir William Huggins, Tulse Hill Observatory , London.'} February 17, 1903. I am very glad to hear that there is some prospect of establishing new observatories to provide for observations and researches which require special conditions of position or of equipment. The lines of work sketched out in your letter appear to me to be admirably thought out, and indeed so complete from the point of view of the investigations which have the more immediate claims that I do not see that there remains much, or indeed anything, for me to suggest. REPORT OF COMMITTEE) ON OBSERVATORIES 1 47 I think that it is of first importance to have a permanent obser- vatory furnished with a large reflecting telescope and a complete equipment of auxiliary instruments for astrophysical research on some site with the most favorable conditions of atmosphere. If this were near the equator, it would command the richest regions of both hemispheres. I mention this point in case it might not be found possible to build a separate southern observatory. The observatory next in importance, it seems to me, would be one on the top of Mount Whitnej7-, devoted especially to solar work, or chiefly so. I think the photographic method of getting the corona should be tried. Theoretically it is certain of success, if only the atmospheric conditions are but a little better than normal surface ones. I suppose work could only be carried on during the summer, but if the conditions are as good as the altitude would suggest, there is certainly work enough for many years to come. The observatory at the base might be regarded as temporary, and perhaps might be given up when a sufficient number of observations simultaneous with similar observations at the observatory on the top had been made. \From Professor Arthur Schuster, Director of the Physical Laboratory , Owens College, Manchester, England^ February 18, 1903, In answer to your letter of the 28th January : I should, of course, be highly pleased if funds were to become available for the important work sketched out by you. Taking the different points of your let- ter in order : 1. I have recently looked carefully over a good deal of literature concerning solar radiation, and I confess I have not been impressed by the probability that simultaneous observations at high and low altitudes will help us very much. The differences which such observations could show would all be due to the layer of air included between the two levels. On different days the atmospheric condi- tions of that layer may be very different, and yet the atmospheric conditions at greater heights than, say 15,000 or 20,000 feet, might be the same. You would at once have errors introduced, and the observations at the high altitudes might by themselves give you better results than the combination. You must face the fact that it is impossible altogether to eliminate changes in atmospheric condi- 148 CARNEGIE INSTITUTION tions. Supposing that you were to come to the conclusion that the solar constant observed, even at high altitudes, varies with a sun spot period, it would still be open to doubt whether the change is not due to something that happens in the higher layers of the atmos- phere. That, in niy opinion, would be the most probable explana- tion, but as even this fact would be important to establish, I quite agree that observations on the solar constant should be made at fre- quent intervals. Whether there are any actual differences in solar radiations at different times is a question that will, I think, be solved in a different manner. It seems to me exceedingly unlikely that any increase or diminution in solar radiation can take place equally and simultane- ously all over the solar surface. If sun spots have anything to do with it, we must imagine the changes to come out differently or at least at different times in different solar latitudes. I would therefore consider it a matter of first importance to improve observational methods as much as possible, so as to be able to compare with the utmost accuracy different parts of the solar surface in different por- tions of the solar spectrum. A change in temperature of even ioo° ought to make an appreciable difference in the radiation at the violet end, though the radiation in the red will not be affected nearly as much. I have been very much struck with a recent paper by Mr. Wood, of Baltimore, which describes a screen that absorbs the visible light, leaving the ultra-violet. I should say that simultaneous photographs taken of the solar disc by the ordinary method and with this screen might give interesting results. 2. I think you know already the great importance I attach to the careful investigation of the spectrum of sun spots, and the other points you mention are of equal interest. 3. Here again I agree with you that such work as the measure- ment of the heat radiation of stars and investigations of spectra with very high dispersion are bound to lead to important results, and if your present atmospheric conditions at available observatories are not sufficiently good it would no doubt be highly advisable to have a site specially selected for the purpose. I am not, of course, able to judge whether the same site may be suitable for the solar and stellar work, and I do not want to dis- courage altogether the possibility of a station at the base of a moun- tain on which solar observations are taken. Some useful results might be obtained in this way, but I should not hope for very much and should not personally be inclined to recommend any great ex- REPORT OP COMMITTEE ON OBSERVATORIES 1 49 penditure for such a purpose. Possibly a very moderate equipment at the base would do all that is desirable. Might I also mention, in addition to the matters you speak about, that a repetition of Duner's work on solar rotation in the reversing layer is, I think, called for? I do not think the last word has been said in that matter. [From Professor H. C. Vogcl, Director of the Royal Astrophysical Observatory , Potsdam, Germany^ [Translation.] February 19, 1903. In reply to your kind letter of January 15 in regard to the estab- lishment of a great astrophysical observatory with stations at particu- larly favorable points, I wish to reply that I can only commend in the warmest way the realization of this great undertaking in the interests of science, and that I regard the investigations proposed by you, on the subjects named below, as so suitable and exhaustive that I am unable at present to suggest anything further : (1) Solar radiation problems, involving the measurement of the solar constant at frequent intervals throughout the sun spot period. (2) Solar investigations, principally of a spectroscopic nature, which require atmospheric conditions and instrumental facilities superior to those hitherto employed. (3) Various stellar and nebular problems, such as could be under- taken to the best advantage with the aid of a large reflecting tele- scope. In Europe we are not so fortunately situated as to be able to find so easily sites from which the proposed observations could be carried out to advantage. We can therefore only wish success to our Ameri- can colleagues if the Carnegie Institution should provide the means necessary to carry out such comprehensive investigations, which are so important for astrophysics. [From Prof essor H . Kayser, Director of the Physical Institute , University of B 07in> Germany^ [Translation.] February 20, 1903. I am so busy at the end of our semester that I can reply only briefly to your letter of January 30. 150 CARNEGIE INSTITUTION If a new institution, provided with unusual instrumental means, is to be established for the study of the sun, it should have the solu- tion of one especially important and fundamental problem as its principal purpose. The most important question seems to me to be with regard to the constitution of the sun. We seem to be infinitely far from the solution of this question — whether it is wholly gaseous or in part liquid or solid. This question must be solved through a very detailed study of the various parts of the sun. It seems to me particularly important to make a study of the sun spots. If their spectra could be photographed in the greatest possible detail throughout a solar cycle with large gratings, an important advance would probably be made. In this way it might be possible to form a proper estimate of Julius's theory — either to confirm or refute it. This investigation is a rather thankless task, since it consists only in gathering observational material ; but a result drawn from it would be far more important for our knowledge of the heavenly bodies than the measurement of the radial velocity of a few hundred stars or the intensity curves of variables. As soon as the charac- teristic features of our sun are thoroughly understood, many other phenomena will explain themselves. I would advise the use of plain gratings for this investigation, since freedom from astigmatism is necessary ; the lenses should be preferably of quartz-fluorspar, and the solar image on the slit should be of large diameter. Terrestrial spectra must, of course, be employed for the explana- tion of the phenomena. The laboratory must, therefore, be sup- plied with concave gratings of various numbers of lines to the inch and various radii of curvature ; also with direct current for arc lamps and alternating current for transformers, as well as induction coils of various dimensions up to one meter spark length, in order that the spectra of the elements may be studied under the most varied conditions. I have touched upon only a single question, which seems to me to surpass all others in importance. It goes without saying that a large institution would also undertake investigations requiring night observations. I name here briefly only two of investigations which seem to me particularly important : the spectra of the planets, in order to determine the nature of their atmospheres, and the spectra of a number of the brightest stars with a precision approaching as closely as possible that of Rowland's solar spectrum, so that their chemical constitution can be accurately compared, and if differences REPORT OF COMMITTEE ON OBSERVATORIES 151 are found in the spectrum of the same element the cause of these differences may be investigated. I believe that the problems which I have named have hardly re- ceived serious consideration hitherto. All are for the purpose of determining accurately the physical and chemical constitution of at least a few of the heavenly bodies. In the case of the sun itself Rowland's atlas and tables may be regarded as only the first though a most important step toward a knowledge of its chemical constitu- tion. A further study of the spectra of the elements would certainly permit 90 per cent of the lines now designated as unknown to be identified. [From Dr. IV. E. Wilson, Private Observatory , Daramona, Ireland.'] February 24, 1903. I was very glad to receive your letter of January 28 and to see that there is the prospect of founding a large observatory for investiga- tions on solar radiation and kindred subjects. I am sure such re- search can be profitably carried on only in situations such as you propose. Ireland is certainly not one for such work. I have been experimenting for two years with a new recording bolometer, which I think would give excellent results if it were mounted in a situation where it would get some sunshine. This it does not get here. If you would care to have it tried at your new observatory I would be delighted to send it to you. All you would require would be one of Callendar's electric recorders to work with it. It consists of two flat coils of platinum wire blacked and sealed up in an exhausted glass tube. This is enclosed in a brass tube with suitable diaphragm, so that one coil only receives radiation from the sun and a small bit of surrounding sky. The other coil is in the shade. These form the arms of the Wheatstone bridge of the recorder, and it gives a contin- uous record of the radiation. With the form of receiver designed by Callendar the coils were not in vacuum, but merely covered with a glass shade. One coil was black and the other bright, and both lay horizontally, so that the sun was never normal to them, and of course changing from hour to hour. I found that with this old receiver it was quite impossible to calibrate the curve with Angstrom's pyrheli- ometer. Even on a dark, wet day it gave a considerable deflection, by reason of the glare from the clouds. With my new form the curve can be calibrated with the Angstrom instrument perfectly, and by means of a planimeter, which is attached to the pen of the re- 152 CARNEGIE INSTITUTION corder, you can read every day the area of the resulting curve. I enclose you some sample records. Those marked A are taken with the old receiver and B with the new one. You will see that in B when there is no sunshine the curve falls to the zero line. In A it is always above it. I wish you could also see your way to cany on a series of obser- vations by allowing an image of the sun to transit over the aperture of a small radiomicrometer and recording the deflection on a moving photographic plate. By a discussion of the resulting curves I think it would be quite possible to determine whether the depth of the absorbing layer on the sun varies during a sun spot cycle. I began taking curves here, but the weather was so hopelessly unfavorable that I gave it up. [From Sir Norman Lockyer, Solar Physics Observatory, South Ke?i- sington, London.] February 25, 1903. In response to your letter of January 29 regarding the work to be done by a new astrophysical observatory, I would say that your scheme practically covers the whole ground. There are, however, one or two points to which attention might be drawn : 1. Would it be advisable to erect a permanent building on a mountain summit without first putting up a temporary building and making observations from it for a year or two ? 2. It is of great importance that the observatory should not be too far away from some large town easy of access, as modern work requires the investigator to be in touch and personal contact with scientific men for purposes of mutual assistance and advice in addi- tion to the reasons given in your letter. 3. It is important that the laboratory equipment should be com- plete, for it is the mutual work of the observatory and the laboratory which helps the investigation. 4. The Janssen-Hale-Deslandres method of photographing the solar prominences should undoubtedly be undertaken and made strict routine work. I am very glad to see that you mention the photographing of the ultra-violet end of stellar spectra, as this is important and we are at work upon it, although we have very small means here for carrying it on. REPORT OF COMMITTEE ON OBSERVATORIES 1 53 \_From Professor C. E. Mcndcnhall, Physical Laboratory, University oj Wisconsin.] February 27, 1903. Your letter of February 2 came duly to hand, and I haye made a few notes concerning that part of the proposed work with which I am somewhat familiar. These I am very glad to send you now, hoping that the delay has been of no inconvenience to you. I have not thought that you wanted great detail, and have tried to avoid it. Though most if not all of the suggestions are such as must have already occurred to you, I nevertheless give them, thinking that perhaps they may usefully serve to confirm if not to initiate. As regards the general scope of the work, I shall not presume to speak further than to emphasize the importance of one point which you mention, namely, provision for the study of such laboratory problems as seem intimately connected with the solar and stellar work. In deciding upon the site it may be well to keep in mind, besides the primary requisites, the fact that the observatory will demand a constant though small supply of power. Possibly in California some long-distance transmission line or water power could be drawn upon. For the solar constant work examples of all the best forms of pyrheliometers and actinometers should be provided and studied with a view to improvement. No one of them seems independently reliable at present, though the Angstrom compensation pyrhehometer promises best. For detailed infra-red spectroscopic work there is no doubt that the bolometer is the most immediately applicable, because of the work of Abbot and others at the Smithsonian Astrophysical Observ- atory. But the radiometer, thermopile, and radiomicrometer each has its peculiar advantages, so that if they were properly modified for linear spectroscopic work they might be used with advantage at the two substations. It seems to me unlikely that they will ever supplant the bolometer for accurate linear work in cases where the best must be had at any cost. In designing the spectrobolographic outfit it seems to me ques- tionable whether it should be as large as that of the Smithsonian Institution. At any rate, even if one outfit of such size is provided for the main station, it would be desirable to provide another of con- siderably smaller size, more or less self contained and capable of being used with advantage by a single observer. For some of the work n 154 CARNEGIE INSTITUTION this could be used in place of the larger outfit with resulting saving in time and labor, and for much of the preliminary work and for the laboratory investigations it would be decidedly more convenient. A storage battery equipment will be a necessity, small and port- able, for the substations, but of considerable capacity for the main observatory. Especially should this be the case if laboratory work is undertaken, as this will undoubtedly involve the production of high temperatures which can best be done electrically. In this case also accurate means of measuring high temperatures will be necessary and a variety of laboratory sources of radiation should be available. Of course, work would be greatly facilitated by a generous assort- ment of miscellaneous laboratory apparatus, such as small spectro- scopes, telescopes, mirrors, polarizing apparatus, air-pumps, etc., and a lot of laboratory supports and attachments. Finally, as much of a shop equipment as is possible. In connection with the spectrobolographic work, I must confess that at present the further detailed study of the infra-red solar lines does not seem to promise very much. Undoubtedly the true solar lines can be separated from those of terrestrial origin and identified to a greater or less extent with emissions of known elements, and this would perhaps be of most value in connection with the question of the persistence of given emissions through long ranges of tem- perature. Again, if the sun's surface were studied in greater detail the infra-red lines might help in the study of motions in the solar atmosphere, but it does not seem likely that they would be more important for that purpose than the lines photographically observable. Of course, it may be found that the infra-red lines behave in some ways quite differently from those of shorter wave length, and hence furnish a valuable tool for solar investigation, but it does not seem to me that the work so far done leads one to expect this. However, you know much better than I what to expect. Again, is it not true that the solar constant work and the separation of true solar lines from those of terrestrial origin are the parts of the work which really demand the high and low mountain stations, while much, if not all, of the other work, on account of its more intimate connection with laboratory experimentation, could better be carried on at a more centrally located observatory; for example, the Yerkes, best of any. REPORT OF COMMITTEE ON OBSERVATORIES 1 55 [Fro?n Professor A . Riccb, Director of the Royal Observatories of Catania and Etna, Sicily.] [Translation.] February 28, 1903. With regard to the project under consideration by the Committee of the Carnegie Institution, of which you are a member, it is certain that if a station at the summit of a very high mountain is needed for the study of the solar radiation, another station will also be re- quired which may be conducted without encountering the difficulties which are unavoidable at elevated stations ; among others, the fre- quency of days when the mountain is enveloped with clouds due to the condensation which it produces. Etna, for example, as seen from Catania, is enveloped with clouds 167 days in the year, on an average. The other station should not be placed at the foot of the moun- tain, since it would also experience the effect of condensations caused by the mountain. At Catania the clouds cover on an average only 39 per cent of the sky (Palermo, 46 per cent), but this amount of cloudiness would be still smaller if it were not for Etna, since the clouds appear more often on the side toward Etna (north) than else- where. Furthermore, the station at the base of the mountain would not have an entirely free horizon in one direction. There should also be a third station on a very extensive high plateau on a small island, in order to have a very homogeneous atmosphere in perfect equilibrium, and to avoid disturbances of the images caused by ascending currents ; these are very pronounced during the hotter part of the day on Etna, and carry up with them visible vapors, which frequently hide the sun, and invisible vapors which produce remarkable absorption of the solar radiations. On Etna the curves of heat received by the Arago actinometer have this form [figure not reproduced here] . This may be explained by the absorbing action of the ascending vapors during the hours of greatest heat. At Catania the curves have the regular form, rising with the altitude of the sun. At Catania, as at Palermo, the images of the sun are best in the early morning ; ordinarily during the hot seasons they are bad at 10 o'clock ; they become better again before sunset. 156 CARNEGIE INSTITUTION [From Professor A. Bclopolsky, Imperial Observatory, Pulkova, Russia.] [Translation.] March ii, 1903. The project of constructing several astrophysical observatories in the United States is of very great importance. Investigations of the sun are precisely those which require study by modern methods. At the present time, since the discovery which you have made with the spectroheliograph, the study of the solar surface with instru- ments of sufficient size promises to reconstruct current ideas regard- ing the constitution of the sun. The glory of accomplishing this will belong to the United States if the construction of special observa- tories is provided for. It will perhaps be possible to find a mountain more advantageous than Mount Whitney for investigations of the solar radiation. I believe that the station can be established only at a distance of 300 meters below the summit. The plan for the investigations on the constitution and radial motion of stars also requires instruments more powerful than those which are employed at the present time. Everyone desires to undertake such work, but no country can realize this desire, since nowhere are sufficient funds available for scientific researches. It is only in the United States that private fortunes are devoted to science. But, as you are well aware, successful investigators are quite as necessary as instruments. I believe that as many scientific investi- gators as the newly established observatories will need may also be found in America. [From Professor Cleveland Abbe, U.S. Weather Bureau, Washington^ Aprie 3, !903. Your letter of March 25, as Secretary of the Commission relative to the establishment of a large astrophysical observatory, interests me very much. The practical question as to the location and main- tenance demands first consideration. There is no doubt that an observatory at the highest practicable point, working in cooperation with one lower down, will eventually add much to our knowledge of the solar and the terrestrial atmospheres. I consider Mount Whitney the most desirable summit station ; a station at its base is necessary both for supplies and for special work on absorption. Another station in nearly the same meridian but farther south can REPORT OF COMMITTEE ON OBSERVATORIES 1 57 scarcely be found, but in place of that I think that the location of the Flagstaff observatory would be an admirable substitute. Among the solar investigations, I hope an effort will be made to get at the differences in radiation from different spots on the sun's surface in their successive rotations, so as to get the chronological variations in temperature, as well as the geographical differences. The com- plete course of work that you have sketched out covers all the prob- lems that have thus far been found worthy of study, and, of course, the observatory will take up new ones as fast as they develop. I should not encourage duplicating in the southern hemisphere all the investigations that are to be conducted in the northern, but there are some problems that could advantageously be studied at both observatories. On account of our knowledge of atmospheric con- ditions at the stations Charcani and El Misti, that location has some advantages, but there is still hope of finding an equally advantage- ous location on the mountains of Ecuador or southern Colombia. When such a station is found, it should be devoted especially to studies on nebulae and stars, such as are described in your article 3, and perhaps also to less extensive studies on the determination of the solar radiation constant. From a meteorological point of view, observations on these northern and southern mountain stations are extremely desirable, and espe- cially if observers at the upper and lower stations can make absolute determinations of the altitudes and motions of the clouds or tempera- tures of the upper air by means of kite and balloon ascensions. Many other studies into the physics of the atmosphere, such as its gaseous constituents, its dust, and its motions, would constitute valuable additions to our meteorological knowledge. The special field to be occupied by such an observatory relates to the highest attainable atmospheric strata. If there is any specific matter on which I can be of use to your Committee, I shall always be happy to respond. [From Professor G. Midler, Royal Astrophysical Observatory , Potsdam, Germany. ~\ [Translation.] April 4, 1903. The plan to establish a great astrophysical observatory at a par- ticularly favorable site, and to provide it with the best instrumental equipment, will be greeted everywhere with lively interest. For 158 CARNEGIE INSTITUTION many problems of astrophysics the atmospheric conditions experi- enced at most of our observatories are to be regarded as unfavorable. Every increase in the transparency and also in the steadiness of the air marks an advance, and for this reason the choice of a site for a new astrophysical observatory should be made with the greatest possible care. The best conditions of the atmosphere are to be expected at a mountain station, and, according to my experience, an isolated peak is to be preferred to a point within a great mountainous region, where surrounding peaks under certain circumstances exercise a strong influence on the state of the atmosphere. The higher the chosen point the better, but height is not the only important factor. It is far more important that the observatory shall not be too difficult of access, and, before all e\se, it is essentia that the observations can be made with as great convenience audi ease as at any other observatory. Occasional observations, such as are made during a very short period on a very high mountain under the most difficult conditions, are ordinarily of comparatively little value. Many problems of astrophysics, such as the determination of solar radiation and investigations on the absorption of the atmos- phere, etc. , cannot be solved during short expeditions, lasting days or weeks ; they demand systematic study during a long period of time under the most varied atmospheric conditions — if possible, simultaneously from a peak and from a valley station. In my opinion, it would be best to establish the proposed principal observatory as high as possible, perhaps at an altitude of about 8,000 feet, but in any event so that it could be kept in operation through- out the entire year, or at least through the greater part of it, and be at all times accessible without too great difficulty. At this place the principal instruments should be established, and all investigations conducted which relate to the spectroscopy and the photometry of the fixed stars, particularly those in which photography is employed. An important requirement is the provision of a second permanent station at a height of about 1,000 feet. This should likewise be provided with the best instrumental equipment, with the object in view to provide for certain observations which should be made simul- taneously at both stations. It is naturally desirable that the direct distance between the two stations should be as small as possible, and that they should be connected with each other by telegraph and telephone. As regards the program of investigations prepared by your Com- REPORT OF COMMITTEE ON OBSERVATORIES 1 59 mittee, I think that this covers all fields of astrophysics in an ex- haustive way, and that hardly anything of importance can be added to it. I beg briefly to call attention to a few special investigations which, in my opinion, deserve special consideration : (i) Investigation of the atmospheric lines of the solar spectrum by simultaneous observations at both stations under the most diverse atmospheric conditions and at all times of the year. (2) Determination of the extinction of starlight by simultaneous photometric observations at both stations. (3) Thorough investigation of the photographic extinction by simultaneous photographs of given groups of stars. (4) Determination of the absorption for various regions of the solar spectrum by spectro-photometric measures. (5) Comparison of the light of the sun with that of the moon, the planets, and the fixed stars, to determine by continued observations whether any variation in the intensity of sunlight can be detected. In conclusion, I heartily wish you success in the great undertak- ing, and trust that your plans will soon develop in the interests of our science. \_From Professor J . Hartmann, Royal Astrophysical Observatory ', Pots- dam, Germany.] [Translation.] Aprie 12, 1903. Let me extend to you my heartiest congratulations on the aston- ishing advances which astrophysics has already made in America. It must be acknowledged without envy that the new continent has wholly outstripped the old one, and I would regard the establish- ment of a high altitude observatory as a glory to American science. When, as here in Potsdam, one is forced to observe with a great re- fractor under very bad atmospheric conditions, one soon comes to appreciate the enormous advantages of a high station with transpar- ent air and quiet images. I will mention here one point in particu- lar regarding which I have had some experience. If a telescope is to be used for spectrographic investigations it is necessary to have the greatest possible aperture in order to secure great light grasping power. If the ordinary ratio, about 1 : 18, of aperture to focal length is employed, this large aperture corresponds to a very great focal length, and in consequence of this the images become so bad with unsteady air that the advantage of the great aperture is almost l6o CARNEGIE INSTITUTION wholly lost. In this way, in an unsteady atmosphere, our photo- graphic refractor of 32 centimeters aperture gives practicahy the same results as the great refractor of 80 centimeters aperture. If a greater ratio of aperture to focal length is chosen, say 1 : 10 — quite apart from the great thickness of glass required in the refractor — new difficulties result, in that the aperture of the collimator can be only 1 : 10, and consequently for a given size of prism the collimator will be too short. At a high station these several difficulties are not to be feared. If you find a station with very quiet images, I should recommend for spectrographic work — either with very high dispersion on the brightest stars, c. g., for the determination of the solar parallax, or with smaller dispersion on faint nebulae and stars — a reflector with great aperture, and a ratio of aperture to focal length of about 1 : 30 or still less. I should also choose such a construction as to permit the spectrograph to remain in a constant position, with the collimator horizontal or in the direction of the earth's axis. Such a spectro- graph with long collimator, very short camera, and very high dis- persion would be best adapted to carry out the very important in- vestigation on the motions within nebulae to which I recently called attention. Our apparatus here did not permit me to accomplish much in this direction. If the spectrograph were built in a fixed position, not suspended from the eye end of the telescope tube, it could be made much more stable and also easily maintained at a con- stant temperature. It would thus be possible to employ very long exposure times. A horizontal mounting is also to be recommended for spectroheliographs of the largest dimensions. It is important to make these photographs with a very large solar image, in order, for example, to be able to study with precision the motions within a sun spot. Spectrographic studies of the zodiacal light and the aurora should also be included in the program. I heartily wish success to the great undertaking, and it will give me pleasure if I can aid it in any possible way. [From E. Walter Maunder, Esq., Royal Observatory , Greenwich^ May 14, 1903. With regard to the question of astrophysical research, my own position has led my thoughts in two directions. To me sun spots seem to be the most important subjects of stud}'. Our work at Greenwich consists, as you well know, in taking two REPORT OF COMMITTEE ON OBSERVATORIES l6l photographs of the sun daily on a scale of i decimeter to the solar radius and measuring one of these for the area and position of the spots. So far I think we fulfill our purpose sufficiently well. A larger scale is not necessary for positions of the accuracy we seek; indeed, the scale of i decimeter to the solar diameter was suffi- cient for that purpose and was less costly and the photographs were more manageable in size. To attempt to push the work of measure- ment and reduction to a further refinement would immensely in- crease the cost, and I doubt whether it would repay the outlay and trouble. But when we come to the question of the details of the spot forms and of their changes, then this scale is certainly not adequate. I greatly wish, and have done so for years, that we had here a second telescope with which we could take comparatively small areas of the solar surface on a scale of at least i meter to the solar radius. I think this is needed to supplement the other. But the study of spot spectra is much more urgently needed. My own slight experience of it with a most hopelessly inadequate instru- ment was sufficient to make me feel that it was absolutely one of the most important lines of research. I have always felt it a great misfortune that Sir Norman Lockyer, in the work which he has carried on at South Kensington for so many years, should have devised the method of recording just the ' ' twelve most widened lines. ' ' It seems to me in every way a badly devised scheme. If a long series of observations are conducted by one and the same observer, I should think it ran a great chance of stereotyping more or less accidental impressions. If the observer is often changed, we have no longer any means for comparing observa- tions made at different times ; and, at best, if we assume the ob- servations free from all personality and absolutely immaculate in quality, they seem to me to tell us hardly anything at all. The general character of any particular spectrum — not to speak of im- portant details — is left absolutely without record in such a system. Sir Norman Ivockyer's chief result, namely, that the most widened lines change with the progress of the spot cycle, opens out a great number of questions. First, the spots at maximum are not only more numerous, but they run much larger than at minimum. It would be most important to observe both at minimum and at maxi- mum a series of spots of a definite size. I would suggest, as it is a size sufficiently frequent even at minimum, a spot of 200 to 300 millionths in area. Clearly it is a great assumption, if we find a 1 62 CARNEGIE INSTITUTION certain spectrum given us by a spot of area 200 at minimum and another spectrum given us by one of 2,000 at maximum, to ascribe the change to a quality in the period (if I may so express it) when it may be a function of the size of the spot itself. Further, the average spot group goes through a certain pretty well defined routine in the course of its growth and decay. Now, if we are at the mini- mum of the cycle, our groups run small, and it is only (in most instances) during one particular phase of its development that a group is likely to be a tempting object for spectroscopic examination. At maximum we may have plenty of giant groups, which can easily be followed spectroscopically during their whole career. Here, again, is a point which wants to be followed out. If we record a given spectrum for a certain spot, we have not learnt all that we can unless we trace the history of that spot back to its rise and onward to its disappearance, and determine at what particular stage of its develop- ment the observation was made. We want to know whether we can associate different spectroscopic appearances with — (1) The size of the spot ; since the larger spots may be assumed on the average to be the deeper. (2) The stage of its development. The depth may alter with the age. (3) The changes that are going on in the group. (4) The progress of the general solar cycle. (5) The type of the spot group. I have put the type last, out of its logical order, because it has seemed to me that, though the great majority of spot groups con- form to one general type of evolution, yet occasionally we get spots of a very distinguishable form, and it is these spots, when of im- mense size, and not spots of the normal type, that are clearly and unmistakably associated with magnetic storms. It would be no small matter if we found that such spots exhibited some distinct spectroscopic peculiarity. As to the method of observation, clearly the photographic regis- tration of spot spectra should be the routine one ; but it certainly should not exclude the direct visual work. Just precisely as our daily photographs of the sun's surface at Greenwich, however ad- mirable for their purpose, leave us without any record of the pro- cesses of rapid change, so it would be with the photographic regis- tration of sun spot spectra. They cannot possibly render direct work unnecessary. REPORT OF COMMITTEE ON OBSERVATORIES 1 63 Might I quote from a letter to me from Mr. Evershed on this subject. He writes : ' ' We are apt to become too familiar with suu spots to be sur- prised at their occurrence ; but I am sure that when their origin and meaning is really understood, a key will be found to a great many other solar and stellar problems. I consider that as a prelim- inary the spot spectrum should be investigated with a bolometer in the visible region and infra-red to find out whether the discrepancy between thermal and visual estimates of spot darkness is real, and, if so, where in the spectrum is the excess of radiation measured thermally. "Another point to clear up is the resolution of parts of the spot band into lines observed by Young and Duner. Does this apply to all spots and to all parts of the spectrum, and is the emission spec- trum of the photosphere itself really continuous under high disper- sion ? ' ' It seems to me that until the fundamental radiation of spots is satisfactorily cleared up the study of widened lines is of secondary importance." The other subject to which my attention has been directed is the study of Jupiter. It seems to me that that planet ought not to be left to the scrutiny of amateurs, but should be systematically observed at some permanent and endowed observatory. As the sun is the only hot star which we can study in detail, Jupiter is the only cold star, and we are fortunate in having representatives of both ends of the series within our reach. In my connection with the British Astronomical Association, my attention has been drawn to the special field for work which this planet offers. The Association has done what it could in the matter. Its object was the training of amateur observers, and their direction to real systematic pur- poseful work in place of the desultory star gazing which is too often all that amateurs achieve. So far it has been most successful, and the Jupiter Section numbers quite half a dozen observers of the very first rank, beside others who may in course of time attain the same skill. But an association such as ours can never be a substitute for a permanent observatory. A very large proportion of its efforts must be spent in the work of training ; there is no guarantee that any of its observers will be able to follow up a research for a long- continued period, and the means for the proper discussion of obser- vations are quite lacking. I might mention, as an example, one of our most active students of Jupiter, Capt. P. B. Molesworth, R. E., of Ceylon. He has been working there for nearly eight years, and in a single apparition has obtained nearly 4,000 transits of spots 164 CARNEGIE INSTITUTION across the central meridian of Jupiter, revealing not a few interest- ing relations ; but necessarily he will not be able to remain much longer at that station, nor can he give to his observations the full discussion they deserve. If work similar to his could be undertaken by a professional astronomer, who would have the time to fully dis- cuss his results, at a permanent observatory, which would secure continuity to the work, I think it would ere long lead to our under- standing the condition of Jupiter far better than we can at present. Obviously an equatorial or at least a tropical site for such an observ- atory would, as Captain Molesworth has found, have great ad- vantages. Q [From Professor Knid Angstrom, Royal University , Upsala, Swcdcn.~\ May 16, 1903. I beg you to excuse my long delay in answering your very inter- esting communication on the astrophysical observatory planned by the Carnegie Institution, but a great many duties have hitherto made it impossible for me to reply. I hope, however, that you will not see in that delay a proof of indifference regarding a question that in fact interests me profoundly. Unfortunately I can give no information as to the site of the ob- servatory, having no personal experience with regard to the atmos- pheric conditions in the mountains of California. The establishment of two corresponding observatories at different heights will certainly be most valuable for the scientific results. As to the choice of a place, it will probably be of great importance to study the local con- ditions. My experience, derived from visits to Teneriffe, is that on the northern side of the mountain it is almost impossible to get sat- isfactory results in solar observations, while the southern side is very favorable for that purpose. As to the instruments for measuring the total radiation of the sun, I am sure that the compensation pyrheliometer is at present the only convenient instrument, and I am willing to superintend the construc- tion of the instruments that the observatory may think proper to order from the mechanician Rose in Upsala. Probably the program of the observatory comprises also the regis- tration of spectral energy by means of the instrument of Professor Langley. I may, however, call your attention to the advantage of making the registration also with another instrument, with less dis- persion, which in a shorter time could give a general view of the REPORT OF COMMITTEE ON OBSERVATORIES 1 65 solar spectrum and of its changes. I send you an account of a sim- ple arrangement for that purpose. It would be of special interest if these observations could be com- bined with researches on the amount of humidity in the free atmos- phere (by means of kites). I hope to return later to certain ques- tions that I believe to be of great importance. It will always be a great pleasure to me if I can be of service to you. [From H. F. Ncwall, Esq., The Observatory, Ca?nb)idge, England.] Cambridge, May 22, 1903. I almost hesitate to put down some of the ideas that have occurred to me about the establishment of a large astrophysical observatory, for they are rather crude, incomplete beginnings than formed judg- ments, and if I put them down at all it is only in the hope that they may help to clear matters rather than with the idea that they can carry any weight. First of all, let me say it seems a grand project to provide for an observatory for observations of secular physical phenomena of solar origin. It is perhaps an open question whether it is desirable to pro- vide for allied stellar studies. Many people must share the same instinctive doubt about a universal observatory as about a universal instrument. One majr definitely count on individual enterprise to provide for many of the researches indicated in your paragraph (3). Existing observatories do or can or should deal with most of the studies referred to, and it would be a pity in any way to risk cramp- ing either performance or obligation in these matters. Moreover, there are the elements of competition; as, for instance, in determi- nation of motion in the line of sight for fainter stars one ma}' count on advance from existing observatories. If in your large astrophysical observatory large special apparatus were available it might well be desirable to let the place become, as it were, a court of final appeal, whither perhaps rival pioneers might themselves resort to put their views to the test. In such cases, for instance, it might be a matter of " more light " being needed, and the pioneers might be expected to take with them their own eye end apparatus for attachment to a large light grasping instrument ; but one would like to provide in every way against retarding small private enterprise and pioneering elsewhere. One must avoid any- thing that would lead to the position, " Oh, it is no use doing this or that ; they have that on their program up there." 1 66 CARNEGIE INSTITUTION Where natural competition is absent or periods of phenomena are long, there is a grand opening for a powerful combined attack. One may count, for instance, on special studies of solar rotation at exist- ing observatories, simply because the period is short, but probably the variation of such short period phenomena in the eleven year period could only be properly tackled in an observatory where the outsetting aim was the study of secular phenomena. Hence it seems to me that secular phenomena are the special province of such an observatory as you are contemplating ; and it would seem a wiser course to concentrate attention on such observa- tions as would have direct bearing on these, and to provide for a systematic discussion of observations already accumulated, as well as for a systematic study of phenomena in process of being observed, than to scatter forces on the study of many stellar problems. In many ways probably more advance could be made by enabling a single observer to carry out his observations in several stations successively. The solar radiation ' ' constant " is an instance in point. Considerations of this sort would lead me to think that in some ways it might be better policy not to lock up huge capital in one fine observatory outfit, but rather to help individual researches by providing means for having them carried on with, say, one or two complete outfits that could be moved to various points of the globe. As I say, I hesitate to commit these remarks to paper. I suspect you are far beyond the elementary stage that these remarks refer to. As to aims and researches, your program is a large one already. It is not clear to me why it should not include a new attack on magnetic disturbances, and possibly on atmospheric and electrical phenomena. \From Dr. Ralph Cope/and, Astronomer Royal, Royal Observatory , Edinburgh^ August 15, 1903. I am afraid you will think me remiss in only now replying to your letter of March 26 ; but I have indeed most carefully thought over your project and looked up my old papers on mountain observato- ries. I have not much to add to the views which I expressed in my paper on the subject in volume III of Copernicus , which you have ; but, when consulting it, kindly substitute on page 230, line 22, 1.32 inch for 0.7 inch. Another note on my South American trip, written for the British REPORT OP COMMITTEE ON OBSERVATORIES 167 Association Report for 1883, may interest you, and I therefore inclose a couple of copies. My own impression is that to reap the full benefit of a mountain station one should aim at a height of fully 11,000 feet, and if well within the tropics an elevation of 12,500 feet might be occupied throughout the year withont serious discomfort. Such an altitude in either temperate zone, however, would expose the observers to the most terrible weather and great hardships in the winter — e. g. , the floor of the Crater of Elevation of Teneriffe (7,200 feet, latitude 28^°), according to the late Professor C. Piazzi Smyth, is swept by violent snowstorms every winter. The experience of residents and travelers in your own mountains will furnish you with abundant further examples. My experience at Puno on L,ake Titicaca (12,500 feet), in latitude 1 50 50' south, proves that observations can there be carried on under favorable conditions of weather and temperature at all seasons of the year. Indeed, the sky, on the whole, is much clearer in the winter, and therefore better suited for observations in general, although there are doubtless certain solar investigations which could in that latitude be better prosecuted at a season when the sun passes within a few degrees of the zenith for many weeks in succession. In the months of October, November, and December the weather is often very fine, I was told ; but in January, February, and the early part of March clouds, and even a good deal of rain, are to be expected. As you will know from Copernicus, my experience in the Andes was confined to the neighborhood of the Mollendo-Puno route, where, through the courtesy of the railway authorities, mechanical and technical aid is readily procurable; but doubtless the same mechan- ical facilities would be offered on the Oroya railway, which, starting from Lima, in 120 south latitude, reaches a height of fully 15,600 feet quite near the Pacific seaboard. Unfortunately the disturbed political state of the country at the time of my visit prevented me from examining this railway, but from its position so near the rain- less coast it is very possible that the weather conditions near the upper part of the route may be fully more favorable than on the Mollendo railway. But I should here like to draw your attention to a point affecting the personal comfort and even safety of the members of an astro- nomical party on their way to a high-level station. In my opinion, the whole of the ascent should not be attempted on one day; the party ought to devote something like a week to inuring themselves 1 68 CARNEGIE INSTITUTION to an elevation of 7,000 to 10,000 feet before proceeding to the more trying height of 14,000 or 15,000 feet. In my own case, very much against my will at the time, I was detained at Arequipa (7,750) feet for a whole week, with the advantageous result that I experienced hardly any inconvenience when from there I went on to Vincocaya, at a height of 14,360 feet. I mention this in particular, as such very unfavorable reports are current regarding the railway journey on the Oroya line from Lima and the mortality among the workmen employed in constructing that very remarkable railway. As regards the desirable instrumental equipment, there is one point which I desire to emphasize. The mirrors of the reflecting instruments should be made of speculum metal and by no means of silvered glass. Polished silver is incomparably more liable to tarnish than good speculum metal. Besides, even what would be called a good film of silver on glass is in a considerable degree transparent to ultra-violet rays, as was pointed out by Stokes and Cornu many years ago (A?males de V Ecole Normale Supericurc, ser. 11, tome ix, 1880, pp. 22-23). Respecting the behavior of such a film with regard to the infra-red rays I have no knowledge, but doubtless your own Professor Langley has had abundant experience on this point. On the other hand, mirrors of speculum metal reflect the low grade heat rays of the moon, and all other rays up to the ex- treme known limits of the ultra-violet, with apparent equal com- pleteness. Moreover, a mirror of speculum metal, when made of the proper alloy and well polished, is, under proper care, one of the most permanent of known optical appliances. I have before me the Cassegrain mirror of a reflecting telescope of 6 inches aperture, made by Short in 1745 ; both it and the other mirrors of that telescope are, to use the words of Dr. Dreyer, ' ' as bright as if they had been polished yesterday." I must add, however, that the telescope, which formerly belonged to King George III, and is now at the Armagh Observatory, seems to have been but rarely used. We have here, however, a Gregorian reflector made by Cary something over 100 years ago, which is frequently used by us for watching the timeball, and though never repolished, is still so bright that one would hesitate to relegate it to the polisher. We have also the mag- nificent 5^2 -inch grating presented by the late Professor Rowland more than 20 years ago, also made of speculum metal, which is prac- tically as good as when it was first received by Lord Crawford, though it has been in very frequent use. During one course of observations this grating was exposed to the fumes from peat}' ground, which we REPORT OF COMMITTEE ON OBSERVATORIES 1 69 found very injurious to silver on glass, but which did not perceptibly affect the brilliancy of the surface of the grating. Doubtless you will be able to learn the exact composition of the alloy used for the Rowland gratings ; but probably the combination of 4 atoms of copper with 1 atom of tin, recommended by the late Lord Rosse in his account of the construction of the great telescope at Birr Castle, would yield an alloy capable of retaining its polish for many years. From Lord Rosse' s own account it seems that he himself used a somewhat softer alloy, with the consequence that the larger mirrors made by him required repolishing about once every two years ; but I may mention that the night air at Birr Castle Observatory is usually very damp, and that owing to the great mass of the mirrors they are very liable to get dewed. This brings me to another part of the subject. A serious objection to metallic specula, as usually constructed, is their great weight ; but this difficulty may be largely remedied by giving the metal a more suitable form than that of a simple circular slab or disc. By the use of suitable sand (such as is used in the produc- tion of the highest class of bronze castings) there should be no diffi- culty in casting a speculum with deep ribs on the back, which would be much lighter and relatively stiffer than a disc of the same diam- eter. For a mirror 54 inches in diameter, I would suggest making the ribs and face of a uniform thickness of ^ inch. By giving the speculum a total depth of 8 inches, it would probably be stiffer than any mirror yet cast, and with a suitable arrangement of the ribs would weigh about 1,200 pounds. Of course, I assume that the ' ' metal ' ' would be cast face downwards on a " bed of hoops ' ' of the proper curvature, as practiced by the late Lord Rosse, to insure that the surface to be ground and polished should be perfectly sound and almost exactly of the desired form. The possibility of casting a speculum of this shape was, in a great measure, set at rest by an experiment made by the present Lord Rosse, who cast an elliptical flat mirror some 1 1 inches by 8 inches with a ribbed back, some thirty years ago. This mirror was perfectly sound and took a very high polish. It was used as a diagonal mirror for the 6- foot New- tonian reflector. If I were trying the experiment I should be in- clined to honeycomb the mirror after this fashion, adding a " web" round the outside, but taking care to make every part, including the face of the mirror, of the same thickness to facilitate uniform contraction in cooling. It is almost needless to say that a casting of this kind would need to be carefully annealed. Provided the 12 170 CARNEGIE INSTITUTION pattern were made in two parts, back and front, of cast iron and carefully finished, it is quite possible that a uniform thickness of Y% inch would be quite sufficient ; this would reduce the weight of the finished speculum to 900 pounds. Probably the chief practical difficulty in making such a casting will be so to arrange the mold that it will readily yield to the contracting speculum- metal. Very much will depend on the nature and condition of the sand or loam used in forming the mold, but doubtless valuable advice on the whole process could be obtained from an experienced molder who has been accustomed to the production of complicated and fragile castings. In conclusion, if we regard the rapid progress in spectroscopy of late years associated with the improvement of the diffraction grating, it seems that this is probably no less due to the happy choice of speculum metal for the material of gratings than to the improved accuracy of the ruling. It is therefore reasonable that further ad- vances in many other branches of astrophysics may be expected from a return to the use of the solid metallic reflector in place of the mirrors of silvered glass now so much in favor. Acknowledgments. The Committee desires to acknowledge the important advice and suggestions received from Dr. Blihu Thomson, Professor Joseph N. Le Conte, Major George W. Stewart, Professor E. C. Pickering, Professor H. Rubens, Professor F. Paschen, Dr. S. W. Stratton, Mr. T. P. Lukens, Mr. James Gamble Rogers, Mr. C. A. Phillips, Mr. Wm. R. Staats, Miss A. M. Clerke, Professor H. H. Turner, Mr. John Broder, Mr. James layman, Dr. G. K. Gilbert, Dr. C. Hart Merriam, and others, particularly from Mr. Charles G. Abbot, Assistant in Charge of the Smithsonian Astrophysical Observatory, who, with the approval of Secretary L,angley, furnished a very large amount of detailed information. PAPERS RELATING TO GEOPHYSICS Page Report on Geophysics ; by C. R. Van Hise 173 Report on Construction of Geophysical Laboratory ; by George F. Becker.. 185 Geophysical investigations suggested; by Adams, Cross, Iddings, Kemp, Lane, Pirsson, Washington, and Wolff 195 (I7i) REPORT ON GEOPHYSICS By C. R. Van Hise, ADVISER IN GEOPHYSICS. CONTENTS. Page. Why a geophysical laboratory should be established 173 Scope of a geophysical laboratory. 175 Establishment of a geophysical laboratory at Washington 175 Opinions of geologists as to importance of a geophysical laboratory. ... 