APPENDIX.

Letter to the Editors from Dr. B. A. GOULD, Director of the Cordoba Observatory, dated Cordoba, April 26, 1871.

WHEN I wrote you, at the beginning of November, I felt small doubt that our Observatory would be in working order so far as mason work and carpentry were concerned, before the commencement of the New Year. The brickwork was completed at the close of November as I had anticipated; but even now as I write, the portion of the building which was first provided is not finished, although a very few days will enable me in all probability to begin the mounting of the instruments. So far as delays and interruptions of every sort are concerned, the enterprise has met with a very exceptional amount of obstacles, and only three days ago my instruments arrived from Germany after ten months of delay from war, ice, storms and quarantine.

The meridian circle and photometer are now securely housed, and, so far as I can yet judge, have suffered no essential injury. Our little library too has arrived, and I need not say with what earnestness we are looking forward to a sight of the catalogues and books of reference, now hidden within the iron-bound boxes. Should no unexpected obstacles arise, we shall be able to put up some bookcases, and unpack the boxes within the coming week.

It is now seven months since our astronomical party arrived in Cordoba, and during this long period we have been without instruments, and nearly destitute of books, notwithstanding the many precautions taken to avoid such a contingency. Fortunately I had brought with my personal effects the catalogues of Lacaille, Brisbane, Taylor and Ellery; and the catalogues published by the British Association were sent me from England. Thanks to these, I am indulging the hope that these seven months will not prove to have been spent in vain.

As intimated in my former letter, I resolved, as soon as the delays became manifest, to turn our attention to the formation of a Uranometry of the Southern sky-in other words, to the preparation of a catalogue of all stars between the South Pole, and 10° of N. Declination, which are here visible to the naked eye, assigning to each star its estimated magnitude. This work has been now actively going on for six months, and with a degree of success which I had scarcely ventured to anticipate. The sky of Cordoba, although very far indeed from rejoicing in that eternal spring and unclouded blue which I had been led to expect, possesses when clear a wonderful transparency, and exhibits to the sharp eyes of my assistants an almost incredible number of faint stars, probably at least twice as many as can be seen in the most favorable nights at home. The lowest limit of visibility to the unaided eye, I have not yet undertaken to determine; but we see fully one-third of all the stars recorded by Lacaille as of the 7th magnitude, and we have a dozen or more of cases where Lalande has noted the star as 8th.

Our scale of magnitudes is based upon that of Argelander in his Uranometria Nova, and to secure as complete an accordance as possible our comparisons are made with stars observed by him within the zone comprised between 5° and 15° of N. Declination, since this zone has the same meridian altitude at Cordoba and at Bonn, and the light of the included stars is thus similarly affected by atmospheric absorption.

The establishment of standards of magnitude within this belt has been by no means the least laborious and troublesome portion of the undertaking; since no star is accepted as a standard to which the same magnitude has not been assigned by the independent estimates of four observers. The large number of stars within this type-belt, which could not be seen by Argelander in Bonn, affords an excellent measure of the transparency of the sky of Cordoba.

For constellations farther South the comparison is of course not so fair, on account of their superior altitude here, still you may form some idea of the work in hand when I tell you that in Orion we have twice the number of stars given by Argelander, and that in Canis Major, the whole of which is visible at Bonn, though to be sure its Southern boundary has only an altitude of a little more than 64°, we have 200 stars, while Argelander saw but 39.

A good deal more than half the work is now done; perhaps two-thirds of the hemisphere have been pretty well scrutinized, and the work of reducing the stars places to the mean equinox adopted is very well advanced. The total number of stars recorded thus far is about 4100, exclusive of those observed in the type-belt.

The delays of our instruments and of the Observatory building, though in themselves vexatious, have thus been compensated by the opportunity of preparing the Uranometry which ought to be essentially completed by the first of October, unless this should in its turn be too much delayed by the new work soon to be undertaken, in conformity with my original plan. An essential feature of my present scheme for the Uranometry consists in careful measurements of the magnitudes of stars above the 4th magnitude, and for these, of course, the greater part of a year must elapse after the photometer shall have been put in order by repairing the small damages which it has suffered on the voyage.

Our observations have greatly impressed me with the thoroughness and excellence with which Lacaille accomplished his work at the Cape of Good Hope with the poor means at his disposal nearly a century and a quarter ago. This devoted astronomer, having only a telescope half an inch in aperture and magnifying 8 times, observed, within a period of 11 months from the commencement of the se.ies, something more than 100 zones, covering the region South of the Tropic of Capricorn. Like those of sundry other astronomers, most of his observations remained unreduced for the greater part of a century; but the catalogue computed from these observations at the expense of the British Association for the advancement of Science, and published by that body in 1847, contains the places of nearly 10,000 stars, which experience shows to have been determined with a degree of precision decidedly greater than he himself had supposed. And although his zones overlapped but little at their margins, so that only a small proportion of the sky was observed more than once, the scrutiny must have been extremely thorough for such stars as his little telescope would make inanifest. The number of stars south of the Tropic, which we have detected, and which are not in his catalogue, is relatively quite insignificant, so that the task of identification has been by far less difficult than I was prepared to expect.

