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The preliminery results of the observations of these new variables are given in the following notes:

(1922) Minimum early in March, about 15 magnitude.

(4696) Not visible in the 12-inch June 20, limit about 13 magnitude. Between 13 and 14 magnitude July 5, with 40 inch.

(6458) Not visible in 12 inch in March, limit 14 magnitude, had risen to 10 magnitude by June 23.

(7258) Minimum in May, about 14.5 magnitude.

(7579) Had passed below the limit of the 40-inch in June, and therefore not brighter than 17 magnitude.

(8517) Stationary at about 15 magnitude in January, rising in February.

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Search Ephemer is for Comet 1884 II, (Barnard).-This comet was not found at its return to perihelion in 1894 and 1895 because of its unfavorable situation. This year again its position is quite unfavorable. It will be at perihelion, according to the ephemerides on October 28, 1900, and will then be only from three to four hours east of the Sun, and about thirteen degrees farther to the south than that body. In the southern hemisphere the situation is somewhat

more favorable and it may be possible that the comet may be found. In the Astronomische Nachrichten No. 3660, Dr. Berberich gives a search ephemeris of the comet, a portion of which we give here.

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As the time of perihelion is uncertain by two or three weeks the observer will need to extend his search to a considerable distance on each side of the predicted place of the comet, possibly as far as a half hour in R. A. and a degree or more in Dec.

GENERAL NOTES.

We have greatly tried the patience of our subscribers for the last three issues, sometimes for good and sufficient reasons, and sometimes for reasons, though beyond our control at the time, were not good reasons. We believe that we will have no more trouble of this kind, and that hereafter each number will be mailed on time.

We have given considerable space in this number to useful tables for the observations of the planet Eros, because there are so many observers who are supplied with telescopes who may wish to do some work of this kind during the weeks to come, that such aid may be quite widely useful.

Observations of the Partial Eclipse of the Sun, May 28, 1900, at Orono, Maine.

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The Recent Solar Eclipse.-The report of the expeditions organized by the British Astronomical Association to observe the total solar eclipse of May 28, 1900, will be contained in a volume shortly to be issued from the office of Knowledge. The work will be edited by Mr. E. Walter Maunder, F. R. A. S., and will contain many fine photographs of the various stages of the eclipse.

Observation of Contacts by the Creighton University Party at Washington, Ga.—The internal contacts were observed with the naked eye. The external contacts were observed by projecting the Sun's image upon a white screen secured by two light wooden rods beyond the eye-piece of a 3-inch telescope. I prefer this way of observing the Sun to the more usual direct-vision method by means of a sunshade or helioscope, because the projection method does away with the heat and glare of the Sun, admits of the use of both eyes and of any desirable magnifying power, is equal, if not superior, in accuracy of observation, and especially because it enables the observer to mark the point of first contact upon the screen and thus obtain the advantages of a position micrometer from a telescope of the most ordinary construction and mounting. The comparison of observed and computed time is as foliows:

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The correction and rate of the chronometer were obtained from the Naval Observatory noon signals at the railroad depot.

The geographical coördinates of my position were, latitude 33° 44′ 13′′ N., longitude 5h 30m 58.9 W. WM. F. RIGGE, S. J.

CREIGHTON UNIVERSITY OBSERVATORY.

Comet b, 1900.-The independent discovery of this comet by Borrelly and myself was made on the same morning, July 23, and at nearly the same date of local time, the instant of my discovery preceding Borrelly's by a few minutes. Although the difference in longitude between the two stations favors my esteemed fellow-worker by about five hours, it is an interesting fact, that the Harvard cablegram announcing my discovery of the comet, reached Kiel two hours before Borrelly's announcement was received. The comet has been an exceedingly fine telescopic object in the 10-inch refractor. For some time after discovery it bordered closely on naked eye visibility. The nucleus and coma were easily visible with the telescope in the presence of a full Moon. Although it is now rapidly fading, the comet will from its favorable position in the northern heavens, remain visible in large apertures for some time to come. Soon after discovery two faint branches or auxillary tails were detected, one upon each side of the main tail. Although the principal tail has become much fainter, as the comet receded from the Sun, it has very singularly maintained its original length of about one degree.

In the first note on page 396 of September number Dr. Wilson inadvertently places my Observatory at Rochester. It is where it has been for thirteen years past, at Geneva, N. Y. On the other hand, the name of their Observatory is Smith Observatory, and not the peculiar name given to it by the compositor at the foot of my note on page 400.

SMITH OBSERVATORY, Geneva, N. Y.
Sept. 10, 1900.

WILLIAM R. BROOKS.