176 The work of a geophysical laboratory 178 The relations of liquid and solid rocks 178 Minerals and rocks from aqueous solutions 179 The deformation of rocks 180 The constants of rocks 181 Basis of selection of problems suggested 181 Cooperation in geophysical work 182 Branch laboratories 183 Seismology 183 Cost 184 In the report of the Advisory Committee for Geophysics submitted last year, the establishment of a geophysical laboratory is somewhat fully considered. This report I was asked to supplement. Before taking up additional points it may be well to briefly summarize the reasons already advanced for the establishment of such a laboratory. Why a Geophysical Laboratory Should be Established. In recent years there has been no more striking development than cooperation in industrial enterprises. Whatever may be thought about certain aspects of such cooperation, there is no question that from the point of view of abundant cheaply manufactured products, industrial cooperation has been of enormous advantage. Science has reached a stage in its development in which coopera- tion is as essential as cooperation in business. When the sciences were young — indeed, until very recently — work was done in each in comparative independence of others. But the independent advance of the sciences has left unoccupied great intermediate fields. This (i73) 174 CARNEGIE INSTITUTION is illustrated by the rise, within the last quarter of a century, of physical chemistry and astrophysics. Van't Hoff, Ostwald, and others, seeing that there was a great unoccupied field between physics and chemistry, began the occupation of it. The great results reached by these men placed their names very high in the roll of those who have contributed fundamental ideas to science. More recently we have seen the marvelous rise of astrophysics. The scien- tific fruits yielded by occupying the ground between astronomy and physics have not been less important than those which have come from occupying the ground between chemistry and physics. The purpose of a geophysical laboratory is to take possession of the vacant ground between geology and physics and geology and chemistry. So long as geology remained a descriptive science it had little need of chemistry and physics; but the time has now come when geologists are not satisfied with mere descriptions. They desire to interpret the phenomena they see in reference to their causes — in other words, under the principles of physics and chemistr}*. If this be done the intermediate ground between geology and physics and chemistry must be occupied. This involves cooperation between physicists, chemists, and geologists. If such cooperation be under- taken in a systematic way upon an adequate scale, it is believed that there will be a greater revolution in the science of geology than it has hitherto undergone. Instead of being a descriptive science, it will be a science reduced to order under the principles of physics and chemistry, or, more simply, under the laws of energy. It is also believed that incidentally the sciences of physics and chemistry will be enormously advanced by the investigations undertaken. As showing the advantages which may come from the cooperation of geologists with scientists in the other branches, there may be mentioned one kind of cooperation, which has already begun upon a considerable scale, which does not necessarily require a laboratory : cooperation between geologists and mathematicians. In the past, many mathematicians have taken up geological problems, but usually their discussions have been unsatisfactory because important geolog- ical data were omitted from their premises. But by cooperation with a geologist the mathematician is enabled satisfactorily to apply his mathematics to geological problems because he has a full state- ment from a competent geologist as to the geological factors which enter into the problems. The mathematician publishes his results and gets full credit for his work. The geologist then applies these results to his geological problems. Thus by action and reaction REPORT ON GEOPHYSICS 1 75 between the geologist and the mathematician rapid advance is being made in knowledge of the early history of the earth, knowledge which could not possibly have been reached by geologists alone or by mathematicians alone. In a geophysical laboratory the geologists would cooperate with chemists and physicists in a similar manner. Expert chemists and physicists would apply chemical and physical methods to the prob- lems of geology. The phenomena and the various conditions under which they were probably produced would so far as possible be made clear to the chemists and physicists in advance of their work. The results reached by the chemists and physicists would then enable the geologists to advance their part of the work. This would lead to further suggestions to the chemists and physicists. One man would not be working for another. The men in the different sciences would be working together for the advancement of knowledge. They would publish their results separately or jointly, as seemed best. Thus by cooperation, action and reaction between men in the three different departments, the great field between geology and chemistry and physics would be occupied. The fundamental work for the new science of geophysics would be done. The results which would follow from geophysical work on a large scale are believed to be at least as great as those which have come from occupying the middle ground between physics and chemistry and between astronomy and physics. If a geophysical laboratory were established at Washington, this work would be done in America. Scope of a Geophysical Laboratory. The Advisory Committee for Geophysics in its report of a year ago proposed a twofold plan : First, the establishment of a geo- physical laboratory at Washington ; and, second, cooperation with all existing institutions or men now engaged in geophysical work. These two phases of the subject will be considered in order. Establishment op a Geophysical Laboratory at Washington. The report of the Advisory Committee referred to discusses broadly the various problems which should be taken up in a geo- physical laboratory and gives a provisional plan for the construction of such a laboratory. The time available to the committee for the 176 CARNEGIE INSTITUTION preparation of its report was short, and there were included in the report all important problems of geophysics which occurred to the committee. There was not sufficient time for consultation with geologists as to which of the problems proposed are most pressing, nor with physicists as to which of the problems experience has shown can be attacked with the certainty of securing results. My supplementary work has therefore taken these directions. The proper construction of a geophysical laboratory is considered by Dr. G. F. Becker, who submits an independent report upon this subject. Opinions of Geologists as to Importance op a Geophysical Laboratory. In consulting with geologists as to the lines of work which seem to them essential for the progress of the science of geology, it has been necessary to lay before them the general project of a geophysical laboratory at Washington, so that incidentally their views have been learned as to the importance of the establishment of such a laborar tory to the progress of the sciences of geology, physics, and chem- istry. Upon this matter there has been but one opinion : that the establishment of a geophysical laboratory along the lines proposed a year since by your Advisory Committee for Geophysics would be of the very greatest service to science. This view has been expressed by directors of national surveys, presidents of geological societies, presidents of national academies, and man)7 eminent geologists. It seems unnecessary to extend this report by inserting all the state- ments upon this subject made by various men, but a few may be inserted by way of illustration. Dr. J. J. H. Teall, Director General of the Geological Survey of Great Britain, says he has "no doubt that a central laboratory of geophysics in Washington, organized in the manner which is sug- gested in the report of the committee, would contribute very largely to the progress of science." Sir Archibald Geikie, formerly directo- of the same Survey, says in reference to the plan of the committee: ' The scheme seems to me well considered and likely to lead to the most important results in the future. * * * International co- operation is destined in the future to play a large part in the progress of science, and the geophysical laboratory at Washington might be made a powerful medium for establishing and fostering this broad spirit of brotherhood in research." Professor Tornebohm, of the REPORT ON GEOPHYSICS 1 77 Swedish Geological Survey, says: " In my opinion, the plan of estab- lishing a geophysical laboratory is a grand one. Ably conducted, such an institution may no doubt proffer elucidation on many an obscure question and powerfully promote the progress of many branches of geology and petrology in general." Professor Seder- holm, of the Geological Survey of Finland, says: "The enterprise which you hope to start aims at nothing less than to lay a new and in many respects more certain base for geological science. There can be no question about the exceedingly great advantage to the science of such experimental studies. If they have till now played an inconsiderable part in geology, it has been mostly because it has not been possible to make them on a scale in any measure adequate to that of nature. ' ' Professor Suess, President of the Royal Acad- emy of Science in Vienna, says: " I would heartily envy the country which might first boast of such an institution." These opinions are in accord with those expressed by leading physicists and chemists to the Secretary of the Carnegie Institution and published as an appendix to the report of the Advisory Com- mittee for Geophysics. These men, all of whom speak of the im- portance of geophysics to geology, or to geology and science in general, include Poncaire, Lord Kelvin, Ernst Mach, Becke, Kohlrausch, Van't Hoff, G. H. Darwin, and Nernst. The establishment of a geophysical laboratory was also discussed with many geologists at the International Congress of Geologists at Vienna this year, and there was but one opinion among represent- ative geologists — that the foundation of a geophysical laboratory would do work of fundamental importance for the science of geology. Indeed, the Council of the International Congress of Geologists unanimously adopted a statement concerning the subject which was accepted without dissent from any source by the entire Congress. This statement is as follows : " It is a well known fact that many of the fundamental problems of geology — for example, those concerning uplift and subsidence, mountain making, vulcanology, the deformation and metamorphism of ore deposits — cannot be discussed satisfactorily because of the insufficiency of chemical and physical investigations directed to their solution. Thus, the theory of large strains, either in wholly elastic or in plastic bodies, has never been elucidated, while both chemistry and physics at temperatures above a red heat are almost virgin fields. " Not only geology, but pure physics, chemistry, and astronomy would greatly benefit by successful researches in these directions. Such researches, however, are of extreme difficulty. They would 178 CARNEGIE INSTITUTION require great and long sustained expenditure as well as the organ- ized cooperation of a corps of investigators. No existing univer- sity seems to be in a position to prosecute such researches on an adequate scale. " It is therefore, in the judgment of the Council of the Congres Geologique International, a matter of the utmost importance to the entire scientific world that some institution should found a well equipped geophysical laboratory for the study of problems of geology involving further researches in chemistry and physics. ' ' In view of the foregoing facts, I think I may unhesitatingly assert that not only the geologists of this country, but the geologists of the world, and all the chemists and physicists who have given any atten- tion to the subject, believe that the results which would be obtained by the establishment of a geophysical laboratory would lead to funda- mental advances in the science of geology and great advances in the sciences of physics and chemistry. The Work of a Geophysical Laboratory. The general lines of work of a geophysical laboratory are fully set forth in the first report of the Advisory Committee. It has been my aim to supplement this part of the report by ascertaining the nature of the problems which geologists regard as most pressing and which chemists and physicists regard as capable of being successfully at- tacked. I am not able to make an exhaustive statement in these respects ; but, as a result of many conferences, I can specify certain lines along which enough work has been done to make it certain that important results will follow from adequate investigations. While the problems here mentioned are by no means exhaustive, they are sufficiently numerous to show that there is ample work which should be taken up at once to occupy a geopl^sical laboratory for many years. Some of these problems are as follows : ( 1 ) The Relations of Liquid and Solid Rocks. — A line of work along which many geologists are asking for information is that concerning the relations of liquid and solid rocks. They want to know the melting points of rocks, the temperatures at which rocks crystallize from magma, the relative specific gravities of melted and crystal- lized rocks, the effects of slow cooling upon the crystallization of rocks with and without pressure, the solution of one kind of rock in another, and, in short, all the phenomena which concern the trans- formation of magma to crystallized rock and of crystallized rock to magma. Upon these various points almost no information is avail- REPORT ON GEOPHYSICS 1 79 able, and yet reliable knowledge in reference to thern is necessary before the phenomena of vulcanism can be put upon a scientific basis. Experiments in laboratories on a small scale show that this work can be done. But the work has never been done upon an ade- quate scale, nor is there any probability that it will be done upon an adequate scale, so that the results can be applied to the history of the earth, until a well equipped geophysical laboratory is con- structed with sufficient funds to operate on a large scale. IyOrd Kelvin suggests that in experimental work involving many of these points at least a cubic foot of the melted rock should be taken. Among other Europeans who mention experimental work along these lines as essential are Dr. Ernest Schwarz, of the Geo- logical Commission of the Cape of Good Hope ; Professor L,oewinson- Lessing, of the Polytechnic Institute of St. Petersburg ; Professor Vogt, of Kristiania, and Professor Suess, of Vienna. Also the ne- cessity for this kind of work has been especially emphasized in America by an important group of geologists, including Adams, Cross, Iddings, Kemp, Lane, Pirsson, Washington, and Wolff. Their views upon this and other pressing investigations in geo- physics are set forth in a paper accompanying this report. The carefully systematized, comprehensive plan of work outlined in this paper will be of great assistance to the experimenter if a laboratory is constructed. Sufficient work has been done by Morosiewitsch, Doelter, Brun, and others to show that an investigation of the relations of fluid and crystallized rocks will be very fruitful. In America, Professor Carl Barus, under the direction of Clarence King, once began investiga- tions upon fluid rock, but this work was unfortunately discontinued because of lack of funds. Little work along this line is being done anywhere simply because of the lack of properly equipped labora- tories with adequate funds to carry on such necessarily expensive work. If such work be provided for in a geophysical laboratory at the Carnegie Institution, no one can doubt that scientific results of the first order will be obtained. (2) Minerals a?id Rocks from Aqueous Solutions. — Another class of investigations is the artificial production of minerals and rocks from aqueous solutions. This involves a study of natural solutions, both those of the sea and those in openings in rocks, in order to determine the conditions under which minerals crystallize from such solutions. Already the study of natural solutions with reference to the crystal- lization of salt and gypsum has been undertaken by Van't Hoff. 180 CARNEGIE INSTITUTION This great chemist has reached many important results, but he points out that very much remains to be done, and especially recommends this line of study to be taken up on an adequate scale in a geo- physical laboratory. Experiments should be carried on with aqueous solutions under various pressures and at various temperatures. The higher temperatures should approach those of magmas, in order that the relations of crystallization from magmas and crystallization from water may be learned. It is held by some that there is grada- tion between these. Sufficient has been done by various workers to show that very important results can be reached by the investiga- tions proposed, and a well organized, comprehensive series of ex- periments is now needed. It is certain that the conditions under which many of the minerals produced in nature from water solutions can be produced in the laboratory. Only when this is done shall we have an adequate basis upon which to judge of the kinds of min- erals that are produced in nature from aqueous solutions and their manner of formation. The study of natural underground solutions and the artificial pro- duction of minerals have a most intimate relation to ore deposits. Already studies along these lines have led to large advances in knowledge of the development of ores. This the men engaged in mining have recognized. Very recent contributions upon this sub- ject have been of great practical importance in the exploration and exploitation of ores. There is unanimity of opinion among geol- ogists that experimental studies on underground solutions and the artificial reproduction of the natural minerals will lead to correct theories of ore deposition and also give results of practical value, the magnitude of which cannot now be estimated. (3) The Deformation of Rocks. — Elaborate experimental work should be done upon the deformation of rocks under different conditions of speed, temperature, pressure, and moisture. At the present time Dr. Frank D. Adams, at Montreal, is engaged in the slow deforma- tion of one rock — marble — on a small scale. Indeed, in this work he has the support of the Carnegie Institution ; but experiments along this line need to be carried through long periods of time for many kinds of rock on a much larger scale than heretofore, in order that the results may be applied with safety to the observed deforma- tion of the vast masses of material of the earth. But already suffi- cient preliminary work has been done to show that this is a field for laboratory investigations which will certainly yield important results to the science of geology. REPORT ON GEOPHYSICS l8l Dr. James Dewar, Professor of Chemistry in the Royal Institution of Great Britain, is now engaged in testing the strength of rocks at the temperature of liquid air. Already he has reached remarkable (unpublished) results ; but he states that the apparatus and equip- ment at his command are entirely inadequate to carry on experi- mental work on the deformation of rocks at low temperatures on a scale that such work demands in order to give satisfactory results. He says that if a laboratory of geophysics were established the deter- mination of the breaking strength of various rock masses, by com- pressive, tensile, and tortional stresses, should be made at low tem- peratures. He says further that a complete determination of the elastic constants of rocks at different temperatures, under stresses of various kinds, should be made. Professor Dewar states that by the low temperature work upon very small masses of a few varieties of rook in his laboratory he expects to show merely that very impor- tant results can be reached by this line of work, and thus to lay out a great field for extensive work along the same line. Such work as that proposed by Professor Dewar is not provided for anywhere in the world. Such work is especially appropriate to a geophysical laboratory. (4) The Constants of Rocks. — Another set of problems which many geologists desire attacked concern the constants of rocks at various temperatures and pressures, such as their densities, their coefficients of expansion, their specific heats, conductivities, etc. The lack of knowledge of these constants, which can certainly be determined by experiment, has stood in the way of the progress of geology in va- rious directions. The need for work along these lines is especially emphasized by L,ord Kelvin and Professor Dewar, and is discussed by Dr. Becker in his report of last year. Basis of Selection of Problems Suggested. In mentioning the foregoing broad lines of investigation I have confined my statements to those which are urgently demanded by many geologists as necessary for the progress of the science. They represent the consensus of opinion of the many geologists with whom I have conferred rather than my own views. I have pur- posely omitted the problems mentioned in the first report of the Advisory Committee for Geophysics that are somewhat more remote from the present pressing problems of the geologist and the student of ore deposits. In order to recall some of the lines of work which are not here 1 82 CARNEGIE INSTITUTION considered, it may be said that all of the great problems concerning the atmosphere set forth in the first report of the committee are wholly omitted ; also the great problems dealing with the interior of the earth have been ignored. Finally, all the problems along the border line of astronomy and geology which concern the early his- tory of the earth have been omitted. By these omissions I do not mean to imply that each of the lines is not of profound importance. Indeed, I believe that all should ultimately be taken up in a geo- physical laboratory. It may be taken for granted that a deeper insight into the order of the universe is a sufficient reason — indeed, is the most important and fundamental reason — for investigations in science. All of these omitted lines fall within this class of studies, but the report of the Advisory Committee for Geophysics has already fully covered these problems. A special purpose of this supplementary report is to emphasize the point that there are many problems of immediate importance to the science of geology and to a knowledge of ore deposits which deal with the part of the earth that we can see, concerning which experimental work is demanded by the geologists of the world, because lack of such work stands in the way of the advance of science. Cooperation in Geophysical Work. I shall next consider the second part of the proposal of the Ad- visory Committee of last year — that of cooperation in geophysics. The plan of the Advisory Committee provided for the use of branch laboratories in various parts of the world. It was thought it might be necessary to construct an occasional small branch laboratory, but, so far as possible, it was proposed that all existing laboratories should be utilized to the fullest extent; also the plan of cooperation pro- vided that the central laboratory at Washington should be a clearing- house for the geophysical work of the world. This clearing house would acquire accurate information as to the geophysical work being done in all laboratories of every country. Any scientist who wished to know the present status of knowledge in reference to any prob- lem and what others are doing, so that he might take up work which should not duplicate that already done or being done by others, could apply to the Carnegie Institution at Washington and obtain the needed information. No part of the general plan of the Advisory Committee has received more universal approval by geologists, physicists, and REPORT ON GEOPHYSICS 1 83 chemists of various countries than its proposal for cooperation in geophysics. Branch Laboratories. It has been suggested, especially by Professor I^oewinson-L/essing, that a branch laboratory in the Hawaiian Islands, which are now a possession of the United States, would give unexampled opportuni- ties for the study of vulcanism. The majority of the present living volcanoes are comparatively small. In Hawaii are the greatest of the existing volcanoes — those that are most nearly comparable to the ones which must have existed when the vast lava plateaus of various parts of the world were produced. If a branch laboratory were established in Hawaii, there can be no question that the knowl- edge of the phenomena and causes of vulcanism would be greatly advanced. Seismology. Another line along which cooperation is especially urged by various European geologists is seismology. It is unnecessary to urge the importance of seismological investigations both to science and to constructional work. At the present time there are many seismological stations scattered over various parts of the world. However, for an adequate study of earth tremors it is advisable that additional stations should be established at a number of wisely se- lected places in the more remote parts of the earth. Professor Milne at Shide, Isle of Wight, has for many years been receiving records of a large number of the instruments now in use, but the work has now become too large for him to carry, and he asks for assistance. Recently it was arranged that Strassburg be a center of information for seismology, but some countries have refused to cooperate in this plan. The time is now ripe for some institution with adequate funds to arrange a broad scheme of cooperation between the various interests and to be the medium which harmonizes them, and thus to systematize the seismological work of the world. Many have said to me that the unique position of the Carnegie Institution, free from all entanglements and prejudices, places this institution in by far the most advantageous situation to accomplish this work. Indeed, a number of geologists have said that, so far as they can see, unless the Carnegie Institution takes up this work, the same chaotic con- dition of affairs that has existed in the past will continue. It is believed that in securing the cooperation of all the men engaged in 184 CARNEGIE INSTITUTION seismology and in coordinating all of the work on seismology, a laboratory of geophysics at Washington would find one of its greatest opportunities. Cost. As to the cost of a geophysical laboratory, the committee of last year submitted an estimate which it thought sufficient to provide adequately for the great plans laid out by it. If the scope of the proposed laboratory be confined to the more pressing lines of work indicated in this supplementary report and to other problems of an equally pressing character, and the more remote problems are ignored for the present, the cost of a laboratory can be very considerably reduced. Indeed, to get very important results, it is not necessary that all of the problems discussed in this report shall be taken up at once. If a laboratory were established, the governing body could best decide which problems should be undertaken after it was known how much money was available. After deliberate consideration of the matter from the minimum point of view, rather than from the point of view of what is desirable, I have come to the conclusion that work of very great importance can be done in geophysics for $50,000 per annum ; but in order not to greatly delay work, it is strongly urged that $100,000 be appropriated toward a building. This would make it possible to begin work on a productive scale much sooner than if only $50,000 per annum were appropriated, and from this fund it were necessary to construct the building and purchase apparatus. My recommendation is, therefore, that there be appropriated for the construction and maintenance of a geophysical laboratory $100,000 and $50,000, with the expectation that the latter appro- priation will be an annual one. While with the amount suggested it will not be possible to press the various lines of geophysical work with the speed which many strongly hold to be exceedingly desirable, I feel confident that great, indeed revolutionary, results to the science of geology will be obtained. CONSTRUCTION OF GEOPHYSICAL LABORATORY Report by George F. Becker. CONTENTS. Page Origin of report 185 Institutions visited 186 Magnetic disturbances 187 Electrical disturbances 187 Two desirable constant temperatures 187 Annual mean temperature 187 Difficulties of varying temperatures 188 Importance of uniform temperatures 188 Special difficulties in America 1 89 Avoidance of heat-flux 189 Notes on ventilation , 1S9 Suggestion that vibration of piers be damped 190 Research called for 191 Construction of laboratory building 191 Subdivisibility 192 Basement work rooms 192 Interior work rooms 192 Number of stories 193 Estimates of expense 193 Problems of geophysics 194 Origin of Report. In March, 1903, Mr. Walcott requested me to cooperate with Professor Van Hise in gathering information abroad with reference to the construction suitable for a geophysical laboratory, and in regard to the problems which could be profitably studied in such a laboratory were it to be built. After consultation with Professor Van Hise it was decided that the most important features of labora- tories are the means adopted to secure stability of piers and the methods of obtaining constant temperatures. Laboratory construc- tion must determine in what measure stability of instruments and constancy of temperature can be attained. On the other hand, to the investigators who occupy the laboratory after completion must be left in large measure the details of apparatus and of methods of research. 