The recent publication, by Admiral Sands of the Washington Observatory, of Gilliss's Southern Catalogue of about 2000 stars affords a valuable supplement to Lacaille, since it gives observations of many stars for which there seemed reason to suspect errors in Lacaille's determination. And if, as recent letters from home give reason to hope, this is to be followed by Gilliss's splendid series of zone observations, comprising some 23,000 stars within 24 of the South Pole, observed in Chile twenty years ago, the Southern observer will receive a truly effective assistance in his labors. Indeed, after so long a period of apparent inaction, a new day seems dawning for stellar astronomy in the Southern Hemisphere. The careful and abundant observations of Maclear at the Cape of Good Hope, which have been accumulating for a quarter-century are now to be reduced and catalogued by his energetic successor Mr. Stone; and from the shores of Australia we are already receiving, thanks to the industry and ability of Mr. Ellery, an annual instalment of meridian observations, which may fairly challenge comparison with the most exact which are furnished by the first observatories of the Northern Hemisphere.

The difficult question of the Southern Constellations is of course now forcing itself in an especial manner upon my attention, in connection with the Uranometry. What constellations to retain, and what to disregard among the various suggestions of various astronomers, has been a less difficult question than the assignment of boundaries or the adoption of a definite and consistent notation from out the chaos which rules in sundry portions of the Southern sky. These matters, comparatively insignificant in many relations, acquire a supreme importance when questions of nomenclature become prominent, as in the work now in hand. Bayer, whose authority is accepted as law for the notation of Northern stars, named many of the Southern stars simply from descriptions given him by Southern navigators. Lacaille was either unaware of Bayer's notation or gave no heed to it, and later astronomers have increased rather than diminished the confusion. The difficulties were ably pointed out by the younger Herschel, but such few remedies as he suggested have tended rather to aggravate the evil, as for instance, in the case of Argo Navis, where the practical and effective suggestion, adopted by Baily, in the three catalogues of the British Association, of dividing this huge and unwieldy constellation into four smaller ones corresponding to the parts of the Ship, as indicated by Lacaille, is more than counterbalanced by the other recommendation, likewise adopted by Baily, that so far as the Greek alphabet is used, the original constellation be retained, while each of the four sub-constellations has its own special nomenclature in the two series of letters of the Latin alphabet. Nor are the three catalogues edited by Baily for the British Association altogether accordant as regards either the constellation-boundaries, or the notation of the stars, notwithstanding his efforts to furnish some relief for the existing confusion. The same Greek letter occurs twice in the same constellation in more than one instance in these catalogues, while other letters are entirely wanting.

η

Let me give you an illustration of the confusion encountered in a study of prominent Southern stars. Take the constellation Telescopium, one which has every reasonable claim to be accepted and retained. Here B is in fact 7 Sagittarii, y, n, and o are in Scorpius, and σ is in Corona Australis. Or take Piscis Austrinus and follow the catalogues. Here Brisbane's e is Baily's y; Brisbane's is Taylor's o and Baily's ; Brisbane's y is Baily's e, while Taylor gives it no letter. Brisbane has two ks, one being Bayer's 7, while Baily assigns no letter to the other; but Bayer's x is y Gruis of Lacaille (and Baily). Brisbane's is Baily's (and Bayer's); of Brisbane's two ds one is Baily's 7, and the other has no letter in his catalogues; Brisbane's vis Taylor's w, while Baily gives no letter to it; Taylor's y, and have no letters given to them by either Brisbane or Baily. Indeed Baily puts in Aquarius.

Now the application of any general rule seems out of the question. For such stars as are visible in Central Europe, Bayer's notation should assuredly be retained, yet for many stars farther South, the star actually cannot be identified with certainty to which his letters were intended to apply. Where Bayer's notation fails, Lacaille's has the next claim; yet in many instances he has employed a letter already assigned by Bayer in a more Northern portion of the same constellation. Not unfrequently too Baily has attempted to improve upon both Bayer and Lacaille, and not with the best success; yet inasmuch as every existing Southern Observatory, so far as I am aware, has been organized by some astronomer whose native tongue was English, and who has therefore depended to a greater or less extent upon the three catalogues of the British Association, this "improved" notation, like the "improved" notation of Bessel's star-constants, a, b, c, d, has found a wide adoption.

