peaks, the upper sides both tinted with rosy and violet light while the lower sides were brilliant white. I do not doubt that the toothed form I assign to these peaks is real, which as it contrasted with that of the first appendages I have described, I verified with great care; moreover, in shifting the telescope, whose high power permitted a sight of only a small part of the solar disc at one time, I saw a third peak a little higher, also tooth-formed, and resembling the two others in color and form, differing only in its larger dimensions. The remainder of the disc offered nothing remarkable, and on returning to the upper region I found the two first described clouds unchanged. As the moment of reappearance of the Sun approached, and while waiting for the first rays, I made, during about 20s, perhaps my most important observation. The margin of the disc which two minutes before was entirely white was now tinged by a delicate fillet of unappreciable thickness of a purplish red-then as the seconds glided by, this fillet enlarged by degrees and formed soon around the black disc of the moon, over a breadth of about 30° a red border perfectly defined in thickness, crescent-formed and with an irregular outline above. At the same instant the brilliancy of the part of the corona which during the last second emerged from behind the moon's disc was exalted so rapidly that I was in doubt if the sun's light was not returned. It was only on the reappearance of the direct rays, the brightness of which obliterated in turn the corona, that I was sure of the nature of three phenomena present at the same time, which I thus sum up.

1. The visible part of the emergent Sun over its whole breadth and up to the height of seven or eight seconds was covered by a bed of rosy clouds, which appeared to gain in thickness as they emerged from behind the disc of the moon. Must we believe that the entire surface of the sun is overspread at a small elevation as it is strewn with faculæ, and that the roseate clouds are emanations, appearing like spots on the sun's disc?

2. The intensity of the light in the corona which is always white, varies with great rapidity in the immediate vicinity of the Sun's disc. 3. The reappearance of the direct sunlight was at 3h 0m 498.0. Total obscuration continued 3m 148.3. The disc of the moon completely cleared the Sun at 4h 6m 208."

[M. Foucault's interesting observations on the photographs, etc., are unavoidably postponed for want of room.]

LeVerrier goes on to state that the observation of his party authorize, in his opinion, important modifications in the generally received notions respecting the physical constitution of the Sun. Arago in his notice of solar eclipses says, "where exist the reddish flames with well defined outlines which during the total eclipse of the 8th of July, 1842, passed considerably beyond the outlines of the lunar disc? These flames were either in the Moon, or in the Sun, or in our atmosphere; unless, indeed, denying their actual existence, we regard them as an effect of light, for example as phenomena of diffraction."

The two last suppositions have found few partisans. Before adopting any hypothesis it is necessary to decide by observation a certain feature of the phenomenon. During the eclipse, the disc of the moon moves across the disc of the Sun. But do these reddish clouds follow the moon in

its movement? or does each cloud remain invariably above the same point on the solar disc? In the first case the origin of the luminous clouds is to be sought in the Moon; in the second case, these clouds belong to the Sun. For clearness sake, assume the latter supposition, and observe what appearances should present themselves when the lunar disc passes like a screen over the whole. Consider first a cloud situated on the east and adherent to the Sun's limb. This object will be visible at the instant when totality commences. The advancing moon will regularly, at the rate of a half second of arc in a second of time, cover with its limb successively the lower then the middle and lastly the higher portions thus constantly diminishing the height of the cloud. For a cloud situated on the west, these appearances will be reversed, its magnitude increasing as the moon gradually uncovers it. If then the roseate appendages seen during a total eclipse, depend on the sun, the fact should appear by the variation in height between those which appear in the east and the west. The phenomena will appear otherwise if the clouds appertain to the moon.

In the absence of equatorial solar clouds, the question in dispute can still be decided by observations on those seen on the south or north of the disc. The height of these clouds ought not to vary, it is true, whether they belong to the moon, or to the sun, but in the latter case, carried away by the sun they would be displaced on the lunar disc with a certain velocity, while if they are adherent to the moon's disc, they would not be so displaced Hence the study of the height of the luminous clouds, whether east and west or north and south, has the highest interest. All the elements of the desired demonstration are found in the Spanish observations. In my first report, I mentioned the successive increase in thickness of a band of rosy clouds visible from the east to the end of the eclipse. Messrs. Yvon Villarceau and Chacornac have carefully noted the motions of a cloud, situated on the north. This cloud, according to M. Villarceau, in two minutes' time was displaced 34° on the moon's disc, in moving to the west. The measurements of M. Chacornac cover an interval of over six minutes in time, in which the cloud moved 111°.

Beautiful observation, and one which could not have been hoped for! We see that the duration of the motion studied by Chacornac, much exceeds the time of total obscuration. The last measure was made more than three minutes after sun-light had reappeared! It is important to note, among other points that this was not done with a cloud vaguely seen after the return of sunlight, but fortunately it was a measurement so carefully made as to be a guaranty against the possibility of illusion. It should be added that the displacement of the luminous cloud determined by the observations made at the Sanctuaire, is precisely equal to that required by calculation, assuming the cloud to belong to the Sun. There remains, then, no foundation for a doubt, as to the nature of the rosy clouds which have been variously called flames, mountains, protuberances, and clouds.

The observation on one of the appendages, perfectly isolated from the disc of both the Sun and Moon and of a sharply pronounced character, and on the other the appearance of a rosy band on the west at the inoment of emersion, and the rate of motion of a second appendage, fixed by Villarceau and Chacornac, prove that these objects belong to the Sun.

Let us then hereafter give the name of solar clouds to the rosy appendages which become visible when the solar light is sufficiently dimmed.