13 (185) 1 86 CARNEGIE INSTITUTION Laboratory construction is a matter of extreme importance and one which has been, relatively speaking, neglected. Vast ingenuity has been applied to the perfection of apparatus, while little pains has been taken to provide for that freedom from mechanical and thermal disturbance without which many instruments of precision cannot possibly give the best results of which they are capable. Hence also the work done in an ill constructed laboratory, other things being equal, will be inferior in quantity and quality as com- pared with that achieved in a suitable building. Institutions Visited. In accordance with the plans thus laid, I visited the Cavendish laboratory at Cambridge, the laboratory of the Sorbonne and the astronomical observator)^ at Paris, the laboratory of the Bureau In- ternational des Poids et Mesures at Sevres, the physical laboratories of the universities of Strasburg and Wiirzburg, the geophysical laboratory of Gottingen, the laboratories of the Physikalisch-Tech- nische Reichsanstalt of Charlottenburg, the laboratory of the Normal Aichungs Komission of the same place, the Astrophysical observatory of Potsdam, the physical laboratory of the University of Leipzig, the cryogenic laboratory, and the Astronomical observatory of Leiden. So far as possible, I consulted the chief physicists or astronomers of these institutions on the main points of my inquiry. Professor J. J. Thomson was absent and Professor Onnes, of the cryogenic laboratory, was engaged on the day of my visit. On the other hand, I had instructive interviews with Professor George H. Darwin, Professor Charles Chree, Sir Archibald Geikie, Professor E. Suess, and others. Nearly everywhere I have found physicists dissatisfied with the construction of their laboratories and fully persuaded that radical improvements are possible. Satisfactorily firm piers have been con- structed only at Potsdam and Leiden, and in both these places the successful result seems due rather to natural conditions than to peculiarities of construction. Fairly uniform temperatures, except- ing in underground chambers, have not been attained, although a majority of physicists are of opinion that they might be brought about. Heating and ventilation are usually no better than in any ordinary office building. An ideal laboratory would be free from magnetic, electrical, or mechanical disturbances and from unintentional changes of temper- REPORT ON GEOPHYSICAL LABORATORY 1 87 ature. It would be possible to maintain any room at any desired temperature for any desired period of time consistent with good lighting and ventilation. Such conditions cannot be fully realized. Magnetic Disturbances. Magnetic observations are so subject to disturbances that in prac- tice it is found needful to provide for them in separate buildings, free from iron and as remote as possible from industrial establish- ments. For more general laboratories, therefore, purely magnetic disturbances may be left out of account, and iron may be freely employed in construction so far as it does not lend itself to the prop- agation of mechanical vibrations. Electrical Disturbances. Electrical disturbances are of two orders of magnitude: Trolley lines using an earth current produce serious electrical disturbances at a distance of at least one mile, while trolley lines with a double overhead or underground metallic circuit, as well as carriages deriv- ing power from storage batteries, are innocuous at a distance of only a few hundred feet. Two Desirable Constant Temperatures. Except in deep subterranean chambers, it is difficult at best to maintain uniform temperatures. Far greater is the difficulty of changing the temperature of a room at will, for a very long time must elapse before the massive masonry of the walls and piers acquires the new temperature. For these reasons it appears inex- pedient to attempt more than two temperatures in any laboratory, except perhaps in one small room. One of these temperatures is the mean temperature of the subsoil, say 90 or io° C. in temperate latitudes, and the other is a comfortable temperature for work, say 200 C. Annual Mean Temperature. The maintenance of the lower temperature with extremely slow variations of a few degrees is not difficult in cellar or subcellar spaces. It is also possible, as Professor Wiechert has shown, to keep the air in such spaces moderately dry. Mr. Wiechert admits the air to his seismometer house through a galvanized-iron tube, 1 88 CARNEGIE INSTITUTION which is convoluted between the double walls of the house and pro- vided with drips. The tube enters the inner chamber near the ceil- ing and passes round the entire inner space, always at a slight slope, so that all condensed moisture trickles backward. From the air tube air escapes into the instrument room through small holes in the side of the tube. The result is, for some purposes, a very satisfactory one, attained almost without expense. In a larger laboratory a somewhat different method would probably be more convenient and more effective. Difficulties of Varying Temperatures. Attempts have been made in Europe to control the temperature of large apartments by providing them with double metallic walls in which hot or cold solutions circulate, but these efforts have not been successful. In warm weather, when cold solutions must be employed, the walls drip with moisture, the instruments suffer, and the operators fall ill. This would be avoided by supplying the apart- ment with air not merely cooled but dried, just as a room in winter may be heated by a hot-air furnace. In this country more attention has been given than in Europe to cooling apartments with dry air. The Bureau of Standards has de- veloped arrangements for this purpose which will be in operation in a few weeks, and it is said that the Stock Exchange in New York is being similarly equipped. The experience obtained by the Bureau of Standards should be carefully considered before any specific plan is adopted for a geophysical laboratory. Importance of Uniform Temperatures. In my opinion, a modern laboratory should be supplied in summer with dry, cool air, the temperature of which is under control. Such air of appropriate temperature should be admitted to the cold sub- terranean chambers when required, and should be furnished to the ordinary laboratories in such quantity as to keep their temperature down to 20° C. = 68° F. In winter the rooms must, as a matter of course, be warmed. If the problem of maintaining a laboratory at constant temperature is not wholly simple, it is surely of small complexity as compared with those of physical research, and it can- not be doubted that were its solution requisite to the success of a commercial enterprise, an appropriate method would soon be de- veloped. Yet it is unquestionable that physical research would REPORT ON GEOPHYSICAL LABORATORY 1 89 proceed much more rapidly and effectively in a laboratory of fairly constant temperature. Some physicists, indeed, maintain that it is sufficient to attempt constant temperatures only within pieces of apparatus, but in this view I cannot agree. A standard bar, for example, may be measured in a case kept nearly at constant tem- perature by circulating liquids or by electric resistance ; but this temperature depends in part on the radiation of the case, and this on the temperature of the apartment. Again, the accuracy of gal- vanometers, and all similar apparatus, is greatly promoted by a substantially uniform temperature. Special Difficulties in America. In the eastern United States the natural atmospheric temperature varies so enormously and so rapidly as greatly to interfere both with the accuracy of instruments and the capacity of observers. Heat flows from piers to instruments, or in the reverse direction, so fast as to be most disturbing and wholly incalculable, and this flux renders the more minute measurements most uncertain. Thus, even more than in Europe, it is desirable that an American labora- tory of the highest class should be isothermic. Avoidance of Heat Flux. The maintenance of a temperature of 200 C. in a laboratory is at- tended with other difficulties besides that of supplying cool or warm air. In the laboratory of the Normal Aichungs Kommission it has been found that the flow of heat downward through the piers is a very disturbing factor at the best, and I there received the excellent suggestion that the exposed portion of the piers should be made of metal, in order that it should readily take on the temperature of the observing room. The metal plate should stand on three points, and the stratum underlying them should be of the most non-con- ductive material which can be found. Hard magnesia brick is almost ideal in this respect, and I suggest that the masonry of the piers be faced with this material. Notes on Ventilation. Insulation, excepting in very deep subcellars, is not sufficient to establish uniformity of temperature, even in Europe. In the east- ern United States, the annual variation being much greater than on the other side of the Atlantic, insulation is still less effective. T90 CARNEGIE INSTITUTION Modern American engineers have reached the conclusion that either in warming or cooling apartments diffusion of the air, unaided by stirring, cannot be relied upon to produce substantial uniformity of temperature. Air of nearly the desired temperature must be forced to circulate through the room at velocities which are sensible, but are not necessarily great enough to constitute deleterious drafts. In my opinion, cold air should be admitted in summer at numerous openings near the ceiling of rooms, while heating should be effected in winter by warm air entering at many openings in or near the floor. Ventilation should not be left to natural draft alone, for this sometimes fails ; it should always be possible to control it by electric fans or other engines. Thermostats should be employed, but they should be of very solid and durable construction, and they should be carefully checked until found entirely satisfactory. Suggestion that Vibration of Piers be Damped. The subject of stable piers is one of the most vital importance to laboratory construction, yet it has been most imperfectly investigated. There is no question whatever that superficial vibrations of the soil are largely cut off by a trench excavated about a pier, and for this reason the whole new laboratory at Leipzig is inclosed in a trench. On the other hand, the base of a pier under ordinary conditions is its stablest portion, so that the top of a tall pier vibrates far more than its base. It occurred to me that the vibrations of a tall pier might be damped, for example, by filling the trench about it with coarsely ground cork or some similar substance. I seemed to see an illustration of this principle in Wiechert's seismometer, an instru- ment which is, of course, intended to respond to the most minute vibrations. Except for a very essential device, this seismometer, when once agitated, would continue to vibrate for a long time with a period of its own. This would, of course, defeat its purpose. To render it a " dead-beat " instrument, it is damped by air cataracts, and thus records only the tremors communicated to it by the earth. Now, why should a pier not also be damped by air cataracts, cork- packing, or other means ? In Leiden I met what seems a most sur- prising confirmation of this idea. The Cryogenic Laborator)- and the astronomical observatory are built on soil which overlies some 40 feet of soft mud resting on sand and clay. This seems a most unpromis- ing position for stability, yet experience has shown that it is not so. The piers are built on groups of piles driven well down into the REPORT ON GEOPHYSICAL LABORATORY 191 sand and sheathed in planks. The buildings are built on systems of piles inclosing those of the piers. Now these piers are so stable that in the Cryogenic Laboratory observations with the most delicate galvanometers are entirely practicable when five condensing pumps are at work in a room only a few yards distant, while in the observa- tory there is not the least trouble in using the quicksilver mirror. On the other hand, at the Bureau des Poids et Mesures wagons on a high road some hundreds of yards away shake the piers, and the quicksilver mirror is seriously disturbed even at the bottom of the catacombs near the Paris Observatory. It would seem to me that the mud underlying Leiden damps the vibrations of the piers much as cataracts would do, and that this is the only probable ex- planation of their success, which I understand to have been attained without special reference to the efficacy of mud for this purpose. Research Called for. The subject is one needing and deserving research. In the well- known Julius suspension, means are adopted both to secure damping and to place the instrument in a node of vibration. The extra- ordinary efficacy of this suspension is well known. It appears to me perfectly possible to devise piers, after proper investigation, in which vibrations will likewise be damped and in which the upper surface will lie in a node. While the results in Leiden show that mud underlain by firmer material is not a bad foundation for a laboratory, no one, I take it, would deliberately select such a situation if solid rock or a firm saprolite (decomposed rock in place) were available. Construction of Laboratory Building. All the most delicate experiments of a laboratory would be car- ried on on piers and in the basement or the first floor of the building, but great stability sufficient for a large class of experiments can be obtained in a second floor by the use of masonry arches. For this reason I cannot recommend for a laboratory the steel beam construc- tion now used in ordinary buildings. In such buildings the oscilla- tions due to wind would be very sensible, and any jars due to moving apparatus or similar causes would be communicated to other portions of the building much more readily than in an arched construction. 'Professor Wiechert has measured quantitatively the deflection of his main laboratory building by the wind. 192 CARNEGIE INSTITUTION I find physicists most positively of the opinion that the walls of laboratories should be broken by as few openings as possible. No flues for ventilation or any other purpose should be included in the thickness of the walls. Plumbing and piping should be placed in wells reserved for the purpose and conveniently accessible. As material for the construction of laboratories, nothing seems preferable to good brick well laid. Experiments long ago made by officers of the Coast and Geodetic Survey show that sandstone should be rigidly excluded from every portion of the building. I know of no objection to concrete ; provided, however, that the stone used be sharply angular and on no account consist of rounded' pebbles. The walls of a laboratory should be very thick and massive, not less than three feet in the lower story. All doors and windows should be double. It is the habit to inclose the constant-tempera- ture rooms in double walls, but I believe that a single wall sur- rounded by cork brick would be equally good. This admirable material is much used as a non-conductor ; for instance, in the in- sulation of the clocks of the Paris observatory. Subdivisibility . — An important feature of laboratory construction is the subdivisibility of the work rooms. As investigations succeed one another, rooms of different dimensions become desirable. The smallest room requires one window and one door, with independent gas, water, and electrical connections. So far as possible, it should be arranged that such rooms may be separated from one another by partitions of hollow brick, which can be removed without interfering with the structure of the building. Thus the size of the work rooms can be reduced to a minimum or enlarged as required at a trifling expense. Basement Work Rooms. — The basement of a laborato^ should be of sufficient height to be used conveniently as working space. In a well drained locality it affords the very best of working rooms. Interior Work Rooms. — Opinions differ somewhat as to the best gen- eral plan for a laboratory. A few physicists object to internal rooms lighted only from above, considering them gloomy and subject to accident from the breaking of skylights. On the other hand, such rooms afford the best constant-temperature spaces and are freest from mechanical disturbance. Again, so-called wire glass and other simple expedients give ample protection from danger of falling glass. For these reasons a majority of physicists approve of inter- nal rooms surrounded by a corridor, and this again inclosed by outer working rooms. The corridor, among other advantages, affords REPORT ON GEOPHYSICAL LABORATORY 193 most desirable space for placing cases in which to store apparatus and supplies. In my opinion, the offices of a laboratory which are to be fre- quented by outsiders should be partially isolated from the main building, as indicated in the following rough diagram, so that doors leading into the main building should be opened only when this is unavoidable. Of-?-'' Wl 1 /ceo. Co r rider. Inner Work £ $ 0 Rooms. i i Outer r° Number of Stories. — Three stories seem necessary and sufficient for a laboratory. The lowest, or basement, story should be on the ground, with one or two deep subterranean chambers beneath for secular experiments. The second story should be on arches above the basement, and would afford excellent working rooms with piers of fair stability. A third story would serve to protect the second and can be usefully employed for photographic work and experi- ments not dependent upon piers. Estimates of Expense. — Estimates of the expense of building a labo- ratory were given in the project submitted by me to the Institution nearly a year since. These were based on the cost of the laboratory of the Reichsanstalt, and were set down at $250,000. I know of no way to improve upon this result except by having an architect draw 194 CARNEGIE INSTITUTION preliminary plans for a building. The heavy walls and arches would be expensive, but the absence of flues and the flat wall sur- faces called for would tend to keep down the cost. Problems of Geophysics. I have consulted Messrs. George H. Darwin, Charles Chree, Kohl- rausch, and others on the problems which can be attacked in a geo- physical laboratory with fair prospects of success. They appear to agree with the views set forth in Appendix 1 to Report of Advisory Committee on Geophysics (Carnegie Institution Year Book, No. i, pp. 44-58). In particular, Professor Chree, who is the leading expert on the theory of the vibrations of a sphere, agrees with me that some 3rears of mathematical work must be done before seismo- logical observations can be duly interpreted. Such mathematical investigation should certainly be undertaken as soon as possible. Investigations into finite stress and strain, rupture, the steady flow of heat, diffusivity, aqueo-igneous and dry fusion, together with the whole chemistry and physics of high temperatures, afford brilliant prospects of important results and wide applications of the conclu- sions drawn to terrestrial problems. It would be easy to enumerate many specific problems, and this I have done in a manuscript report to Mr. Walcott, entitled " Remarks on Geophysics," dated March 21, 1902 (not published), but the work indicated in the last paragraph would worthily occupy any institution for many years, and a consideration of what should be undertaken when this is done may well be postponed. Washington, D. C, October 2, 1903. GEOPHYSICAL INVESTIGATIONS SUGGESTED In the interests of the Science of Petrology several of us, who have devoted much of our time and energies to petrological matters, call attention to a statement of some of the problems in the line of physico- chemical investigation which could be undertaken in a properly equipped laboratory and urge the importance of laying the matter before the geological committee of the Carnegie Institution in order that it may be favorably inclined toward the investigations proposed, some of which are already being carried on under the patronage of the Carnegie Institution. It will be noted that many of them are of far-reaching importance to the advancement of general geological problems, of which the knowledge of the properties and history of rocks forms a very con- siderable part, the problems connected with rocks affecting the whole geological system. It therefore happens that problems stated in this connection may naturally be restated in others. INVESTIGATION OF IGNEOUS ROCKS. I. Determination of Changes of Condition Accompanying Changes of Temperature. A. With normal atmospheric pressure. i. Change of volume and of viscosity ; that is, the rigidity, melting point, and liquidity of — (a) Rock glasses of known chemical composition, corresponding to known igneous rocks. (b) Glasses of single minerals. (c) Crystals of single minerals. This involves fusion in open crucibles with the determination of temperature thermo-electrically by methods employed by Dr. Barus and Dr. Day in the laboratory of the U. S. Geological Survey. B. With high pressures in closed vessels. The effect of increasing pressure on the volume and the vis- cosity— rigidity, melting point, liquidity — of rock glasses, and glasses and crystals of known minerals. (i95) 196 CARNEGIE INSTITUTION II. Determination of the Behavior of Solutions of Min- erals in One Another. A. With normal atmospheric pressure. 1. The temperature at which two minerals will go into solu- tion in one another, and the temperature of solidification of the mixed solution. For various pairs of rock-making minerals such as — Quartz and orthoclase. Orthoclase and albite. Orthoclase and pyroxene. Pyroxene and olivine. 2. The point of saturation in each case for various tempera- tures. 3. The solution of gases in liquid minerals and rocks. (a) The rate of absorption (see also Diffusion, head- ing III) and the limit of saturation for differ- ent temperatures. (b) The relation between the composition of the liquid mineral or rock and the limit of satu- ration. (c) The effect of dissolved gases on the viscosity of the liquid rocks. B. With high pressure in closed vessels. The influence of increasing pressure on the solution of various minerals in one another, on the saturation and solidifying point, and on the solution of gases in the liquid rock and on the limit of saturation, especially the effect of dissolved gases in liquid rock under high press- ure on the viscosity of the liquid. (See Diffusion, below.) III. Determination of the Rates of Diffusion in Liquid Rocks and Minerals. A. With normal atmospheric pressure. 1. The rate of heat conductivity in solid and liquid rocks and minerals at various temperatures. 2. The rate of absorption and transmission of various gases in liquid rocks of different compositions. GEOPHYSICAL INVESTIGATIONS SUGGESTED 1 97 3. The rate of molecular diffusion in liquid rocks by os- motic pressure. The solution and diffusion of mole- cules of one kind of mineral in liquid rocks or minerals of other kinds. This has a direct bearing on the solution and diffusion of rocks in molten magmas, and on the theory of rock synthesis, and on that of magmatic intrusion by solu- tion of the surrounding rocks. 4. The recognition of possible colloids in liquid rocks, which may form in the presence of gases, such as water gas, under pressure ; the colloidal condition of silicon hy- droxide, aluminum hydroxide, and ferric hydroxide being easily conceivable. It is also possible that more complex, alumino-silicate molecules may become col- loidal. This might be detected electrolitically in mol- ten magmas in the presence of water under pressure. The bearing of this on the problem of differential diffu- sion and differentiation is important on account of its bearing on the question of the origin of different kinds of igneous rocks. B. With high press7cre i?i closed vessels. 1 . The effect of increasing pressure on heat conductivity in solid and liquid rocks. 2. The effect of increasing pressure on the diffusion of gases in liquid rocks. 3. The effect of increasing pressure on molecular diffusion by osmotic pressure. 4. The rate of molecular diffusivity at high temperatures and high pressures in liquid rocks containing various amounts of gases. This has an important bearing on the probably high rate of differentiation in the more liquid molten magmas. IV. Crystallization from Liquid Rocks with Temperature Determinations and Observation of the Time Ele- ment. A. With normal atmospheric pressure. 1 . The determination of the temperature of saturation and the rate of crystallization of simple minerals in cooling liquids of the same composition. 198 CARNEGIE INSTITUTION Open crucibles. — The production of crystals of quartz, orthoclase, albite, as well as those of augite, oli- vine, anorthite, etc. 2. The crystallization of several heteromorphous minerals from cooling mixed solutions of the same. Examples: Anorthite and olivine. L,eucite and diopside. (a) The order of crystallization related to the rela- tive amounts of the two mixed minerals. (b) The rate of crystallization. ) In the same rela- (c) The habit of the crystals. j tions. 3. The crystallization of isomorphous minerals from mixed solutions. Such as — The series of albite — anorthite feldspars. The series of pyroxenes. The series of amphiboles. (a) The order of crystallization. (b) The production of distinct kinds, or of crystals of average composition. That is, the pro- duction of zonally different crystals, such as the lime-soda feldspars in many cases, or of a homogeneous crystal of intermediate compo- sition. The relation between these modes of crystallization and the rate of crystallization. B. With high pressure in closed vessels. 1 . The effect of the presence of dissolved gases on the crys- tallization of anhydrous crystals from liquid rocks. 2. The effect of dissolved gases on the crystallization of — (a) Hornblende as opposed to pyroxene. (b) Biotite as opposed to orthoclase and hypers- thene, etc. 3. The relation between pressure and the chemical character of the minerals or salts crystallizing from a mixed solution. 4. The possible crystallization of hydrous minerals such as epidote, analcite, muscovite, from liquid rocks under pressure (to account for " primary " epidote and anal- cite in igneous rocks). 5. The possible crystallization of calcite and other carbonates from liquid rocks. GEOPHYSICAL INVESTIGATIONS SUGGESTED 1 99 6. The relation between the size of crystals and — (a) The composition of the mineral liquid — the sol- vent. (b) The rale of cooling. if) The mobility of the molten magma, and its con- tent of gas. (d) The pressure. 7. The relation between the habit (shape) of crystals and- (a) The composition of the mother liquor. (b) The rate of growth. (V) The molecular mobility of the mother liquor. (d) The absence or presence of currents or motion at the time of crystallization. (e) The pressure. 8. The texture of rocks in its relation to — (a) The development of phenocrysts by partial crys- tallization of the magma at one rate and the solidification of the remainder at another rate (to be effected by change of physical environ- ment, change of temperature, or pressure). (b) The diverse rates of growth of diverse minerals in mixed solutions. (c) Synchronous intergrowths of mixed salts, as of quartz and orthoclase. (d) The effect of localized ' ' crystallizers ' ' in pro- ducing centers of crystallization resulting in spherulites, segregations, etc. ( vL. •!* 1* *J» rf+ rf* *T» *y» *j» Washington, D. C, Ja?iuary 27, 1902. \Professor G. Neumayer, Director of German Naval Observatory, Hamburg, to Mr. Bauer, .] [Translation.] I take pleasure in acknowledging receipt of your esteemed favor of the 1 2th ult., enclosing a copy of the Plan for a Proposed Inter- national Magnetic Bureau of the Carnegie Institution, and to inform you that I have read the same with very great interest. I am of opinion that if this plan reaches its fulfilment, it is the most impor- tant step ever taken for the development of our knowledge of the earth's magnetism. The thought which underlies this plan must appeal to every one who has ever been engaged in geomagnetic investigations. In no other branch of geophysics is it more essential to extend the inqui- ries over the entire earth. Magnetic research, to be successful, requires the cooperation of the most competent investigators of all countries. As you know, I have occupied myself with the exhaustive collec- tion of magnetic results and with their discussion, and it may there- fore not be amiss for me to express my opinion regarding the possi- bility of success in this line of inquiry without the working together of investigators over the entire globe. Only by international coop- eration, as is successfully done in the case of the geodetic and astro- nomical sciences, is it possible to prevent useless efforts and regret- table errors. 208 CARNEGIE INSTITUTION At the ' ' Nattirforscher Versammlung ' ' in Hamburg last Septem- ber (1901), I presented for Professor Schmidt, of Gotha, a plan agreed upon by us for the establishment of an institute for the dis- cussion of geomagnetic results. To be sure, we had in contempla- tion only an institute for Germany. However, it was also the intention to include in its scope world-wide investigations. Your plan, however, as embraced in your proposition, is far more com- prehensive and promises the greater success in case it should be carried out. Through correspondence with Professor Schmidt, I learn that your plan has his indorsement. The salient points in your plan have been so well thought out, and have so thoroughly the impress of a truly international cooper- ation in terrestrial and cosmical magnetic investigations, inclusive of atmospheric electricity, that at present I am unable to add any- thing in the way of suggestion. Permit me, therefore, in concluding, to express the hope that your plan may meet with success, so that at last we may reach the goal and be able to penetrate more successfully the mantle of dark- ness still enveloping the phenomena of the earth's magnetism and electricity, thus adding one more to the already notable scientific achievements of the American nation. vL* *1* «X» vL> «J^ vL» vL» ^J1* *y* *|* *(* *T* *T* *T* I assure you that it will always be a pleasure to me to assist you to the best of my ability in carrying out the proposed plan. Hamburg, February u, 1902. [Professor E. Mascart, Director of Bur caii Central Meteorologique , to Mr. Bauer, ,] [Translation.] The project which you had the kindness to communicate to me in your letter of January 13 seems to me to be of very great scien- tific value. If it were possible to secure a participation in Mr. Car- negie's foundation, a first class piece of work could be created. The profound knowledge of the distribution and variation of the earth's magnetism all over the globe would, besides its evident service to navigation, not fail to contribute to the progress of sev- eral other sciences, especially to that of geology, electricity of the atmosphere, and even to astronomy, on account of the still unknown influence of the changes of the surface of the sun. PROPOSED INTERNATIONAL MAGNETIC BUREAU 20Q The science of terrestrial magnetism is, by its nature, essentially international, for it can be treated effectively only by the cooperation of observers of all nations, stationed on land and sea. The erection of an international bureau of the kind proposed, in the United States, would give to these investigations a mighty impulse. The program you have worked out seems to be very well prepared in its general outlines. **1* »A# »1* «^ *^ »^ *r% *y* "J* *T* 'i* *T* I shall speak about this matter before the Bureau of Longitudes, which occupied itself with this question some time ago, and I shall communicate to you the result of the discussion of this subject. Paris, Jamtary jo, 1902. [Genera/ L. Basso/, Preside?!