Add to this that, so far as I am aware, no attempt has been made to give precise boundaries to the several constellations, and you will see that the task of arrangement is no slight matter, when every visible star is to be assigned to some definite constellation. This implies the establishment of boundaries,

and one needs but to glance at any celestial globe or atlas to convince himself that this is a process more easily spoken of than accomplished. If performed in a manner acceptable to astronomers it will find prompt adoption, and evoke order from confusion; if, however, it should fail of approval, it will but add one more chaotic influence. Any attempt at such a revision and establishment of boundaries should be restricted by certain fixed regulations, prescribed in advance, and not to be transgressed upon any pretext; if such can be judiciously laid down, and yet found upon trial not to be incompatible with an arrangement of boundaries easy of recognition and of description, I see no reason to doubt their glad reception by astronomers, as a simple means for substituting for the existing confusion a well ordered and unmistakeable system.

Notwithstanding some misgivings, I am at present occupied in the attempt to arrange the Southern constellations in such a way that the changes may be regarded by astronomers as only for the better.

During the last week we have unpacked the equatorial, and have mounted its bed-plate upon a pier of white marble, from the Sierra four leagues away. The instruments appear to have arrived in perfect condition, and as soon as the dome is made rain-tight, and the interior of the building plastered, I shall proceed to the mounting of the telescope, for which all needful preparations are already made. That the shutters should be rain-tight, is a much more essential condition than I had been led to suppose, for the summer rains here are sudden and vehement. The theory of an eternal summer is thoroughly disposed of; for during the last three months we have not had a dozen perfectly clear nights, the sky being overclouded with almost perpetual nimbus, although very little rain has fallen This, I am informed, is the ordinary character of the weather during a considerable part of March and April, the autumn being ushered by a long cloudy season. I wrote you before that I had known no rain here without abundant thunder and lightning. During this long cloudy season a light misty rain has several times occurred without electrical manifestations, although as regards regular showers or copious "rains, I have seen no reason to change my earlier impression. The rainless season is now said to be close at hand. It will assuredly find with us a cordial wel

come.

It

It is to be expected that in the course of our work we may encounter a number of variable stars sufficient to make the number in the Southern Hemisphere approximately equal to that of those already known north of the Equator. As yet however we have not followed through any very decided changes, although there is a considerable number of stars whose magnitudes, as observed by us, differ widely from those recorded by other astronomers, and which also appear to have varied during the period of our observation. The star 7 Argus, has naturally attracted a good deal of my attention. is at present not far from the 6 magnitude and recognizable with great difficulty by the naked eye. In the field of my small Tolles telescope of 5 in. aperture, and 35 in. focal length, it is a conspicuous object, and prominent by its ruddy color among the cluster of which it forms a part, against the bright nebula as a background. With this telescope, the same one which I employed for observing the total eclipse of 1860, I have been examining the whole group; and have found to my astonishment that it exhibits with distinctness a considerable number of stars, which are recorded in Sir J. Herschel's catalogue of this cluster, as being of the 14th magnitude.-(To be continued.)

Party of Geological Exploration under Prof. O. C. MARSH.-Prof. Marsh, with a party of twelve, is about leaving for the Rocky Mountain region and the Pacific coast, to continue his investigations with reference to the Cretaceous and Tertiary vertebrates of the region. He will be absent about six months.

THE

AMERICAN

JOURNAL OF SCIENCE AND ARTS.

[THIRD SERIES.]

ART. XI.-Historical Notes on the Systems of Weather Telegraphy, and especially their Development in the United States; by CLEVELAND ABBE, A.M.

THE recent establishment in our own country of a national System of Weather Reports and the general interest in this enterprise, has induced me to accede to the request of the Editor of this Journal, and to offer the following notes relating to the development of the idea of storm warnings.

It was evidently possible to study with advantage, the progress of atmospheric changes only when the telegraph lines had become widely extended over the earth's surface. It was through the public press-the daily newspaper-that it first became possible to watch the hourly progress of storms, under one's own eye, and to confirm the general laws independently deduced from the closet studies of the professional meteorologist. The first mention that I find of the systematic daily use of these daily press reports, is given by Kämtz, in his "Repertorium," wherein it appears that already in 1835, he began to collate the weather reports published in the Vossische Zeitung of Berlin. In the subsequent history of Weather Telegraphy in Europe, I first find a suggestion by John Bell, made in 1848, at the Swansea meeting of the British Association for the Advancement of Science, that in London it was already possible to receive weather reports with only a few hours' delay, from most parts of Great Britain and Europe, and that this information ought to be utilized for the study and prediction of storms. The general press reports seem to have continued to be in

AM. JOUR. SCI.-THIRD SERIES, VOL. II, No. 8.-AUGUST, 1871.