A few words more will finish the description of the phenomenon and of the observations. Ismail-Effendi, a young Egyptian attached to the Paris Observatory for three years past, a very expert astronomer, and who accompanied the French expedition to Spain, has sent me a drawing which proves the appearance of luminous clouds in the east immediately before the commencement of the eclipse. The clouds in question form a slightly elevated but continuous band embracing 90° of the outline of the Sun. This band was not long visible, but was eclipsed behind the lunar disc, and it had in effect ceased when I passed over this region in exploring the whole periphery with a power which allowed me to see only portions successively.

The magnetic observations were made at Paris, the variations being sensibly simultaneous for the whole of Europe, and M. Desains, who took note of the magnetic observations, detected no perturbations during the eclipse.

Physical constitution of the Sun.-A reconstruction or even a complete abandonment of the theory hitherto prevalent as to the physical constitution of the Sun appears to me essential. It must give place to one far more simple.

We have been hitherto assured that the Sun was composed of a central dark globe; that above this globe existed an immense atmosphere of sombre clouds, still higher was placed the photosphere, a self-luminous, gaseous envelope, and the source of the light and heat of the sun. Where the clouds of the photosphere are rent, says the old theory, the dark body of the Sun is seen in the spots which so frequently appear. To this complex constitution must be added a third envelope formed of the accumulation of roseate clouds.

Now, I fear that the greater part of these envelopes are only fictionsthat the Sun is a body, luminous, simply because of its high temperature, and covered by an unbroken layer of roseate matter whose existence is now proved. This luminary thus formed of a central nucleus, liquid or solid, and covered by an atmosphere, falls within the law common to the constitution of celestial bodies.

[M. LeVerrier goes on to discuss with some detail the solar spots in the light of these new views, but this we must defer for another occasion. It is certain that a subject of so much interest will command much consideration from physicists and astronomers and we shall take care to give it the attention it deserves.

Nor will the question be settled peaceably already M. Faye (Comptes Rend., Aug. 13) in presenting to the French Academy a long letter from Baron Feilitzsch with an account of his observations (also in Spain), declares it to be his opinion as well as that of Baron F. that the eclipse of 1860 furnishes the most decisive evidence in favor of the opinion which refers the corona and the luminous clouds to simple optical appearances, and not to the essential constitution of the Sun or of his atmosphere. M. Faye adds that the opinion appears to be confirmed by a comparison of the results of other observers that the Sun has no atmosphere and that the appearances recorded are purely optical!-EDs.]

THE

AMERICAN

JOURNAL OF SCIENCE AND ARTS.

[SECOND SERIES.]

ART. XXVIII.-Lecture on the Gulf Stream, Prepared at the Request of the American Association for the Advancement of Science; by A. D. BACHE, Supt. U. S. Coast Survey.*

[Delivered before the American Association for the Advancement of Science, at Newport.]

By request of the Association, at their last meeting, at Springfield, I now present a summary of the results of the Gulf Stream explorations made by the officers of the Coast Survey.

The Gulf Stream is the great hydrographic feature of the United States coast, and no survey of the coast could be complete for purposes of navigation, without it. Hence the explorations have been early undertaken and thoroughly carried on. But as it required peculiar means and special adaptation in the officers to this line of research, and did not require a continuous survey, the work has been executed from time to time, as means and officers could be had without interference with the more regular operations of the hydrography.

An act of Congress which refers to this Survey, requires the immediate presentation of its results to Congress and they have therefore been discussed as soon as procured and have been given to the public.

This is the great sea mark of the coast of the United States, both Gulf and Atlantic, and its qualities as hindrances and aids to navigation require that the navigator should be well informed in regard to it.

* Communicated by the Author.

AM. JOUR. SCI.—SECOND SERIES, VOL. XXXI, No. 90.—NOV., 1860.

In order to present an intelligible summary of the results obtained by the Coast Survey in the short time allowed for a lecture, it is necessary to condense the subject very considerably, to omit matters at all extraneous to the subjects in hand, and to Confine myself to a brief and direct statement of the means eṁployed in examining the stream from its surface to its depths, the method of studying the results, and of the results themselves.

The temperatures in and near the Gulf Stream, are among its most striking peculiarities, and therefore have formed one principal object of observation. It will be necessary in order to bring the subject within limits, to confine myself chiefly at this time to the consideration of this class of facts and to the results and laws connected with them.

I shall proceed therefore to consider the subject under the following heads:

1. The Instruments for determining depths and temperatures and for obtaining specimens of the bottom.

2. The plan of research.

3. The method of discussion of the results.

4. The results, consisting of type-curves of the law of change of temperature with depth, at several characteristic positions. Type-curves showing the distribution of temperatures across the stream, represented by two sets of curves, one in which the vari able temperatures at the same depth is shown, and the other in which the variable depth of the same temperature is represented. Upon the diagrams showing these latter curves, the figure of the bottom of the sea is given, where it has been obtained.

Discussion in regard to the cold wall, which is one of the most interesting features of the approach to the Gulf Stream, 5. The limit of accuracy of the results.

6. The figure of the bottom of the ocean below the Gulf Stream.

7. The general features of the Gulf Stream as to temperature. These points are illustrated by diagrams, enabling the eye to follow the results as they are stated.

I. INSTRUMENTS.

1. For Temperatures.--The instrument for determining temperatures should fulfill the two conditions of registering its indications and of being unaffected by pressure. The common mercurial thermometer, while it answers perfectly for the determination of temperatures at the surface, fails in both the conditions stated. The ordinary self-registering thermometer, or self-registering metallic thermometer, in the watch form, as made by Breguet, Montandon, and Jürgensen, when provided with a suitable cover to protect it from pressure, answers a good purpose, and has been extensively applied in the course of the observations. As