/ of /he Bureau des Longi/udes, /o Mr. Bauer. ,] [Translation.] The Bureau of Longitudes has recently been informed by M. Mas- cart of the project for the organization of an International Magnetic Bureau of the Carnegie Institution. Our association would see with great satisfaction the realization of this project, which concerns ter- restrial and solar physics in as high a degree as it does navigation. The "Bureau des Longitudes," ever since it was founded, has always seconded, as far as its feeble resources allowed, all efforts which would tend to an increase of our knowledge of terrestrial mag- netism. *Af v^ vl^ *^ *A* *£* %t# sT** *n *^ *T^ *n *T* ^% I have the honor to send you the first pages of a general report, now in course of print, which will appear in the "Annals of the Bureau des Longitudes." You will see that the bureau has taken an initiative analogous to that which is proposed to the Carnegie Institution. It was of the opinion, as you are, that in an enterprise of such proportions one isolated nation would be powerless to bring together, in a sufficiently short time, the elements for a magnetic chart of the globe ; it has also made an appeal to the magnetic and meteorologi- cal observatories of all nations. A perusal of this document will show you that the ' ' Bureau des Longitudes de France" is especially prepared, by its methods, its 2IO CARNEGIE INSTITUTION instructions, and the observations already collected, to second the realization of your project. It is gratified that its efforts have been appreciated and would be happy to see one of its members officially associated with the organization of this important international undertaking. Paris, March 24., igo2. [Professor A. Schuster, Director of Physical Laboratory \ Owens Col- lege, Manchester, to the Carnegie Institution^ I have seen a proposed scheme for an international magnetic bureau, on which I should like to make the following observations : I believe that no material progress of terrestrial magnetism is possible until our knowledge of the magnetic constants of the great ocean basins, especially the Pacific, have been determined more accurately than they are at present. There is reason to believe that these constants may be affected by considerable systematic errors. It is possible that these errors have crept in by pajnng too much attention to measurements made on islands and along the sea coast. What is wanted is more numerous and more accurate observations on the sea itself. I have had occasion recently to consider this matter very carefully, and I have come to the conclusion that the observations that are going to be made in the Arctic and Antarctic regions will be of very little use to us until we can supplement them by measurement in other portions of the ocean. It would be most useful, to my mind, to make a complete survey round the world of two circles of latitude, one in the northern and one in the southern hemisphere, say 500 N. and 400 S. of two circles of longitude, say 1500 E and 1000 W., taking them as far north and south as can be done without much trouble. As regards reduction of observations, there can also be no doubt that private enterprise is no longer capable of dealing with it. Anybody who has not a staff of computers at his disposal is at present incapable of working out any ideas he may have. The problems which might be worked out are all of very consider- able scientific importance. Whether they are also of practical im- portance is not possible to affirm, but such practical utility is by no means excluded. The other investigations mentioned in the scheme are also of importance. Manchester, January 26, 1902. PROPOSED INTERNATIONAL MAGNETIC BUREAU 211 ^Professor W. von Bczold, Director of the Prussian Meteorological In- stitute, to Mr. Bauer. ~\ [Translation.] Your kind favor of the 13th ultimo [enclosing copy of plan of proposed International Magnetic Bureau] gave me very great pleas- ure. I have always had the feeling that it is comparatively easy to solicit funds for expeditions and similar undertakings designed to collect scientific material, whereas it is very difficult to obtain means or the necessary scientific aid for the discussion and utiliza- tion of the data collected. The difficulties and dangers to be overcome in expeditions evoke energetic young investigators and easily arouse interest in wide circles, while the onerous discussion of the collected material re- quiring tireless application and more penetrating insight is not valued in an equal degree ; and yet it is the critical discussion of the observations which furnish the actual results of the expedition and make the real contribution to science. This is especially true of magnetic investigations. For the establishment and maintenance of magnetic observatories, and especially for exploring expeditions, large means have been available. The reduction and discussion of observations, however, have been made only incompletely. For limited regions and for rather restricted purposes — e. g. , in the case of magnetic surveys of countries — most gratifying contribu- tions have been made, but for all problems embracing the entire earth, there are most keenly felt gaps in our knowledge. Thus, for example, the immense material gathered by the International Polar Expeditions of 1 882-' 83 has been utilized only to a very small degree, and so also in the case of the present international work, conducted in cooperation with the Antarctic Expeditions, whereby observations en ?nassc will be piled up. It cannot be seen at present how the prompt utilization and publication of the results is going to be accomplished. To be sure, Professor Adolf Schmidt, of Gotha, is at present engaged, with the aid of grants from the Prussian Academy of Sciences, to cover some of the above men- tioned gaps ; however, the means at his disposal are altogether too inadequate for the accomplishment of anything very noteworthy. I should therefore hail with delight, as in the interest of science, if a part of the most generous gift of Mr. Carnegie could be devoted to further magnetic investigation. ******* 212 CARNEGIE INSTITUTION Above all, however, does it seem to me to be important to submit to a critical and comprehensive discussion the immense pile of ob- servational data. This is all the more necessary because in recent times the obtaining of accurate data, owing to the advent of the electric car lines, is getting more and more difficult. Then, first, shall we reap the real benefit of the time, labor, and cost spent in the accumulation of observations. BERiviN, January 26, 1902. [Professors J '. Elstcr and H. Geitel to the Carnegie Institution^ [Translation.] Professor L,. A. Bauer has submitted to us for our consideration the plan which he proposes for an International Magnetic Bureau of the Carnegie Institution. With the earnest hope that this proposal may meet with your approval, we beg leave to suggest that it would be in full harmony with the proposed plan to combine with the organization of interna- tional magnetic work also the inauguration of observations pertain- ing to the electric condition of the earth and of the atmosphere, even though this at present may be possible only to a limited extent. As the principal electric problems, we might name the determina- tion of the strength of the earth's electric field and of the electric conductivity of the atmosphere (the so-called dissipation of elec- tricity), and the investigation of earth currents and the aurora. Since these matters have been investigated only within compara- tively recent times, the methods of observation and of reduction and the theoretical utilization of the results are as yet very imperfecta Nevertheless, there is reason to hope that, even with the present means, relationships between the electric phenomena of the atmos- phere and the earth's magnetic phenomena can be disclosed. At comparatively small cost for instrumental means and without adding very much to the work of the observer it would be possible, in our opinion, to institute systematic measurements of the electric intensity of the earth's field and of the conductivity of the atmos- phere at a few magnetic observatories as widely distributed as possi- ble. A few years' results at these places would then show whether it would be desirable to increase the number of stations or expand the work in other directions. WolfenbuTTEE, Jamiary 26, 1902. ARCHEOLOGICAL INVESTIGATIONS IN GREECE AND ASIA MINOR Report By T. D. Seymour. CONTENTS. Page Itinerary 213 The field assigned as limited by circumstances 216 Egypt 217 Turkish Empire 218 Syria 219 Asia Minor 220 Greece 222 Crete 223 Italy 223 Cyprus 223 Past Excavations : Greece 224 Islands 226 Crete 226 Cpportunities in Greece 228 Opportunities in Crete 230 Laws as to Export of Antiquities. ... 232 Contrast with former spirit 234 Present Excavations in Greece 239 Summary of Advice 240 Classical Archeology worthy of support 240 Itinerary. Bearing in mind your commission to inquire and report with re- gard to excavations near the Mediterranean sea, I spent the months of April and May of this year in Greece, among the islands of the ^Bgean archipelago, and in Asia Minor. On my way to Greece I visited the excavations at Pompeii, with which I was already fairly familiar. On my arrival in Greece I visited the ruins at Eleusis and heard lectures by Dorpfeld, the distinguished head of the Athe- nian branch of the German Archeological Institute, and by Wil- helm, the accomplished head of the Athenian station of the Aus- trian Archeological Institute, before the ruins on and about the Acropolis and near the harbors of Athens. I then made three tours (213) 214 CARNEGIE INSTITUTION with Dorp f eld, who has lived in Greece since 1878 and during this period has done more than all other scholars together for the ad- vancement of knowledge of classical architecture and Athenian topography. In Asia Minor I was with Professor Richardson, who has been for ten years director of the American School of Classical Studies at Athens. Since coming to England I have spent more than a month in the libraries of the British Museum, reading reports of explorations and excavations inlands "near the Mediterranean." In the course of my journeys in southern and northern Europe, I have been brought into close relations with several archaeologists of distinction, includ- ing some who have been engaged in excavations and other explora- tions, and I have used my best endeavors to secure from them, as from all other sources, the information which you desire. On the first tour with Dr. Dorpfeld our party visited the excava- tions of the American School at Athens, both at Corinth and at the Argive Heraeum, those of Dr. Schliemann at Tirynsand at Mycenae, of the Greek Archeological Society at Epidaurus, of Vollgraff at Argos ; then, passing to Arcadia, we saw the results of the work of the Germans and the French at Tegea and of the British School at Megalopolis ; then, crossing Arcadia, we observed the excavations of the Greeks at Dycosura. Thence we went to Ithome and to Olympia, where we spent three days ; thence to L,eucas (which Dorpfeld holds to be the Homeric Ithaca), to the classical Ithaca, and to Delphi, where the excavations of the French were carefully inspected. On this first expedition Dr. Dorpfeld had a party of about forty, mostly philologists, but several specialists in archeology. The most noted of the party were professor Diels, of the University of Berlin, and Professor Forster, of Breslau. Dorpfeld lectured from two to five hours every day, expounding the ruins with great care, so arranging his lectures as to touch on almost every topic of ancient architecture, though the order of the discussion was deter- mined by the geographical situation of the ruins, the prehistoric palace of Tiryns and the Argive Heraeum being followed by the visit to the sanctuary of Asclepius at Epidaurus, and this by the palace, fortress, and tombs of Mycenae, etc. The company com- prised so many scholars of special attainments that informal discus- sions often brought out details additional to the lectures. Special trains were in readiness whenever it was desirable and were stopped whenever Dorpfeld wished to show a particular object or view. For the trip to Eeucas, Ithaca, and Delphi a special steamer was char- CLASSICAL ARCHEOLOGY 215 tered, which should take the exact route desired and should stop according to the will of the head of the party. This first trip occu- pied fourteen days. The second tour covered twelve days, and was primarily for a visit to the islands of the JEgean, but provided also for visits to Poros, in Peloponnesus, and to Suuium, Rhamnus, and Marathon, on the Attic coast, which could not be reached so easily from Athens by land. The specially chartered steamer stopped at Eretria, on Eubcea, at least once, and in some cases twice ; at Andros, Tenos, Myconos, Delos, Syra, Paros, Naxos, Thera, and Melos, and at five stations on the shore of Crete — Heraclion (for Cnossus), Gurnia, Palseocastro, Phaestus, and Agia Triada. As on the trip through Peloponnesus, Dr. Dorpfeld lectured regularly, sometimes on the boat in preparation for the visit, as well as in the presence of the ruins, and in addition we had on Crete the hospitality and exposi- tions, at Cnossus, of Arthur Evans, the discoverer ; at Gurnia, of Miss Boyd ; at Palseocastro, of Mr. Bosanquet, of the British School at Athens, and at Phsestus and Agia Triada, of the Italian exca- vators Parabeni and Pernier, Halbherr, the chief excavator, being ill. This second party was constituted much like the first, but was rather larger, and comprised more dilettanti. The steamer could accommodate more persons than could find horses and mules for the ride across Arcadia, and the life was less strenuous than in Pelopon- nesus, although the physical exertions required in the visits to some of the islands were not slight. The third expedition with Dr. Dorpfeld was to Troy, setting out shortly after the return from the visit to the islands of the Archi- pelago. To Dorpfeld is due all the scientific results of Schliemann's excavations on the site of Troy — indeed, Schliemann died just be- fore the Homeric city was recognized — and here, as at Olympia, every stone was familiar to him. One morning he lectured more than four hours without interruption. At Troy we remained for three days, listening to lectures for at least ten hours, but having some time free for our own independent observations ; and from Troy we made an excursion to the heights of Bunarbashi, which before Schliemann's excavations was generally accepted as the site of Homeric Troy. The party to Troy numbered twenty five, being necessarily smaller than either of the others for lack of accommoda- tion. Some of us were quartered in Schliemann's old barracks, near the citadel, but the younger members of the party were obliged to sleep in a Turkish village nearly a mile distant. 2l6 CARNEGIE INSTITUTION The three trips with Dorpfeld were planned to include every im- portant site on which excavations have been made, either on the mainland of Greece or on the Greek islands, with the exception of Attica, which had been visited previously. Architectural and gen- eral archaological importance prevailed over historical interest or poetical associations. Thus the party was not taken to Sparta, nor to Thermopylae, or the Vale of Tempe, where only general impres- sions were to be gained from a brief stay. The call at Marathon was the only exception to this rule, and this lay directly on the route, in passing from Eretria along the Attic coast. In Asia Minor, our little party of four, by dint of vigorous exer- tions, and favored by excellent weather, accomplished in two weeks more than I had thought possible in the limited time at our disposal. Here, too, we visited almost every important site of past excavations : the British and Austrian excavations at Ephesus, the German exca- vations at Pergamon, Priene, Magnesia on the Meeander, and Miletus, and the French excavations at Didymi, as well as the less important explorations at Sardis and at Magnesia on the Hermus. At Perga- mon, Priene, and Miletus we were guests in the houses built for the use of the German excavators, and had the use of their plans and reports for the elucidation of the ruins. We visited also the exten- sive ruins of Hierapolis and Laodicea, a trifle more than ioo miles from Smyrna, and were also at Thyateira and Philadelphia, though we had no opportunity there to search for and make examination of any ruins. Thus we traversed a considerable part of each of the four great plains of western Asia Minor, in addition to the Troad, and saw the sites of the Seven Churches of Asia, and passed along the coast in a small Turkish steamer — so near as to give us a distinct view of the country from the west. Reluctantly we abandoned the plan of visiting the scene of the American excavations of Assos ; this place is not easily reached, and Professor Richardson was obliged to leave for America. Thus in the two months of my stay in Greek lands I had under the most favorable circumstances such a comprehensive view of the archeological excavations which have been made in those lands within the last forty years as few before me have had in the same length of time. The Field Assigned as Limited by Circumstances. The broad general field which you suggested for my examination receives from circumstances important delimitations. France and CLASSICAL ARCHEOLOGY 217 Spain, in general, may be left to explore the remains of antiquity within their own borders, and the feeling is general that Algiers and Tunis are also the proper field of France, which is officially doing much for their exploration, and doing this far better than a foreign expedition, because of the convenient cooperation of civil and military forces in a region which is somewhat unsettled. Danish archeologists desired three years ago to conduct excavations in the Cyrenaica, which was only superficially explored by the English — Smith and Porcher — forty years ago ; but conditions were found to be unfavorable, having changed for the worse since 1865, when they were, to say the least, extremely difficult. I have heard of plans made by those who are interested in Roman archeology for excavations on the sites of Roman towns in Africa, but I have no exact knowledge of them. Egypt. — In Egypt the work of exploration is being done very well, and with sufficient rapidity, chiefly by two expeditions — one from America, with funds supplied by Mrs. Hearst, of California, well di- rected by Dr. Reisner, who is assisted by Mr. Lythagce, and the other that of the Egypt Exploration Fund, which receives about half its support from America. This Egypt Exploration Fund has had, for more than a score of years, Dr. Flinders Petrie as the chief director of its work, and about fourteen years ago it instituted a much needed Archeological Survey of Egypt, which has published twelve annual volumes by Newberry, Griffiths, and Davies ; and half a dozen years ago the fund established a Grseco-Roman branch which has pub- lished five volumes of high importance, and is said to have on hand a mass of fragments of papyri which weighs tons rather than pounds. Dr. Petrie in the course of the last twenty two years has done more than any one else ever did in the field for the excavation of Egyp- tian monuments. In addition to these two principal expeditions, the Germans are exploring in a limited way, with an annual appro- priation of about $2,500 ; the French have recently dug a little with or through Arab explorers, but with comparatively unimportant results ; and for the next five years the University of Chicago plans to have a small expedition in Egypt, under the direction of Pro- fessor Breasted. If Alexandria, a Greek city on Egyptian soil, is considered apart, as it well may be, we may note that a commission of the Society for the Promotion of Hellenic Studies, after a careful examination, reports that excavations there would be very expen- sive, and do not promise to be remunerative. Egypt is not to prove an inexhaustible mine of antiquities, as 15 2l8 CARNEGIE INSTITUTION many seem to think. An experienced official of the Museum at Cairo believes that the great sites and fields of exploration in that laud will be virtually exhausted within fifteen years, and that later explorers will have only a gleaning from the harvest. A more cau- tious scholar thinks that the opportunities for exploration in Egypt may continue for twenty years yet, except the supply of classical papyri, which is likely to be exhausted earlier ; but the work of exploration is so well done now and is so largely under American influence that no reason exists for another special expedition to Egypt. A multiplication of agencies in so limited a field is not desirable, and no new leader would accomplish so much with the same means as the present explorers. Turkey. — The Turkish government theoretically approves of arche- ological explorations in its territory, and allows them under certain conditions. Naturally, the consent of the owner of the land on which excavations are to be made must be secured, a government inspector must be paid, etc.; but these are mere matters of detail. Practi- cally, however, the necessary firman for excavations is often delayed. Every request for such permission must receive the approval of the Sultan, and since the supreme head of the Turkish Empire allows little authority to his ministers of state and holds in his own hands all the reins of the chariot of government, so that many matters of importance to the realm are left without attention, no one can feel surprised that petitions which interest no Turk are often and long postponed. An American, Dr. Banks, recently has had action on a request for permission to conduct excavations delayed for more than two years (I think, for five years) on one pretext or another ; one site proved not to be available in the opinion of the government, because the neighboring tribes of Arabs were unruly and might cause trouble ; another site was not available because part of it was occu- pied by Turkish graves ; and similar excuses are found without diffi- culty by Turkish officials. But in the past, English and Americans have been allowed to make excavations in the Turkish Empire — wit- ness the American excavations at Assos and at Nippur, and the Brit- ish excavations at Koyunjik and at Ephesus ; and excavations are in progress at present in Asia Minor under the care of Germans, Aus- trians, and recently by the French. So, with patience, permission may be secured for any American excavations in that region. Well informed persons believe that Dr. Banks's request was opposed by an influence which would not be exerted so strongly against excavations near the Mediterranean. No longer would it be possible for a for- CLASSICAL ARCHEOLOGY 219 eigner to dig as L,ayard did in Assyria in 1845 and Schliemann at Troy in 1870, and di Cesnola on Cyprus, also in 1870, without formal permission from the Porte. The official eye is watchful of excava- tions. The Turkish law no longer allows a general permission for archeological excavations ; the firman is granted for only two years, and may be withdrawn if the excavation is not begun within three months ; it is for a single definite place, no more than ten square kilometers iu area ; and the Minister of Public Instruction may order at any time the suspension of the excavations. Practically, however, when a firman of this kind has once been granted, it is renewed with little difficulty. Doubtless the Porte has been more ready to grant special privileges to the Germans because of the intimate relations at present of the two empires. Syria. — In Syria two towns near Tyre are reported to show indica- tions of relations between the Carthaginians and later Ty rians or of old Phoenician settlements. These might afford information greatly de- sired j ust now. The discovery of a wealthy and artistic civilization in Crete, of the second millennium B. C, which had close relations with Egypt and yet was not dominated by it, rouses special interest in the inquiry with regard to the relations between Crete and the western shore of the Mediterranean. Did the Philistines go to their later homes from Crete, as some have thought, or did they from Syria influence the island? The Rev. Dr. Eddy, who has spent his life near Sidon and has kept in touch with archeological work, recom- mends the towns referred to, and thinks also that $5,000 or $6,000 expended in excavations on the site of Dan would be very remunera- tive in results. His opinion is the more valuable since he is perhaps the chief adviser of the natives in their archeological finds. A much more magnificent undertaking in Syria would be the exploration of the site of Antioch, on the Orontes, the most impor- tant of the cities founded by Seleucus Nicator, 300 B. C, in honor of the victory at Ipsus and named for his father, Antiochus — third in importance of the cities of the Roman Empire, being next to- Rome and Alexandria, a city which played a great part in the his- tory of Christendom, where "the disciples were first called Chris- tians," the patriarch of Antioch ranking with those of Rome and Constantinople, a city about which fierce battles raged during the Crusades. Antioch was the metropolis of the Orient, but it has been shaken frequently by earthquakes since its early ages. Ten times within the first six centuries it is said to have suffered greatly from this cause. The shocks of 457-458 and 526-528 A. D. are 220 CARNEGIE INSTITUTION said to have been particularly destructive. The Emperor Justinian rebuilt much of the town, but confined it in closer bounds. It is his walls that are preserved in ruins. They are said to be traced along a circuit of about 4 miles. In the fifteenth century the mod- ern town had only 300 houses. Now there are said to be 5,000 to 10,000 inhabitants, but these occupy only a small part of the ancient enclosure. Thus excavations can be made there with slight expense for the surface of the ground. With Autioch should be included for exploration the neighboring Daphne, only 5 miles distant, where stood a great temple of Apollo and which was a favorite retreat of the Seleucids and the Romans. ' ' For the architecture of but few cities of the world have we such connected reports for a period of 800 years," according to Professor Forster, of Breslau, who has made the most careful study of the ruins and who is most enthusi- astic in his recommendation of this as a place for excavations. He would be glad to give to explorers any assistance within his power. His recommendation is seconded by Freiherr Hiller von Gartringen, who has himself gained deserved note as an explorer and excavator. These excavations would cost not less than $50,000. They would throw light not only on the life of the Seleucid time, but also on the history of the Roman Empire. Asia Minor. — In Asia Minor, in the course of the last quarter of a century, much has been done in the way of exploration, our country having an honorable part in this because of the work of Professor Ster- rett, the results of whose labors fill the second and third volumes of the Papers of the American School at Athens. Professor Ramsay, of Aberdeen, the highest authority on the geography and history of Asia Minor, says in one of his books that he has had occasion to correct the -work of many of his predecessors, but that when he has followed Professor Sterrett he has found but a small gleaning left to him after Sterrett' s harvest. But the work of exploration in Asia Minor has been too sporadic to accomplish what is most needed, and often a single traveler has been over a route where at least three specialists were required. A party of three explorers — an epigraphist, an architect, and a topographer, with some knowledge of geology — who would supplement the work that has been done, would perform an important work for science. Even after the travels of Heberdey and Wilhelm, I am assured that very much remains to be done for the exploration of southeastern Asia Minor. Many ruins there deserve careful inspection and measurement, and possibly some might be found well worthy of excavation. Professor Sterrett is so CLASSICAL ARCHEOLOGY 221 bound by his duties at Cornell University that he could not be ex- pected to retain the conduct of such an expedition for two or three years, but he might be willing to take the leadership for a year, until his associates were thoroughly trained to the work. This work of exploration at present seems to me on the whole more important than the excavation of any known site in Asia Minor, although I shall go on to mention two attractive sites for excavation. Excavations in Asia Minor have been chiefly of Hellenistic rather than Hellenic sites, and little of an early time has been brought to light. The American work at Assos, next to the great work at Troy, is the chief exception. On the other great sites of excava- tion little has been found of the best Greek period, to say nothing of the oldest Greek period of colonization. Apparently the earliest sites of some of these towns have not as yet been found, while Per- gamon and Priene, of course, had all their glory in the later period. These explorations, then, have been disappointing in their results as regards the art and history of Greece at the time of its greatness, but they have rendered an important service in throwing unexpected light on the relations between late Greek and early Roman culture. Much that had been supposed to be of Roman development is now found to be of Greek origin in art, and particularly in architecture. Of unexcavated sites in western Asia Minor, two seem easily pre- eminent— Hierapolis and Laodicea. These lie near together, about ioo miles from Smyrna, but on the Ottoman railway, so as to be easy of access. Both are superbly situated. Each is virtually de- serted, L,aodicea having no inhabitants, but bearing a modest crop of grain, and Hierapolis being haunted rather than occupied by a small band of gipsies. Each has remains of two theaters, baths, aqueducts, early Christian churches, and the like. It will be re- membered that St. Paul in his letter (IV, 3) to the Church of Colossse, which is only 9 miles from Laodicea, refers to the work of Epaphras also at Hierapolis and Laodicea, which proves that these were early homes of Christian churches. Hierapolis was founded about 200 B. C, on a high bluff which commands the plain between the L,ycus and the Mseander and the great road from Sardis to the East — the road along which Xerxes led his forces in 481 B. C. and by which the younger Cyrus ' ' went up ' ' against his brother, ac- cording to the narrative of Xenophon, at tbe close of the same cen- tury. It was the birthplace of the philosopher Epictetus. The Apostle Philip and his daughter died there. Papias was bishop there in the second century of our era. It was the rival of Laodicea, 222 CARNEGIE INSTITUTION and connected politically with Pergamum, being "the center of native feeling, of Phrygian nationality in the valley." Inscriptions have been found there in large numbers ; 363 are published by Humann. It was destroyed by an earthquake in the first century of our era, but rebuilt, as is supposed, by the help of the Roman emperors. The excavation of the entire site of Hierapolis is ren- dered impracticable by the thick deposits of limestone which have been left on the southern half of the ruins by springs which are heavily charged with minerals. These deposits since the destruc- tion of the city are often 6 feet or more in thickness. Indeed, the bluff is a remarkable natural phenomenon. On either side of the ancient site is a petrified Niagara formed by these springs. The great theater, however, is well preserved, and lies so high that no limestone deposit has been made about it, and other important ruins also are free for excavation. The most thorough survey which Hierapolis has yet received w7as by a small party which remained only a fortnight, and hardly had time to turn over stones in order to see if these bore inscriptions. Laodicea presents no such difficulties as the neighboring Hierap- olis. The form of the long mounds which border the principal streets indicates that the rows of houses which lie beneath are con- cealed by no great depth of earth. This city was somewhat older than Hierapolis, being ascribed to Antiochus II and named for his wife L,aodice. So far as appears, no archeological excavations have been made there; but the ruins were plundered somewhat for the construction of the Ottoman railway. An ancient Greek inscrip- tion from I,aodicea lies face upward as a block in the platform of the neighboring railway station (Gondjeli). Greece, — The Greek government allows responsible societies or institutions to conduct archeological excavations under govern- ment surveillance, recognizing the reasonableness of the desire to have the antiquities uncovered and not having money enough to undertake all of this work. The Greek governmental oversight is in no respect vexatious, but is designed only to secure a strict observance of the laws with regard to antiquities. Private persons are allowed to conduct excavations in Greece only in the name of some responsible institution; otherwise the government so limits the authority of the excavator as to make the work an official excava- tion at the expense of the individual. No man may even make archeological investigations on his own land without the permission CLASSICAL ARCHEOLOGY 22 0 of the ephory, and the ephor will direct the work, determining even the number of laborers to be employed. Clearly, this law is intended to discourage irresponsible explorations, and it is entirely reason- able. Many foreigners would be glad now, as a century ago, to expend a little money in turning up the soil of Greece, although without any real scientific interest and not fitted, either by nature or training, for the conduct of scientific explorations. Crete . — The Cretan law with regard to excavations is similar to that of Greece, but the government has granted permission to excavate to scholars whose position is assured. Mr. Arthur Evans's extraordi- nary skill is well known to the Cretan authorities, and after our countrywoman Miss Boyd's excavations at Kavusi in the name of the American School of Athens she could have had no difficulty in securing permission to dig on her own account, though I believe her present excavations are for the American Exploration Society of Philadelphia. Italy. — The Italian government declines to permit foreigners to conduct archeological excavations on its soil, even in the way of mere superficial exploration. In the past such work has been allowed at times (as it was, freely, in the sixteenth to the eighteenth centuries), and hopes have been entertained that under suitable restrictions such permission might be again granted ; but as yet these hopes have not been fulfilled, and the policy of the government seems fixed, although attention has been called to the inconsistency of refusing this privi- lege to foreigners, while it is granted to Italians who are believed to desire the permission not because of their interest in archeology, but simply for commercial reasons. But if, as has happened in recent years, a foreigner wishes to have some house removed which ob- structs and covers important ruins, he can not conduct the work him- self, but must give the money to the Italian government, merely ex- pressing the desire that it should be used in a certain way. Cyprus. — Since Cyprus came under the power of Great Britain, the ancient sites on that island are practically reserved for British arche- ologists. Small excavations have been made, it is true, by both French and Germans, but only by way of exception ; in at least one of these cases the privilege was requested as a personal favor by an ' ' exalted personage." Under ordinary circumstances the British Foreign Office would not grant to foreigners permission to dig for antiquities on that island. 224 carnegie institution Past Excavations. Greece. — Thirty years ago no archeological excavations worthy of the name, according to present ideas, had been undertaken in Greece. The best had been the uncovering of the great theater of Dionysus at Athens, but this was not completed. The soil had been scratched a little on the Athenian Pnyx, a little rubbish had been removed from about the Parthenon, the French had spent six weeks in re- moving the earth from the temple of Zeus atOlympia, less time had been spent in clearing the sanctuary at Eleusis, many graves had been opened by unauthorized persons, and a few of the tombs in the Ceramicus had been opened by authority. Now, however, the principal and most promising sites have been subjected to a careful archeological search, and the list of places where important investi- gations of this kind have been made would read like a catalogue of the chief political, commercial, and religious centers of Hellas. Dodona, the earliest seat of the worship of Zeus in Greece, was discovered by Carapanos and excavated by him in 1875. Olympia, the seat of a famous oracle and of still more famous athletic con- tests— the chief common meeting ground of Greeks of all tribes, whether their homes were in Libya, Sicily, Macedonia, or Hellas proper — was excavated by the German Empire in 1 875-' 81 at a cost of about $200,000. Only in May of this year the French handed over to the Greeks the results of their excavations on the site of the sanctuary of the Pythian Apollo at Delphi, excavations which in their final stage lasted for ten years and which are said to have cost about what was expended for the similar work at Olympia. The site of the worship of Apollo at Delos was attempted by the French thirty years ago and the work was continued later, but was not completed according to modern standards, and it is to be resumed by them within a few months, an American, the Due de Eoubat, furnishing the money needed for this work. The ancient and hon- ored shrine of Demeter at Eleusis, the seat of the Eleusinian mys- teries, and the extensive sanctuary of Asclepius at Epidaurus, the chief seat of worship of the Greek god of healing, with temple, theater, stadium, and many other accompaniments of a health resort, has been excavated by the Greeks themselves rather gradual^. The earliest and chief seat of the worship of Hera in Greece, the Argive Heraeum, including not only the temples but also the neighboring por- ticoes and other buildings, was excavated by the American School of CLASSICAL ARCHEOLOGY 225 Athens, assisted bj^ the Archaeological Institute of America, from 1889 to 1893. The temple of Apollo at Bassae in Arcadia, from which the frieze was brought in 1812 to the British Museum, lay several miles from any town, and no indications have been found near it of any such complex of buildings as at Epidaurus or the Argive Heraeum, but the ground immediately about the temple has been searched by the Greek Archaeological Society. The French have investigated the site of the temple of Ptoan Apollo in Bceotia. The American School of Athens had the honor of uncovering the remains of what seems to have been the earliest site of the worship of Dionysus in central and southern Greece — Icaria in Attica, the home of Thespis, who was long considered the mythical founder of the drama, but who has assumed a clearer historical personality since these excavations. The ancient seats of wealth, culture, and power at Mycenae and Tiryns were excavated by Dr. Schliemann. He dug also at Orcho- menos, in Bceotia, where the work was resumed last spring by Pro- fessor Furtwangler, of Munich, who found interesting objects of a very early age, including specimens of the same early (non Greek, non Phoenician, non Egyptian, non Assyrian, non Cyprian) writing which covers thousands of tablets discovered in the palace at Cnos- sus, in Crete. The temple of L,ycosura and its surroundings, which was called by ancient tradition the oldest town of Peloponnesus, has been excavated by the Greeks. The site of Corinth is in process of excavation by the American School. At Athens more or less archeological digging has been done since it became the capital of the new Greek kingdom, from 1834 on. Gradually the summit of the Acropolis has been cleared of rubbish and from buildings of the Frankish and Turkish times, and the im- portant structures on its slope — the Theater, the Odeum of Herodes Atticus, the Asclepieum and the Stoa of Eumenes — have been either brought to view, as the Theater and the Asclepieum, or have been cleared, as the Odeum. In the city of Athens systematic excava- tions have been difficult or impossible. When the seat of govern- ment was fixed there, seventy years ago, the site of the ancient city was covered by the Turkish town. Low, mean houses these were, and little money would have been needed for the purchase of a large district ; but the Greeks then had no money to expend for archeo- logical purposes. If modern Athens had been built at the Piraeus, as some urged on other accounts, the solution of the archeological problem would have been easy ; but the value of the land in the city has increased about as rapidly as the Greek government's means for 226 CARNEGIE INSTITUTION excavations. A peculiar and unfortunate " squatter's law," together with the carelessness of officials, allowed to certain "squatters" rights to land immediately adjoining the Acropolis, which was not occupied when the Greeks returned to Athens and which never should have been used for buildings. These have been dispossessed, but no thorough and systematic examination of the soil of Athens has been practicable. The American School has conducted excavations at Eretria and Sicyon in addition to doing less important work on half a dozen other sites. The British School has excavated at Megalopolis, the French at Mantinea and Tegea. The Greek Archaeological Society has conducted important excavations at Thermon, in iEtolia, the capital of the iEtolian League, and at dozens of other places, the income of the only lottery authorized in Greece being given to this society to be used for excavations and for the care of the ancient monuments. In the year 1902 the Greeks conducted excavations in twelve or thirteen places in their own kingdom, in addition to beginning the work of laying bare the ruins of the great temple of Hera, at Samos, which is still tributary to Turkey, though on a different footing from Chios and Lesbos. Islands. — The islands of the JEgean sea have not been neglected either. The French have dug on Delos intermittently, and on Amor- gos, The British have dug on Melos. The Austrians explored Sa- mothrace. Freiherr Hillervon Gartringen has excavated what may be called a Greek Pompeii on the island Thera. Early in the nine- teenth century (181 1 ) slight excavations were made on iEgina at the time when the sculptures of the temple of Aphsea were removed, and within the last two or three years Bavarian archeologists have car- ried these excavations further. For two years a Danish society has dug on the island of Rhodes. Other excavations also have been made on these islands, but it would be too long to enumerate all of them here. Even Belgians here have entered the lists of excavators. Englishmen have explored Kos, and one of their countrymen spent several weeks this summer on Karpathos, exploring it, as is believed, with a view to the discovery and excavation of Mycenaean sites. Crete. — For many years archeologists have looked to Crete for the solution of many of their problems, and occasionally endeavored to explore it. About twelve years ago the Archaeological Institute of America organized an expedition for Cretan exploration, but the con- ditions proved more unfavorable than was anticipated, and the plan was soon abandoned. Naturally, then, when this island was brought CLASSICAL ARCHEOLOGY 227 under the protection of the Great Powers, and freed from the vexa- tions and uncertainties of Turkish rule, not a few — among whom Italians, English, and Americans were most prominent — were eager to begin explorations and excavations there. Several Italians had made themselves familiar with the island, and have dug at Gortyna, Phsestus, and Agia Triada, near the southern coast. At Gortyna, a town mentioned by Homer as " well walled," was found eighteen years ago the longest law code which has come down to us from ancient times — from about the middle of the fifth century B. C. — of particular interest because of the recognized high reputation in an- tiquity of the Cretan laws. This was one of the sites on which our Institution hoped to make excavations ten years ago ; but archeolog- ical exploration is not easy at this point even now, because of a water- course and mills which involve vested rights. At Phsestus the Italians have found the remains of a magnificent palace of the same period as that at Cnossus — not so extensive, but rather better pre- served and of equally impressive proportions. Agia Triada lies only about 3 miles from Phsestus. The excavations there are not com- pleted, but the ruins seem to be those of a nobleman's residence rather than of a palace, in the English sense. Twenty five years ago certain discoveries seemed to indicate the site of the old palace of Minos at Cnossus, 4 or 5 miles from Candia, on the northern side of the island. Dr. Schliemann at one time nearly completed arrange- ments for the purchase of the land and the conduct of excavations, but some new difficulty aro.se and the negotiations were broken off ; but as soon as the new government was established at Crete, Mr. Arthur Evans — a distinguished son of a distinguished father and the keeper of the Ashmolean Museum — who had long been waiting for this opportunity, with much patience and ingenuity in meeting difficulties and in overcoming them, purchased this land on his own account, and has there made the most brilliant archeological discov- eries of the last twenty years. Since the final destruction of the palace, perhaps 300 years B. C, its site has been uninhabited and even unfilled, so that in places the ruins were hidden by 110 more than a foot's depth of earth. Miss Boyd began her excavations in Crete at Kavusi, on the north- ern shore, in the name of the American School of Athens, with' part of the stipend received by her as fellow of that school. During the last two seasons she has dug at Gurnia, not very far from her former site, receiving her principal support from the "American Exploration Society," but using also her own limited means. She has found the 2 28 CARNEGIE INSTITUTION best example yet known of a "Mycenaean" village, with town chief's house, but no palace ; and with a town shrine, the first such to be known of this period, though at Cnossus earlier and later shrines have been fonnd in the palace. At Palaeocastro, near the eastern end of the island, Mr. Bosanquet and his associates have a Mycenaean town larger than Gurnia, but of no great splendor, though with very delicate and beautiful pottery. The cave of Dictaean Zeus has been explored by Mr. Hogarth. Less important excavations, like those at Zakro and Praesus, may be passed over here. Opportunities in Greece. Although excavations have already been made on the most noted sites and those which promised the surest and richest rewards for investigation, yet in Greece, too, interesting, important, and promis- ing sites remain almost entirely unexplored. I would name Thebes, the Miuoan promontory of Megara, Eiis, Sparta (including Amyclae), Gythion (the port of Sparta), and Samikon (near Olympia, on the west coast of Peloponnesus). I will write of these briefly in reverse order. Samikon is thought by some to have been the western terminus of a " trade route " through Peloponnesus, from Gythion on the east, a thousand years or so before the beginning of our era. Excellent "polygonal" walls lie on it, and no excavations have been made there. Satisfactory trial excavations might be made for $1,000, in my opinion. Gythion was not only the port for Sparta, but also the port for Amyclae, the older capital of the Eurotas valley ; and if ever a " trade route " crossed Peloponnesus, this must have been the great eastern terminus, whatever was the western. This site is urged for excavation not only by classical archeologists, but also by Mr. Flinders Petrie, who hopes that there will be found objects which will throw light on the relations between Greece and Egypt in early times. Eittle has been done in the way of excavations at Sparta, partly, no doubt, because of the improbability of finding great ruins. Thucydides says that in ages long after him men will hardly be ready to believe the former power of Sparta, while they will exaggerate that of Athens, judging from the ruins in each case. No one can hope to find a Parthenon or Erechtheum there, and no walls ever existed to be traced now, and no such mass of inscrip- tions as have been found at Athens was ever known in Sparta ; but CLASSICAL ARCHKOLOGY 229 many indications may be found of the early life, history, and institu- tions of the Spartans, and perhaps of their predecessors. Long ago C. O. Midler suggested that the real home of the Pelopids was to be sought at Amyclae rather than at Mycenae, and not a few indications point to this conclusion. Near Amyclae have been found golden cups, ornamented with scenes of the bull hunt, in " Mycenaean" style, of an advanced type of art. Since the Cretan excavations and the discovery of the " Mycenaean " culture there, archeologists are eager to ascertain where this civilization was developed. On the discovery of the palace at Cnossus, many were disposed to regard this as the chief center of the " Mycenaean " art and life, but now some archeologists are disposed to turn their eyes back to Greece as the original home of this civilization, and since Argolis has been explored — at Mycenae and Tiryns — the chief new light for this question, from Greece proper, must be expected from the region of Amyclae. Elis was the chief town of Western Peloponnesus, and almost nothing has been done as yet to explore its site. This name has come first to the lips of two or three archeologists when they were questioned as to the opportunities for excavation in Greece. The very name of Minoa, at the harbor of Megara, reminds one of Minos and Crete and the Phoenicians. A recent ingenious writer counts this as the beginning of a Phoenician trade route through Boeotia, and, though we may not believe the Phoenicians to have had so strong a footing in Hellas as Berard's theory implies, this Minoa is indicated as one of the landing points and trading ports of the Phoenicians, and thus as one where remains might be found which would throw light upon the early relations between the east and the west. Thebes was the center of a large body of myths and poems. In the fourth century B. C, before its destruction by Alexander the Great, it had 30,000 or 40,000 inhabitants. After its restoration it may have had 10,000. At present it has only some 4,000 or 5,000 inhabitants, and occupies but a part of the old Cadmea, and fewer remains of antiquity are left above ground there even than at Sparta. The excavations which have been made there seem to afford perfect confirmation of the supposed myths as to the age and early influence of the city. Confirmation of the story of its connection with Phoe- nicia remains to be given. On the whole, I am disposed to recom- mend this site for excavation rather than any other in Greece, particu- larly since the railway from Athens to Thessaly, which has already 230 CARNEGIE INSTITUTION been completed into northern Attica, is to be extended at once to Thebes. This is sure to stimulate the rapid growth of the city as the center of a very fertile plain ; the price of land is sure to rise rapidly, and the experience of Athens is likely to be repeated there — houses will be built over the remains of ancient Thebes, and system- atic archeological excavations will soon be put out of the question. A further consideration in this connection is that the digging of the navvies for the railway is sure to bring to light much material and many facts which would be of high value when combined with those secured by the archeological explorations. I should like to write in detail with regard to the American exca- vations at Corinth. These are the most important archeological excavations in progress at present in Greece, and the)7 have received marks of higher appreciation from archeologists abroad than from the public at home. Those who complete this work, naturally, will receive the credit of it, and others would be very glad to continue the explorations there, if the American School is obliged to abandon the site. European archeologists believe the results attained at Corinth to be large in comparison with the sum expended, which to the pres- ent time I suppose to be about $15,000, which is only a fifth of that expended at Ephesus, yet with as important scientific results. Exca- vation is not the chief work of the American School at Athens, and money for this work at Corinth has been secured with difficulty. Opportunities in Crete. In Crete, Miss Boyd's work certainly ought not to be allowed to end before she considers it completed. She has achieved important results with small means. She could not have done what she has if she had not paid a large part of her own expenses and found helpers who were ready to pay theirs. At Gurnia, last May, Dr. Dbrpfeld spoke highly of her work, but after the party reached the steamer he called the company together and said that he should have spoken more highly of the excavations on the spot if he had not understood that it would be distasteful to Miss Boyd, who was present ; her work "could not have been better done." Her explorations at Gurnia are nearly completed. She would be glad, however, I am assured, to make a thorough exploration of the route which passes that town, from the northern to the southern shore of the island. This route is only about 10 miles in length, and seems to have been used in very ancient as well as in modern times ; it was used as a CLASSICAL ARCHEOLOGY 23 1 ' ' portage ' ' by the French troops at the time of the recent military occupation of the island by the Great Powers. What support Miss Boyd is likely to receive from the society which has furnished her a small sum of money (I think only $2,000 this past year) for the work of i90i-'o3, I do not know. Such explorations can be most econom- ically administered with a larger sum of money to expend. As for Miss Boyd's personality, I may say that she graduated at Smith College about 1 2 years ago, and is now instructor in arche- ology in that institution. In the year 1 896-' 97 she was a student in the American School at Athens, and was preparing to enter the com- petitive examination for a fellowship of the school. On the outbreak of the war with Turkey, however, she went with several Athenian ladies as a volunteer nurse to the hospitals of Thessaly, where she attracted much attention because of her unusual "capacity." In a later year she entered the fellowship competition which she had abandoned in the spring of 1897, and was successful. At the expi- ration of the year of her first fellowship she was appointed Hoppin fellow of the school, with a stipend of $1,000, half of which she used for her first excavations at Kavusi. Her life in Thessaly aided to give her an excellent command of the Modern Greek language, and brought her into touch with the Greek people in a way which has been useful to her in Crete. I should add that her reports of her explorations are admirably clear and methodical. The suggestion has been made that America might join with Mr. Evans in his work at Cnossus, but he has nearly accomplished his great task. The great palace has been uncovered. It is true that an earlier palace lies in ruins under those of the later palace, and he will run some tunnels next year to learn what he can of the earlier without disturbing the later structures, but his work is substantially completed. As for fresh sites of excavation in Crete, almost nothing has been done for the exploration of the western end of the island, which we may suppose to have stood in the closest relations to the peoples on the mainland of Greece ; but no site there seems to be preeminently attractive, and a careful archeological survey and exploration of the island seems wise before further excavations are made, though such an exploration might discover almost at once a particularly attractive site. A French survey of the island under Ardaillon was planned a year ago, but I have not learned that it has been actually undertaken. 232 carnegie institution Laws as to Exports of Antiquities. The time is past when private or public museums can be enriched with works of art and curiosities by excavations. These now have to be conducted on a more ideal basis, for the advantage of the science of archeology and not as a commercial speculation on the part of the digger. In retired districts of classical lauds some of the inhab- itants have had much experience in finding and opening tombs for the sake of the treasures or trifles which were buried with the dead, and think this occupation to be more remunerative than agriculture ; but all exportation of antiquities from the lands of ancient culture is now contrary to law. At the opening of the nineteenth century, when Greece was still in the hands of the Turks, Lord Elgin, by gifts and diplomatic arts, secured permission to "draw, model, re- move, and excavate" any of the old buildings at Athens, and made large use of the right to remove, taking all that he wanted of the sculptures of the Parthenon, the frieze of the temple of Unwinged Victory, one of the Caryatids, a column and a long piece of the frieze of the Erectheum, the statue of Dionysus from the choragic monument of Thrasybulus, etc. Not much later, in 181 1, two young Englishmen and two Germans stole the sculptures from the temple of Aphsea on ^Egiua, which are now the chief ornament of the Glyptothek, in Munich, and in the next year the same party, with one or two more, by a heavy bribe persuaded the Vizier of Pelo- ponnesus to allow them to remove the sculptures from the temple at Bassse, which were sold to the British Museum for ^60,000. Mr. Hamilton Lang conducted excavations for antiquities on Cyprus in 1870 during two months without a firman from the government, and the sculptures are in the British Museum. About the same time General di Cesuola opened hundreds of tombs before he was obliged to seek the permission of the government ; then he obtained a firman for the excavations which furnished the treasures for the Metropoli- tan Museum. Probably under the influence of the Cyprian excava- tions, attention having been called to the value of antiquities, Dr. Schliemann, in 187 1 , was obliged to promise to give to the Turks a share of the objects found by him at Troy, and difficulty was made in renewing the firmans. He conveyed away the most splendid of the gold treasures found at Troy, but later gave to the Turkish gov- ernment $10,000 for its share of this treasure. From 1863 to 1874 Mr. J. T. Wood, an English architect, was engaged in excavations at Ephesus. He was allowed in 1863 to export all antiquities which CLASSICAL ARCHEOLOGY 233 he might find, leaving the duplicates for the Turkish government ; but in 1872 he reports that the Turks were disposed to grant no more firmans for excavations ; they would do this work themselves. The Germans, however, were allowed to excavate on the site of Pergamon, beginning in 1878, on condition of giving to the Turkish govern- ment one third of the objects discovered, which third they later were allowed to purchase. The Americans were allowed to excavate the site of Assos (1879-1881), giving to the Turks one half of the objects found ; and the Austrians were allowed to remove the sculptures from the Heroon of Gjolbashi, in Eycia (1 881-1883); but these seem to have been the last firmans for excavation in Asia Minor granted by the Turkish government that include the right of ex- porting the objects found, or any considerable number of them. Excavations in the interior of Asia seem to be on a slightly different footing. One of the first acts of the newly established Kingdom of Greece in 1834 was to forbid the exportation of antiquities. The Greeks had been humiliated and exasperated by the removal of the ' ' Elgin marbles," which was followed soon by the abstraction of the sculpt- ures from iEgina and Bassse, and their government saw clearly that it would be mischievous to allow to pass freely from their country the memorials of their country's nobler past, and that not only pro- fessional scholars, but also other visitors, might be drawn to Greece for the sake of seeing its antiquities. The law was far in advance of public sentiment, however, and its influence has not been alto- gether beneficial. Men of learning and high position, professors in the University of Athens, not only connived at such smuggling, but were believed themselves to be dealers in antiquities to be delivered to the purchaser outside of Greece. I have myself known a man of distinction to amuse himself with outwitting the Greek custom house officials and conveying antiquities out of the country. Discoveries of antiquities, instead of being announced at once, were generally concealed, that the finds might be the more easily carried or sent from Greece. Thus the circumstances of the discovery, often of greater scientific interest than the object in itself, were concealed or passed unnoticed. Not infrequently also objects too large to trans- port easily in secret, such as statues or stelae, were broken, and the large number of heads of terra cotta figurines without bodies offered for sale has been explained by the disposition of the finder to save only what he could most easily keep for himself. The mass of an- tiquities, large objects as well as small, which have reached the 16 234 CARNEGIE INSTITUTION museums of Europe and America from Greece in the course of the last seventy years is sufficient evidence that the Greek law against exportation is often evaded, and the efforts to elevate the public sen- timent on the subject have not been very successful. The peasants in general do not yet understand why their government or any one else should care for broken stones or old pottery, and if strangers are disposed to pay a good sum for these trifles, why should they not have them ? The Greek senate has recently passed a much stricter law, making every work of antiquity, wherever or however found, in Greece or in Greek waters, the property of the state, if this cares to take it for its museum. In this case the finder is to receive from the Archaeological Society half of the value of the article. Every official of the government is bound under heavy penalties to see this law enforced. For dereliction of duty he is liable not only to be deprived of his office, but also to be sentenced to fine and im- prisonment for two years. But very recently a party of archeolo- gists visiting Eretria brought away with them vases that, in my opinion, were not only more numerous, but also more valuable, than those in the Eretrian Museum, all purchased within a few feet and almost under the very eye of the soldier on duty as a policeman. Though it is only fair to add that the best vases from Eretria were already in the museum at Athens, yet the letter of the law was fla- grantly violated in the sale to the archeologists. Contrast with Former Spirit. The Turkish government in 1884 enacted a similar law to that of Greece, absolutely forbidding the exportation of antiquities; but this law, too, is not supported by public sentiment, and the exportation continues, though attended by difficulties. The European or Ameri- can purchaser is obliged to pay a higher price because of the increased risk to the seller, and the high price in turn encourages illegal digging, and thus leads to archeological loss. The Germans, on renewing their excavations at Pergamon, receive for themselves only the objects that are needed to complete those which they removed to Berlin a score of years ago. The great Museum of Cairo is already provided with a large supply of the ordinary objects found in Egyptian tombs, but the law for- bidding the export of antiquities, except such as are derived from authorized archeological excavations, is so strictly enforced that a prominent dealer in antiquities has recently given up his business, it CLASSICAL ARCHEOLOGY 235 being no longer profitable. A movement has been set on foot lately to forbid the export of any antiquities from Egypt, but this law is thought unnecessary, since the present statute virtually allows the Museum at Cairo to select what it wants from the objects found by the explorers. One of the first acts of the new Cretan government was to enact a law similar to that of Greece, but still more stringent in its provisions. No antiquities may be exported from the island except those that are registered as such, with many formalities, on their exportation. The sentiment of the people on the subject is said to be good. Foreign excavators there pledge their word of honor that they will not convey from the island any of the objects which they find. In all lands, however, the right of first publication is reserved for the excavator or finder. Thus all future excavations in classical lands are to be conducted on the ideal basis — not for spoils, but for science. Twenty five years ago the Germans were called sentimentalists for undertaking the excavations at Olympia for the Greeks with the agreement that they should receive for themselves only duplicates and the right to make casts and photographs, and it was thought that they would have but few successors. Ten years later, however, the French proposed the excavations at Delphi without asking even for duplicates, if there should be any such. And the strictness of the Greek law has not checked the desire of foreign nations to take part in this work of uncovering the monuments of the past. The motive in archeological excavations today is in marked con- trast to that which prevailed in former times. Men have always been aware that objects of more or less value were often or generally buried with the dead, frequently, no doubt, in the belief that the spirit of the dead would be able to use or enjoy them in some way, and again often merely as a tribute of affection, just as flowers are laid upon a grave today. Men have been tempted from time imme- morial to open tombs and to take whatever they could find there for their own use, though the act and the occupation of a grave robber were despised. Thus in some districts the majority of ancient tombs were opened and plundered in early times — many centuries ago. Of thousands of sarcophagi in Lycia, not one has been discovered in modern times which had not been opened previously. In other lands less of this work had been done in antiquity. A few years ago, according to report, three thousand Bceotian tombs which had not been robbed previously were opened by the country people before 236 CARNEGIE INSTITUTION the interference of the government, in the search for terra cotta figurines, which already were bringing a high price in the market, though not so high as at present. In the fourteenth, fifteenth, and sixteenth centuries of our era, with the new interest in ancient literature was awakened also interest in the monuments of antiquity, particularly in works of ancient sculpture. Much digging was done in the neighborhood of Rome, on the sites of ancient villas, and many statues were brought to light. These were valued chiefly for themselves, however, as works of art, and if (as almost always) they were broken they were "re- stored " according to the ability, taste, and caprice of their owners. No one shrank from adapting the head of one statue to the body of another, if these could be made to fit by changing one or both of the parts, nor would the owner hesitate by an alteration of attribute to make a muse into an Artemis or a Demeter. This method of deal- ing with objects of antiquity continued until recent times. They were considered more valuable when "perfect," though the perfec- tion were the result of a "restoration." Early in the nineteenth century the statues from the pediments of the temple of Aphsea on ^Egina, having been purchased by the crown prince of Bavaria, were entrusted to the sculptor Thorwaldsen, who " restored " them most carefully and conscientiously, but archeologists now regret that they were "restored" at all. Canova deserves and receives credit for declining to add arms and noses and heads to the ' ' Elgin marbles ' ' from the Parthenon at Athens, when this was suggested. But only a third of a century ago most men of culture were not shocked — only a few archeologists were troubled— at the thought of a " resto- ration ' ' of the statues found on Cyprus. The proper treatment of broken works of art, I may say parenthetically, has never before been exemplified so well as in the French treatment of the sculptures found in the recent excavations at Delphi, shown in the museum opened there last May : the broken marbles are set up as nearly as possible in their proper positions and relations, with no additions, while near them are placed plaster models with the missing parts restored ac- cording to the judgment of the archeologists and artists in charge. The early expeditions for archeological purposes were insuffi- ciently equipped, and thus desire for objects to fill museums appears as their exclusive aim. Even only thirty or forty years ago the " science of the spade" was in its infancy. Fr. L,enormant pub- lished in 1862 the results of his Recherches archeologiqucs at Eleusis two years before ; but he has nothing to say except about the inscrip- CLASSICAL ARCHEOLOGY 237 tions which he found there. Wood conducted excavations at Eph- esus for more than ten years, but not as an archeologist. His aim was to find the great Temple of Artemis, and he cared little for the instruction afforded by the smaller objects which might be found in the course of the excavation. Few of these smaller objects came into his hands. They seem to have been considered a sort of perquisite of the workmen. He had not learned that a small object may be quite as instructive, though not so imposing, as a large object. During a large part of his excavations Wood was busy in his vocation as archi- tect at Smyrna, and his explorations at Ephesus were left entirely in charge of his foreman, who laid not even the slightest claim to archeological knowledge, but was chosen simply for his skill in keeping the laborers at their work. Similarly Schliemann under- took his excavations on the hill of Hissarlik with no archeological preparation or associate. He dug at first simply to prove the truth of his theory that the hill of Hissarlik was the site of Homeric Troy. He put his first great trench 40 feet deep and broad in proportion through the upper part of the hill, exactly as a railway contractor would make similar cutting for his tracks. He had at work 150 men with barrows and carts, but not a single archeologist to watch or to advise. Of course some irreparable damage was done by the destruction of ruins in the upper strata with no adequate observa- tion and record of them. After finding the great treasure of gold at Troy in 1873, and, still more, after discovering the wealth of gold array in the tombs of Mycenae, Schliemann dug both as a treasure seeker and to prove the truth of his theories, but hardly as an arche- ologist. He seems to have been disappointed at not finding gold at Tiryns, and to have been disposed to consider his excavations there a failure until scholars of all lands declared his architectural discov- eries to be more valuable than a mass of gold. At Mycenae his in- terest in the treasures of the tombs was so overpowering that he took small pains to preserve the tombs themselves and allowed a con- siderable part of the ' ' sacred circle " to be destroyed. But he learned to excavate by excavating, and attained considerable archeological knowledge and skill. To him more than to all other persons is due the extraordinary interest in modern archeological excavations, but his work had no scientific character, in the modern sense, until 1882, when he secured the cooperation of Dr. Dorpfeld. General di Cesnola, too, in digging in Cyprus, had had no more archeo- logical training than Schliemann, and a large part of his work (according to current report) was done for him, like the excavations 238 CARNEGIE INSTITUTION of Wood at Ephesus. These men achieved important results, but in considering their work we must bear in mind that they were not archeologists at the beginning ; they learned their trade by prac- ticing it — by many costly experiments. Now all this method is changed. In the last excavations on the hill of Hissarlik Dorpfeld employed only one seventh as many common workmen as Schlie- mann had set at the big trench, and had with him three or four trained archeologists to observe, direct, and study. In Egyptian explorations pains are taken to allow no scarab to be lost. Of slight ' ' museum value ' ' in itself, any such may supply the clue for the solution of some problem. In the excavations of Flin- ders Petrie in Egypt last winter, one object considered worth all the rest was a little image of the old king Khufu (Cheops), no longer than a man's hand, which would have escaped notice in excavations like Wood's. Modern archeological excavations are much more expensive than those conducted on the railway contractor's plan, but they are also much more instructive than those that were intended primarily to fill museums. Reinach, one of the most distinguished of French archeologists, in going a few years ago to dig at Myrina, in Asia Minor, where an indefinite number of terra cotta figurines had been found, said expressly that the expedition had as its first object not the finding of figurines, but to learn what was possible of the burials and the ancient life at Myrina. Now that the temptation to dig simply for objects of antiquity is removed by the law which forbids their exportation, archeologists are free to explore simply for the sake of science. Mrs. Hearst, of California, be it said to her praise, has given this direction to the party under Dr. Reisner which is digging at her expense in the soil of Egypt ; they are to do what is best for the science of Egyptology, without regard to showy dis- coveries. In another respect, too, the archeological excavations of the pres- ent differ from those of the past. Fifty years ago no one planned to lay bare the entire site of a sanctuary, and still less that of a town. Even at Pompeii until 1861 the excavators chose what seemed to be a promissing place here, and another there, as if they were picking blackberries in a mountain pasture. There, too, naturally enough, more attention was paid to the objects found than to what might be learned from the position of the objects, and after the antiquities had been removed to the Naples Museum no sufficient care was taken of what had been uncovered, but left, at Pompeii. Naturally, too, Wood's excavations at Ephesus were entirely un- CLASSICAL ARCHEOLOGY 239 systematic. In order to find the great temple there he sunk trial pits for six years before he identified the sacred precincts, and dug for three or four months longer before he found the temple itself. More systematic digging would have found the temple sooner. And when he had found the temple, deeply embedded in a marsh, he dumped a considerable part of the earth which he removed from the temple upon the spot where we may believe the great altar to have stood. So the British Museum plans this year to resume those old excavations and to complete them according to modern methods. Similarly, at Delos, the French excavated buildings here and there, leaving between them in many cases spaces of unexcavated ground, with the result that the visitor has no connected view of the sacred precinct of Apollo as a whole. Here, too, because of the lack of a systematic and generous plan at the first, much of the earth has been moved twice, and part of it, I am told, three times. That the French expect to resume these excavations this year I have already stated. The early parties for the conduct of excavations and explorations in many cases were not well equipped with specialists, though these generally were not entirely lacking, as they were in the cases of Schliemann, di Cesnola, and Wood. The French seem to have been the first to send out companies for the purpose of investigating not only the "antiquities" and monuments of the country, but also its topography. The American excavations at Argive Harseum had a trained architect, but such a specialist is needed urgently also for the American excavations at Corinth, and has been needed in a less degree in the minor excavations as at Eretria and Sicyon. Present Excavations in Greece. At present excavations on Greek lands are carried on as follows, in addition to several minor excavations of the Greeks themselves : Corinth : The American School at Athens. Argos : Mr. Vollgraff , supported by a Hollander. Tegea : To be resumed by the French. Pergamo?i : The German Institute, under Dr. Dorpfeld. Ephesus : (The Temple of Artemis.) Resumed by the British Museum. Ephesus: (The City.) The Austrian Institute. Miletus : The Berlin Museum, under Dr. Schrader. 240 CARNEGIE INSTITUTION Crete : Cnossus : Mr. Arthur Evans. Palceocastro : The British Society for the Promotion of Hellenic Studies. Gurnih : Miss Boyd. Agia Triada : The Italians, under Dr. Halbherr. Samos : The Greek Archaeological Society. Rhodes : The Danes. Delos : To be resumed by the French. Leucas : Dr. Dorpfeld, supported by a Hollander. Summary of Advice. To sum up what has been said with regard to the opportunities for archeological research, one cannot easily, briefly, and safely com- pare the advantages of different sites. Between general exploration and excavation the balance might be turned by the possibility of forming a better party for one or the other sort of work. Corinth I regard as exceedingly important. Miss Boyd has done and is doing admirable work at Guraia. The archeological exploration of the western end of Crete and of Asia Minor would be of real scientific value. The sites of Antioch on the Orontes, Laodicea, and Boeotian Thebes seem to me on the whole to be the most promising for a great excavation. Neither of the first two of these should be under- taken without the expectation of spending at least $50,000. Valu- able work could be done at Thebes for less, although the sum named (to be expended in five years) would not be too great for thorough explorations there. A much smaller sum, perhaps $5,000, would suffice (so far as we can judge) for the exploration of the Minoan promontory of Megara and for trial excavations at Gythium, the port of Sparta. An exploring expedition to Asia Minor or to Crete should be dispatched, not for a single season, but for at least two. Three seasons would be still better. Classical Archeology Worthy of Support. Perhaps I may be allowed to add a few words with regard to the appropriateness of the work of archeological exploration in classical lands under the care and with the help of the Carnegie Institution. (1) Classical archeology is now a science, and one in which many young scholars of our country are interested. For the most success- CLASSICAL ARCHEOLOGY 24 1 ful study of this science, a direct and intimate acquaintance with the objects of antiquity is necessary. Laboratory work is as important in the pursuit of this science as for either chemistry or physics. The best practice is secured by fresh material, which rouses the student who is engaged in research to the fullest use of his powers, and this new material is secured best by excavations, the privilege of first study and publication being always reserved for the excavator. At the present stage of the science such material is peculiarly impor- tant, and our scholars are handicapped, as compared with others, if they are not provided with it. The science of classical archeology is important in itself ; it may stand alone ; but as a subsidiary to the study of ancient history and philology it deserves special con- sideration because of its relation to general education. The ancient histories of a few years ago have little more actual value than the chemistries and geologies of the same time, and the advance in our knowledge of ancient history is due primarily and principally to the work of archeology. And from all other sources combined, ancient literature — biblical and classical — has received, I think, less light within the last third or half of a century than from archeology. (2) Our relations to classical archeology are peculiarly close, since this is our source of information with regard to the earliest culture from which we can trace our own. America rightly feels the special obligation to learn what can be known with regard to our predeces- sors on the western continent, but our modern life has been influenced to no appreciable extent by the habits and deeds of the North Ameri- can Indians. Our intellectual inheritance has come from the Greeks and Romans, to whom we stand in the same relations as do our English and German cousins. All the learning and devices of Egypt and the farther East have not affected us directly. The history of our alphabet may be taken as an illustration. The Phoenicians traded with all the peoples of the Mediterranean and the Black seas — very likely even with the early inhabitants of Britain — but not one of all these peoples except the Greek had the skill to adapt the Phoe- nician alphabet to western use. Thus also Egyptian mathematics and Chaldean astronomy were received by the West only after being digested and assimilated by the Greeks. Still less did Egyptian and Assyrian art influence directly our own sculpture and archi- tecture. Sir Henry Maine exaggerated only slightly when he said, "Everything that is not a law of nature is in its origin Greek." Since we are the intellectual descendants of the Greeks and Romans, and claim this relationship, the study of their lives and works is as 242 CARNEGIE INSTITUTION fitting for us as for any other moderns, and we might as reasonably leave the science of astronomy or that of mathematics to the other nations of the world, sure that it would not be neglected though we did not pursue it, as to leave to the peoples of Europe the advanced study of classical archeology and philology. Our manner of life and our literature are so founded upon those of the ancients that we cannot properly understand the present without an appreciation of the past. Largely through the opportunities offered by the American School of Classical Studies at Athens and its sister school in Rome, about two hundred of the classical teachers of our country have been brought into direct relations with the antiquities of Greece and Italy. We have as yet, however, only four or five classical archeologists who in training and attainments are worthy to be classed with the European university teachers of archeology. Work in connection with an important excavation or an expedition for exploration would do much for the training of the men who are to be the leaders of the science in America and who, we hope, will advance the whole science of classical archeology. London, September i, 1903. MECHANICS OF THE HUMAN VOICE Report by E. W. Scripture. CONTENTS. Page Introduction 243 Methods employed 243 Problems attacked 245 Results obtained 248 1 . The nature of vowels 248 2. The melody of speech 253 3. The rhythm of speech 254 Continuance of the work 255 Introduction. I have the honor to report on a grant of $1,600 for prosecuting researches on the voice. As stated in the original application, I had on hand a large amount of unstudied material accumulated by a new method. The method consisted essentially in registering the human voice by the latest gramophone apparatus, and then tracing off the vibrations in great enlargement by a machine which I con- structed specially for the purpose. This method has the advantage over all other methods of studying the voice by preserving the original speech as a gramophone plate (or phonograph cylinder) as well as furnishing the curves. Methods Employed. Two quite distinct kinds of activity were involved, namely, ob- taining the curves and studying them ; the organization therefore included a tracing station and a computing bureau. At the tracing station the curves are obtained from a gramophone plate — selected or specially made to contain any desired vocal utter- ance— by tracing off the vibrations by a special machine. Such a machine is suspended by springs or placed on a cement floor in a rather long room (50 to 100 feet). The machine is run continu- ously by an electric motor. The curves are traced on long bands of ;smoked paper ; the speech curve appears as a thin white line on a (243) 244 CARNEGIE INSTITUTION black surface. On account of its delicacy, the machine requires daily- inspection and care by a mechanic. The renewal of paper occurs once every 12 or 24 hours, according to the length of the strip of paper, a factor that depends on the length of the room. Each re- newal requires work for 1^ to 2}4 hours. The strips of paper are varnished before they are removed from the machine. A narrow band containing the curve is then cut out and mounted in the form of plates on pasteboard. Each plate is covered with a sheet of celluloid and is delivered to the computing bureau. The records referred to in these investigations had been traced off by an apparatus known as Machine A. This machine was allowed to run at Yale University till March 1, at which date it was dis- mounted and turned over to the university. Owing to the fact that it was the first of the machines constructed, it could be successfully used only under my constant personal supervision ; owing to the many changes in its construction and to the wear of four years running (often day and night), it had become somewhat deteriorated. It was decided therefore to build two new machines on principles learned by previous experience. These are now finished. One, known as Machine D, has been at work at Yale University under care of the mechanic who built it, and has completed the tracing of a plate containing a record of Dr. S. Weir Mitchell's voice. The other, known as Machine C, was finished in Europe and is about to be set up in Berlin. Still another machine, of a different kind, had been constructed by a grant from the Elizabeth Thompson Science Fund several years ago. It traces off curves from a French phonograph with celluloid cylinders. Forty special cylinders of French prose and verse were made for it in 1902. It ran constantly from October, 1902, to May, 1903, and furnished the first curves of French speech ever obtained. These curves can be used for solving the problems of French vowels, French melody, and French verse, just as the curves for English were used for the problem of English speech. I have with me the complete tracing of a record of Lc Roi d1 Yvctot. It awaits funds for assistance in measurement and time for study. The work of the tracing station was carried on at Yale University until September 15. At the computing bureau the first work consisted of measuring abscissas and ordinates of the curves on the plates and in com- puting results according to certain formulas and methods. The MECHANICS OF THE HUMAN VOICE 245 methods of computation employed by other investigators were first tested and found to be not fully adequate ; they were therefore somewhat altered and developed and the approved methods were then applied to the plates on hand. A large amount of material had been collected during two years' work of the tracing machine. This could not be studied because the measurements and computations required so much time. It was decided to concentrate the effort at the start on this material. It was found quite impracticable to carry this out at New Haven, one reason being the difficulty of securing intelligent labor at small rates. I therefore located in Munich, hired work rooms, and ob- tained labor by advertisements. Any number of doctors of philoso- phy, university students, and retired army officers could be found at 10 to 15 cents an hour, graduates of the Realgymnasium at 7^ to 10 cents, scholars from the Realschulen at 7^ cents. The great number at disposal made it possible to select specially reliable ones. As many as fifteen persons were employed at one time. The control of these persons, the systematization of the work, and the checking of results were placed in the hands of a retired Prussian major, the Baron von Hagen, at 25 cents per hour. The organization was developed with German minuteness. Each piece of work — for example, the analysis of a wave — was kept in a separate little book ; each worker had his particular task, and the books were passed in order from one to another. Every item of work was signed by the worker ; when mistakes were found the person at fault was discharged. The separate books — nearly 500 in number — were classified and inserted in larger holders, from which they could be assigned systematically for working up any problem. A card index showed the progress and the material on hand. The analysis of a single wave of a vowel usually required a mini- mum of 5 hours' measurement and computation. The study of each hundred waves from various vowels thus required at least 500 hours. The measurement for the melody of a single four line stanza of verse required the time of one person for 6 hours a day for three weeks. The work of this measuring and computing bureau was carried on at Munich until October 1, 1903. Problems Attacked. The great amount of material accumulated comprised records of Continuous prose speech and verse in English and German ; they are 246 CARNEGIE INSTITUTION the first of their kind ever obtained, other investigators having con- fined themselves to single vowels sung into the apparatus (Hermann, Pipping, Bevier) or to single spoken words (Pipping). Since the entire impression that passes by the voice from speaker to hearer is contained in vibrations of the air at the mouth of the speaker, the curves of speech can be assumed to contain solutions for all the problems of vocal expression. Among these problems are the following : 1 . To determine the essential characteristics whereby one part of speech is distinguished in general from another — for example, the vowel a from the vowel c ; or, briefly, the acoustic nature of speech sounds, particularly of vowels. Do the vowels consist of tones from the vocal cavities that have fixed pitches (Helmholtz, Hermann) or may they be of any pitch, provided they have fixed relations of pitch among themselves (Lloyd) ? Are the resonance tones of vowels re- lated to the tone from the vocal cords as overtones to a fundamental (Helmholtz) ; or do they have no such relation (Hermann) ? If the latter is true, what is the explanation of such an apparent physical impossibility (Rayleigh) ? Are previous investigators right in look- ing for the essentials of a vowel in the resonance tones alone ? Why is the prevailing view of the nature and action of the vocal cavities inadequate to explain the thoroughly established results? 2. To investigate the rise and fall of the voice during speech — briefly, the characteristics of the melody of speech. In song the melody is apparently of a very simple nature ; in spite of its use for emotional expression, the melody of song cannot convey all the shades of feeling that are possible by the melody of speech. This melody differs for every condition of mind, for every person, for every dialect, for every language. What are its fundamental laws? 3. To investigate the characteristics of rhythm in prose speech. Both prose and verse have their elements arranged on more or less regular systems in respect to stress, duration, melody, and other elements. A complete study of these elements for verse would solve the problem of the nature of verse. The theories hitherto proposed were established on the basis of judgments by the ear alone, and they certainly all quite miss the essentials of the case. They are theories of verse as it appears in type rather than of verse as it comes from the mouth of the poet. 4. To establish the types of American vowels. There are not 10 or 12 typical vowels, as often supposed, but more nearly a hundred of them, as distinct and as indistinct from each other as the races MECHANICS OF THE HUMAN VOICE 247 of men. Some approach to the truth has been reached by lexicog- raphy in respect to the long vowels, but its results are largely erro- neous in respect to the short ones. Both phoneticians and lexicog- raphers are misled by spelling, and, by a well known psychological prejudice, vowels that are physically quite different appear to the ear as the same, and vice versa. For example, most phoneticians distinguish two forms of the so called indefinite vowel. Sweet (Axford) has lately recorded seventeen forms. In my curves I find several hitherto unrecognized forms, physically quite distinct, for nearly every vowel. 5. To study the differences of speech among various dialects. The phonetic survey of France (Guilleron) consisted in recording by ear the pronunciation of certain typical words in each district of France. The results were published as a series of maps, each one containing in phonetic type the pronunciation of the word at each place. The ear loses most of the differences in pronunciation ; the type loses still more ; the results are vague. The proper method would be to take records by the phonograph or the gramophone (as recently done by the Vienna Academy of Sciences for certain Bra- zilian dialects), and then to trace the curves by my method for accurate study. I find that phonograph records could be made with indestructible metal matrices and cylinders cast and delivered at a smaller cost per word than the atlas of Guilleron. Instead of maps with phonetic type, the student would have a collection of the speaking records. Various disappearing and changing languages (American Indian, for example) might thus be collected and pre- served. The records might then at any time be traced off and studied by the methods used in these researches. 6. To determine the differences due to the speaker or singer him- self, and to investigate the influence of training on these differences. 7. To investigate the influence of the emotions on the voice. These last two lines of investigation would lay the foundations for the psychology and physiology of vocal expression. It would lead to data concerning the laws of expression in vocal music and in oratory ; also possibly to the use of vocal records for determination of mental conditions in health and disease. Of the work on these and other problems only the results for the first three will be considered in this report. 248 carnegie institution Results Obtained. 1. The Nature of Vowels. According to Helmholtz a vowel consists of the reinforcement, by the vocal cavities, of overtones in the tone from the vocal cords, these reinforced tones lying within definite regions for each vowel. Thus, for the vowel a the vocal cavity is so adjusted that it reinforces a certain tone ; this tone, however, as an overtone, must stand in respect to its pitch in one of the relations 1, 2, 3, etc., to the tone of the vocal cords ; that is, its number of vibrations must be an even multiple of that of the cords, and cannot be, for example, i}i or 4^ times as great. According to Hermann a vowel consists of the presence of a tone or tones of definite pitch, the pitch being quite independent of any tone or overtone from the vocal cords — that is, the vowel tone may have, for example, i^V or 5^f, as many vibra- tions, etc. The two theories agree in asserting the presence of tones of a definite pitch or range of pitch for a particular vowel ; thus for a there must be a tone of one pitch in the vocal sound, for 0 a tone of another pitch, etc. The two theories disagree as to the relation of this tone to the cord tone. Helmholtz based his theory on attempts to manufacture vowels by reed pipes and by forks, with results that were not satisfactory. Hermann based his on curves of vowels sung by his own voice into a phonograph and then traced off. The material in either case was extremely limited. The results now studied under this grant com- prised several hundred vowels by different speakers ; being curves of really spoken vowels, they required new methods of treatment and gave results quite different from the rather artificial vowels of song. It is to be understood that this work consisted of collecting speci- mens of speech of clearly evident excellence on gramophone plates, of tracing off the vibrations on paper in great enlargement, and of analyzing the waves of the curves by means of microscope measure- ment and mathematical formulas. Each single vibration of a vowel, for example, could be analyzed to show the set of tones from the cords and the vocal cavities. Each result stands as a fixed datum with which any theory has to reckon. The results soon showed that neither the theory of Helmholtz nor that of Hermann could be applied. No explanation or new theory could be found until a suggestion was received from another inves- tigation, as follows: MECHANICS OF THE HUMAN VOICE 249 The validity of a vowel theory can be tested by constructing an apparatus to produce vowels on its principles. The Helmholtz theory was tested by Helmholtz himself in his vowel apparatus. This consisted of a series of tuning forks with pitch frequencies in the relations of 1:2:3, etc. By adjusting the resonators different overtones could be reinforced. Helmholtz states that he could ob- tain only a good 0 and u. The same results can be obtained almost as well by simpler apparatus and in a way to refute the theory. Any well made tuning fork of any moderately low pitch will pro- duce a good u. Empty bottles often give good 11 vowels through several octaves of pitch. These facts made it unnecessary to con- struct another apparatus on the Helmholtz theory. I therefore began on the Hermann theory, which at the start I believed to be correct. According to this theory the vocal cords emit a series of puffs of air, each of which acts like a blow on the air of the vocal cavities and arouses the tones of the cavities. A blow of the hand on the open mouth will thus arouse the cavity tones. If we con- ceive the blow to be repeated often enough — e. g., 100 or 200 times a second- — we should hear a vowel. To produce these puffs of air I first used a siren comprising a disc with holes rotated before a blast of air. I found that a resonator with hard walls (brass, wood, etc.) would respond only when the puffs came at a definite pitch, whereas resonators with soft walls (cotton soaked in water, gela- tine, etc.) would respond to any pitch. I could thus produce good examples of a, 0, and ti with a siren tone of any pitch. I then tried a vox humana organ pipe with the same results. These vow- els were produced at any pitch of tone, as required by the Hermann theory. I utterly failed, however, to produce , Carnegie table at Woods Hole laboratory occupied by. xlv Report on grant to (Zoology), 1902-03 xliii McCormick, Mr. , Acknowledgment to 272 MacDougal, D. T., and Coville, F. V., Report by, on Desert Botanical Laboratory, Publication of 1 Report on grant to, for Desert Botanical Laboratory xxvi McGuire, F. B., Archeological work of, in caves of upper Potomac river. xvii Mach, Ernst, cited on establishment of geophysical laboratory 177 Magnetic Bureau, International, Correspondence regarding the project for 206-212 Funds required for 205 Method of work of 205 Organization of 205 Problems to be investigated by 203-205 Report on, by L. A. Bauer 203-21 2 Marine Biological Laboratory, Woods Hole, Mass., List of investigators occupying tables at, 1903 xlv Report on work at, 1902-03 xlv Marine Biological Station, Naples, Italy, Investigators occupying tables at xlvi Report on grant to, 1902-03 xlvi Mascart, E., Letter from, concerning establishment of International Magnetic Bureau 208-209 Mathematical works of George W. Hill, Publication of 1 Mathematics, Applications for grants in li Research Assistants in. . xlix 302 CARNEGIE INSTITUTION Page Maunder, E. Walter, Letter from, concerning Solar Observatory 160-164 Mechanics of the human voice, Continuance of investigation of, Esti- mate of expense of .' 255-259 Method of investigation of 243-245 Problems in, stated 245-247 Report on investigation of, by E. W. Scripture. 243-259 Results of investigation of 248-255 Medicine, Applications for grants in li Applications for grants in, declined li Medinsky, General, Acknowledgment to 273 Memorials : Marcus Baker lvii-lx William Earl Dodge lvi-lvii Abram S. Hewitt liii-lvi Mendenhall, C. E-, Letter from, concerning Solar Observatory I53_I54 Mercury, need for observations on 135 Meridian circle, Use of, for fundamental meridian observations 141 Meridian observations, Fundamental, Need for 112, 117, 121, 127, 128, 141 Value of 28-31 Merriam, C. Hart, Acknowledgment to 170 Merv, Ancient, Ruins of 279 Meteorology, Applications for grants in li Michelson, A. A., Report on grant to (Physics), 1902-03 xxxix Miletus, Archeological excavations at 239 Minerals, Production of, from aqueous solutions, Study of 179-180 Miscellaneous applications for grants, Number of li Mitchell, S. Weir, reelected member of Executive Committee xiv Moon, Motion of, Report on grant to Simon Newcomb, for determin- ing elements of xxi Need for observations on 135 Morgan, M. J. de, Work of, in Asia Minor 283, 284 Morosiewitsch, J., Experimental work by, in geophysics 179 Morse, Albert P., Academic training of xlix appointed Research Assistant xlviii Morse, H. N., Report on grant to (Chemistry) , 1902-03 xxx Mosquitoes, American, Report on grant to L- O. Howard for preparing manuscript and illustrations for monograph on xlii Mottier, D. M., Paper by, on fecundation in plants, Publication of 1 Moulton, F. R. , Collaboration with 261 Work by, on literature of origin of solar system 262 Mount Lowe, Character and amount of vegetation on 74 Double-star observations from 82-83 Location and character of 72 Mountain peaks near 92 Report on observations at 82-84 Seeing on 82 Tests on, for observatory site 73 Water supply on 73 INDEX 3°3 Page Mount Wilson, Advantages of, as site for observatory 75, 89-90 Fog on 91 Mountain peaks near 92 Ownership of land on 95 Record of tests for observatory site on 86-89 Vegetation on 75> 89 Water supply on 75> 89 Miiller, G., Letter from, concerning Solar Observatory 157-159 N Nalifkin, Madame, Acknowledgment to 273 Naples. See Marine Biological Station at. Neill, C. P., Academic training of xlix appointed Research Assistant xlviii Nelson, J. A., Carnegie table at Woods Hole laboratory occupied by. . xlvi Nernst, W., cited on establishment of geophysical laboratory 177 Neumayer, G., Letter from, concerning establishment of International Magnetic Bureau 207-208 Newall, H. F., Letter from, concerning Solar Observatory 165-166 Newcomb, Simon, Report on grant to (Astronomy), 1902-03 xxi New South Wales, Site for Southern Observatory in, Suggestions con- cerning 44 Nichols, E. F., Letter from, concerning Solar Observatory 146 Noguchi, Hideyo, Academic training of xlix appointed Research Assistant xlviii Noguchi, Hideyo, and Flexner, Simon, Results of investigation of poison of serpents by, Publication of 1 Noyes, A. A., Report on grant to (Chemistry), 1902-03 xxxi Nutrition, Report on grant to W. O. Atwater for experiments in xxxix Report on grant to Arthur Gamgee for work on physiology of xl Nymphsea, Monograph on, by H. S. Conard, Publication of 1 Nyren, M., Letter from, concerning Southern Observatory 127-128 o Observatory. See Solar Observatory ; Southern Observatory. Officers, Election of xiv List of v Terms of, By-law concerning ix Olive, E. W., Report on grant to (Botany), 1902-03 xxvii Organisms, Lower, Report on grant to H. S. Jennings for experiments on behavior of . . . xliii Paper by H. S. Jennings on behavior of, Publication of 1 Osmotic pressure, Report on grant to H. N. Morse for researches on. . . xxx Oussakovsky, General, Acknowledgment to 273 Overton, James B., Academic training of xlix appointed Research Assistant xlviii 304 CARNEGIE INSTITUTION P Page Paikend, Ruins of, Observations on 279 Palseocastro, Archeological excavations at 240 Paleontology, Applications for grants in li Reports on grants in, 1902-03 xxxvii Palomar mountain, Advantages of, as site for observatory 79, 80 Temperature changes on 79 Vegetation on 78, 79 Water supply on ... . 79 Parallax, stellar. See Stellar parallax. Paschen, F. , Acknowledgment to 170 Pawnee Indians, Ethnologic investigations among, Report on, by G. A. Dorsey xv Peirce, Herbert, Acknowledgment to 272 Pender, Harold, Report on grant to (Physics), 1902-03 xxxix Pergamon, Archeological excavations at 239 Perkins, H. F., Academic training of xlix appointed Research Assistant xlviii Perkins, Janet, Report on grant to (Botany), 1902-03 xxviii Permian reptiles, Morphology of, Report on grant to E. C. Case for work on xxxvii Petrie, Flinders, Work of, in Egypt 217 Philippine flora, Report on grant to Janet Perkins for preliminary studies on xxviii Phillips, C. A. , Acknowledgment to 170 Philology, Applications for grants in li Phonetics, Experimental, Report on grant to E. W. Scripture for re- searches in xl See also Human voice. Photographs, Astronomical, Report on grant to E- C. Pickering for study of xxi Solar, Report on grant to G. E. Hale for measurements of xx Photometric observations, Importance of 43 Physics, Applications for grants in li Grants recommended by Advisory Committee on lii Reports on grants in, 1902-03 xxxviii Research Assistants in xlix Physiology, Applications for grants in li Grants recommended by Advisory Committee on lii Reports on grants in, 1902-03 xxxix Research Assistants in xlix Piazzi's star observations, Report on grant to H. S. Davis for reduction of xix Pickering, E. C, Acknowledgment to 170 Report on grant to (Astronomy), 1902-03 xxi Pine mountain, California, Location and elevation of 100 Pirsson, L. V., cited on need for experimental work in geophysics 179 Pirsson, L,. V., et al., Suggestions by, as to geophysical investigations. 195-201 INDEX 305 Page Planetary observations from southern hemisphere, Desirability of no Plant hybrids, Report on grant to W. A. Cannon for investigation of. . xxvi Plants, Fecundation in, Paper on, by D. M. Mottier, Publication of . . . 1 Plehve, Mr. , Acknowledgment to 272 Plesiosaurs, Report on grant to S. W. Williston for monographing. . . . xxxviii Poincare\ H., cited on effect of ocean tides , 267 cited on establishment of geophysical laboratory 177 Pomeroy, Fred. E-, Carnegie table at Woods Hole laboratory occu- pied by xlv Porto Rico, Archeological explorations in. . xvii Poslovsky, General, Acknowledgment to 273 President, Appointment of, By-law concerning viii Vacancy in office of, By-law providing for filling of x Problems of solar research, General nature of 59-65 Psychology, Applications for grants in li Grants recommended by Advisory Committee on Hi Reports on grants in, 1902-03 xl Research assistants in xlix Publication, Applications for grants in li Publication fund, Appropriation for xiii Publications authorized, List of 1 Pulkowa Observatory, Astronomical observations at 128-130 Pumpelly, Raphael, Report by, on archeological and physico-geo- graphical reconnaissance in Turkestan 271-287 Report on grant to (Exploration), 1902-03 xxxiii Pumpelly, R. W., member of expedition to Turkestan 272 Work of, in trans-Caspian region.. xxxiv, 286 Putnam, Herbert, Report on grant to (Bibliography), 1902-03 xxiv R Radial motions, Value of investigations of 37-39 Radial velocities, Determination of, Importance of 140 Randolph, Epes, Acknowledgment to , 72 Rare earths, Report on grant to L. M. Dennis for investigation of xxx Recent and fossil corals, Report on grant to J. E. Duerden for investi- gation of xli Reed, William M., Report on grant to (Astronomy), 1902-03 xxii Religion, Applications for grants in , li Reptiles, Permian, Report on grant to E. C. Case for continuation of work on morphology of xxxvii Research Assistants, Academic training of ..... xlix Circular defining xlvii List of xlviii Selection of xlviii Researches, Large, Appropriation for xiii Minor, Appropriation for xiii Special, Appropriation for xiii 306 CARNEGIE INSTITUTION Page Reserve fund, Appropriation for xiii Rhodes, Archeological excavations at 240 Ricco, A., Letter from, concerning Solar Observatory 155 Richards, Theo. W., Report on grant to (Chemistry), 1902-03 xxxii Richards, Theo. W., and Stull, W. N., Paper by, on new method for de- termining compressibility, Publication of 1 Richthofen, Baron von, Acknowledgment to 272 Ridler, Mr., Acknowledgment to 272 Rock, Compressibility of, Researches on 266-267 Rocks, Constants of, Need for work on 181 Deformation of, Experimental work on 180-181 Flow of, Report on grant to F. D. Adams for investigation of xxxiv Liquid and solid, Relations of, Suggested investigation of 178-179 Rogers, J. G., Acknowledgment to 17° Root, Elihu, elected Vice-chairman Board of Trustees xiv Rubens, H., Acknowledgment to 17° Ruediger, Gustav, Carnegie table at Woods Hole laboratory occupied by xlvi Russell, H. C, Acknowledgment to 43 Russell, H. N. , Academic training of xlix appointed Research Assistant xlviii s Samarkand, Ruins of, Observations on 279-281 Samikon, Greece, Need for explorations near 228 Samos, Archeological excavations at 240 San Bernardino Forest Reserve, Roads in 97-98 San Bernardino mountains, Trend of 93 San Bernardino peak, Elevation of 93 San Diego region, Fog level in 91 San Gabriel mountains, Dust line in ...... 95 Trend of 93 San Gabriel valley, Sea breeze through 93~94 San Gorgonio mountain, Elevation of 93 San Jacinto mountains, Earthquakes in . 99 San Jacinto peak, Location and elevation of 99 San Miguel peak, Location and elevation of 75 Vegetation on 7° Water supply on 76 Santa Ynez mountain, Location and elevation of 99 Water supply and vegetation on 99-100 Schmidt, Professor, Acknowledgment to 272 Schwarz, Ernest, cited on need for experimental work in geophysics . . 179 Schuster, A., Letter from, concerning International Magnetic Bureau.. 210 Letter from, concerning Solar observatory 147-149 Scott, George W. , Academic training of xlix appointed Research Assistant xlviii INDEX 307 Page Scott, J. W. , Carnegie table at Woods Hole laboratory occupied by xlv Scripture, E. W., Report by, on investigation of mechanics of the human voice 243-249 Report on grant to (Psychology) , 1902-03 xl Seal, Question of, referred to Executive Committee, with power xiv Secretary, Election of xv Financial statement submitted by xi-xii Statement of assets submitted by - xiii Sederholm, J. J., quoted on establishment of geophysical laboratory at Washington 177 Seeliger, H., Letter from, concerning Southern Observatory 118-121 Seismology, Investigations in, Need for cooperation in 183-184 Semenof, Mr., Acknowledgment to 272 Serpents, Poison of, Results of investigations of, by Flexner and Nogucbi, Publication of 1 Seymour, T. D., Report by, on archeological investigations in Greece and Asia Minor 213-242 Siderastrea, Paper on, by J. E. Duerden, Publication of 1 Slichter, C. S., Collaboration with 261 Smith, Grant, Carnegie Table at Woods Hole laboratory occupied by. . xlv Snake venom, Results of investigations of, by Flexner and Noguchi, Publication of 1 Societies, Handbook of Learned, Report on grant to Herbert Putnam for preparing and publishing xxiv-xxvi Solar and Southern observatories. See Southern and Solar. Solar Observatory, Auxiliary station for 18 Atmospheric conditions desired for 52~54 Buildings for, Suggestions concerning 68-69 Correspondence relating to I43_I7 General recommendations concerning establishment of 13-20 Grant recommended by Advisory Committee on lii Great reflector for, Advantages of 18 Plans and estimate of cost for 66-70 Policy of, as proposed 19-20 Principal objects of ... . 50-52 Principal problems to be studied by 59-65 Site for, Considerations governing selection of I5-I8 Report on investigation of, by W. J. Hussey 71-104 Suggestions concerning 147, 153, I55> l5%> ID7 Station A, Plan of work for 68 Site for 66 Stations B and C, Plans for work at 69 Telescopes for, Requirements of 5^-59 Solar photographs, Report on grant to G. E- Hale for measurements of. xx Solar research, Principal problems of, General nature of 59-^5 Solar system, Analytical review of literature on 262 South America, Observatory sites in 1 n South Africa, Observatory sites in 44, 111, 123, 126 308 CARNEGIE INSTITUTION Page Southern hemisphere, Astronomical observing station in, Need for establishment of 9, 24-28 Southern Observatory, Buildings for, Suggestions concerning 46-47 Confidential statement in regard to, Extracts from 106-107 Correspondence relating to 106-143 Establishment of, as an expedition 4&-49 Desirability of 1 18-1 19 General recommendations concerning project for 9-i3 Grant recommended by Advisory Committee on Hi Instrumental requirements of 28-43 Plan of work for 111-112 Site for, Conditions determining selection of 15-18. 43~46 Suggestions concerning ill, 116, 120, 122-123, 126, 136, 141 Staff and organization of, Suggestions concerning 47-4-8 Work proposed for, Suggestions concerning 28-43, 108-143 Southern and solar observatories, Drawbacks to establishment of 8 General recommendations concerning 6-20 Relations of, to existing institutions 8-9 Report of committee on investigation of projects for 5~I7° Report on grant for investigation of projects for xix Sparta, Archeological explorations near, Desirability of 228, 229 Spaulding, H. G. , Carnegie table at Woods Hole laboratory occupied by. . xlv Speech, Melody of, Investigation of 253-254 Rhythm of, Investigation of 254-255 See also Human voice. Sponges, Deep-sea, Report on grant to H. V. Wilson for investigation of. xliv-xlv Staats, W. R., Acknowledgment to 17° Stars, Double. See Double stars. Stars, Variable, Report on grant to Wm. M. Reed for observations on xxii Stellar parallax, Determinations of, Importance of 118, 119, 121, 136, 137 Instruments for I37~I39 Measurements of, Desirability of 36-37 Methods of 35 Value of 34 Report on grant to G. E. Hale for measurement of xx Sterrett, Professor, Archeological work of, in Asia Minor 220-221 Stewart, George W. , Acknowledgment to 170 Stieglitz, Julius, Collaboration with 261 Stoue, E. J., Work of, on Cape Catalogue 109 Stratton, S. W., Acknowledgment to 170 Strawberry valley, Location and elevation of 99 Vegetation and water supply on 99 Strong, R. M., Academic training of .... xlix appointed Research Assistant xlviii Carnegie table at Woods Hole laboratory occupied by xlv Stubendorf, General, Acknowledgment to 272 Student research work in Washington, Report of committee on, placed on file xlvi INDEX 309 Page Stull, W. N., and Richards, T. W., Paper by, on new method for de- termining compressibility, Publication of 1 Suess, E., cited on need for experimental work in geophysics 179 Opinion of, as to establishment of geophysical laboratory at Wash- ington 177 Sun, Constitution of, Necessity for investigation of 59_6i Heat radiation of, Necessity for observations on 62-64 Sun spots, Importance of study of 160-163 Supra-renal gland, Report on grant to John J. Abel for chemical inves- tigation of. . . . xxviii Sydney, New South Wales, suggested as site for Southern Observatory. 44 Syria, Archeological exploration in, Present condition of 219 T Taquitz peak, California, Elevation of 99 Taquitz valley, Elevation of 99 Tasmania, Site for Southern Observatory in, Advantages of 45 Teall, J. J. H., quoted on establishment of geophysical laboratory at Washington 1 76 Tegea, Archeological excavations at 239 Telescopes, Reflecting, New types of 54~57 Use of, in conjunction with laboratory instruments .... 54-59 Temperature, Distribution of, in the earth, Study of 262-265 Tennessee, Archeological field work in xvi Thebes, Archeological explorations near, Desirability of 22, 229 Thome, John M., Acknowledgment to 44 Thomson, Elihu, Acknowledgment to 170 Timberlake, H. G., Academic training of xlix appointed Research Assistant xlviii Death of xlviii Tingle, J. B., Report on grant to (Chemistry), 1902-03 xxxii Tittmann, O. H., Letter from, concerning establishment of Interna- tional Magnetic Bureau 206-207 Tornebohm, A. E., quoted on establishment of geophysical laboratory at Washington 177 Townsend, Miss A. B., Carnegie table at Woods Hole laboratory occu- pied by xlv Trans-Caspian region, Itinerary of Professor Pumpelly in 272-274 Report of Prof. R. Pumpelly on preliminary examination of 271 Report on grant to Raphael Pumpelly for preliminary examination of xxxiii Trustees, Annual meeting of, By-law concerning viii Election of xiv List of iv Minutes of third meeting of [abstract] x-xiv Officers of, Election of xiv 3*0 CARNEGIE INSTITUTION Page Turkestan, Ancient towns of 278-281 Archeological and physico-geographical reconnaissance in, Report on, by Raphael Pumpelly 271-287 Evidences of former occupation of 276 Glacial epochs in 285-287 Outline sketch of 274-276 Physical geography of 274-276 Recommendations for work in 284 Tumuli in 277-278 See also Trans-Caspian region. Turkey, Archeological work in, Present condition of 218-219 Law of, as to exports of antiquities 234-235 Turner, H. H., Acknowledgment to 170 Letter from, concerning project for Southern Observatory 108-112 IT Ulianin, General, Acknowledgment to 273 V Van Hise, C. R., Report by, on Geophysics 173-184 Report on grant to (Geophysics), 1902-03 xxxv Van't Hoff, J. H., cited on establishment of geophysical laboratory. . . 177 Work by, on cr)'stallization of salt and gypsum 179-180 Van Tyne, Claude H., Work of , on historical archives of Washington. xxxvi Variations of latitude, Importance of work on 41-42 Vogel, H. C, Letter from, concerning Solar Observatory 149 Vogt, , cited on need for experimental work in geophysics 179 Voice, Human. See Human voice. Volkovnik, Colonel, Acknowledgment to 273 Vowels, Nature of 248-253 w Walcott, Charles D., elected Secretary of Board of Trustees xiv Waldo, Leonard, Report on grant to (Engineering), 1902-03 xxxiii Ward, William Hayes, Report on grant to (Archeology), 1902-03 xvii Washington, H. S., cited on need for experimental work in geophysics. 179 Washington, H. S., et al., Suggestions by, as to geophysical investiga- tions 195-201 Washington, Establishment of geophysical laboratory at, Opinions of geologists on importance of 176-178 Historical archives of, Report on grant to Worthington C. Ford for examination of xxxvi Student research work in, Report of committee on, placed on file. xlvi Water lilies, Monograph on, by H. S. Conard, Publication of 1 Report on grant to H. S. Conard for study of types of xxvi Weights, Atomic, Report on grant to T. W. Richards for investigations of values of xxxii INDEX 311 Page Whitehead, J. B. , Jr. , Academic training of xlix appointed Research Assistant xlviii Whitman, C. L., Report by, on work at Woods Hole laboratory xlvi Whitney, Mary W., Report on grant to (Astronomy), 1902-03 xxiii Wieland, G. R., Report on grant to (Paleontology), 1902-03 . . . xxxvii Wilczynski, E. J., Academic training of xlix appointed Research Assistant xlviii Wilder, F. A., Gypsnm deposit studied by 269 Willis, Bailey, Report on grant to (Geology), 1902-03 xxxv Williston, S. W., Report on grant to (Paleontology), 1902-03 xxxviii Wilson, E. B., Report on grant to (Zoology), 1902-03 xliv Carnegie table at Naples Biological Station occupied by xlvi Wilson, H. V., Report on grant to (Zoology), 1902-03 xliv-xlv Wilson, W. E., Letter from, concerning Solar Observatory 151-152 Wilson, Mount. See Mount Wilson. Wolff, John E., cited on need for experimental work in geophysics 179 Wolff, John E., et al., Suggestions by, as to geophysical investigations. 195-201 Wood, R. W., Report on grant to (Physics), 1902-03 xxxix Woods Hole. See Marine Biological Laboratory at. Wright, Carroll D., re-elected member of Executive Committee xiv Wrinch, F. S. , Academic training of xlix appointed Research Assistant xlviii Wiirzburg, Physical laboratory at, Visit of Dr. Becker to 186 Y Yanchevetzki, Mr. , Acknowledgment to 273 Yermolof , Mr. , Acknowledgment to 272 Young, C A., Letter from, concerning Solar Observatory 143-144 z Zaitza, Colonel, Acknowledgment to 273 Zoology, Applications for grants in li Reports on grants in, 1902-03 xli-xlvi Research Assistants in xlix ?rv5w T>T. r& i**v *-il-*l -Jt.'r-?~i~H