New Form of Telescope.-Referring to telescope decribed in Popular Astronomy. No. 77 page 379, allow me to say that the principle of such a telescope is by no means new. About the year 1872-3 I sent to the English Mechanic drawings of a somewhat similar instrument with concave-convex lens, and in 1870-1 I made a 5-inch aperture telescope on that principle a plano-convex lens having its aberrations corrected by a smaller concave lens and mounted as a Newtonian Telescópe for a gentleman then going to India, uncle to Stanley E. Lane Poole, Esq., now I believe of the British Museum Library, who informed me that it was a success, but I heard nothing from the owner and concluded that he did not consider it worth pursuing. In any instrument of considerable aperture there certainly must be trouble and not a little of it with the oblique rays: and this very important point seems to have been entirely overlooked by the ingenious projectors. Nor is this at all an unusual phenomenon. Any one reading over the accounts published by Dr. Smith, of Geneva, N. Y., some twenty years ago, of Mr. Ingalls, of Liverpool, England, Dr. Wilson, of Edinburg, and Professor Barlow of their various dialytic instruments and of Dr. Blair, of Edinburg of his third lens, would think from what they say of them there was nothing to be desired. All the said lenses are reported to be even when used under high power, perfectly free from aberrations, either chromatic or spherical, etc. and if so what became of them, for although they were, some of them, of eight or nine-inch aperture; we never hear of them again.

Mr. Wray, a celebrated English maker pursued the matter most perseveringly, he constructed one of nearly 20 inches aperture, but was obliged to confess, as indeed any one may see who will go to work and trace the rays through geometrically, that nothing could be done with the oblique rays, although he went to great trouble in making special eyepieces for it. So that he at length gave it up. Many others have tried with no better success. Then the difficulty of proper adjustment would be very great and of keeping the various surfaces, in proper ajustment, still greater, to say nothing of the trouble and expense of figuring and testing at least 5 surfaces. So that one may well ask where would the saving come in? It would be, not a simplified achromatic, but rather a highly complicated reflector and that is really all there is to it.

CAMDEN, N. J.

Sept. 8, 1900.

E. M. TYDEMAN.

An Interesting Phase of the Recent Solar Eclipse.-One of the most noticeable features of the recent solar eclipse was the rapidity with which the light returned after totality. At one minute after totality the landscape was quite as bright as it was at 10 minutes before totality. It would naturally be supposed that the gradation from sunlight to darkness and from darkness to sunlight would be the same before and after totality. But this did not seem to be the case. The difference was so mark :d as to preclude any theory of “illusion" or of "effect of contrast," there was no doubt in the writers mind that it was a real appearance. Other observers, when questioned, testified to the same effect. Miss Bacon, of the British Astronomical Asso., observing in this country, noticed the same appearance, and made particular mention of it in her report, remarking that "there is at present no theory that will account for this phenomenon, which is not at all what might be expected. This point alone will afford food for speculation and research." The text-books do not mention the phenomenon, nor is there any explanation of it in the recent astronomical journals.

With a view of bringing this question up for solution or discussion the writer wishes to advance the following theory of the phenomenon and believes that it is due to the inclination of the Moon's shadow to the Earth's surface. The accompanying diagram will illustrate the theory.

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In the diagram S is the eclipsed Sun, A, B and C the observer's position at forenoon, noon and afternoon respectively, the lines drawn from S to A, B and Care the Moon's shadow, the dotted lines indicate the horizontal view and Z the zenith at the various positions, the arrow indicates the direction of the Moon's shadow over the earth's surface.

When the observer is at A, where the totality occurs at about 9 o'clock in the morning, the Sun will be in the east about half way to the zenith and the Moon's shadow will stretch across the zenith to the west, thus covering about threefourths of the observers sky, leaving only one-fourth of the sky in the sunlight. As the shadow approaches, the light will fade rapidly before totality. When the shadow has passed the observer's position, and he is in a position corresponding to A', and the Sun begins to be uncovered, it will be seen that three-fourths of the sky will be in the sunlight, and only one-fourth in the shadow. This will cause the light to increase rapidly, which corresponds to the observations above stated.

When the observer is at B the Moon's shadow will be in the zenith and the illuminated sky will be the same at a given time before and after totality. Therefore the light should fade and return in about the same way before and after totality.

When the observer is at C, when the totality is at 3 o'clock in the afternoon, the effect should be opposite to that of the observer at A, and the light be greater before than after totality. The Sun will then be in the west about half way to the zenith; but the moon's shadow will cover only about one-fourth of the observer's sky, leaving three-fourths in the sunlight. This will cause the light to fade slowly before totality. After the shadow has passed, and the osberver is in a position corresponding to C', three-fourths of the sky will be covered by the shadow leaving only one fourth of the sky in the sunlight. This will cause the light to return slowly.

At all stations between A and B, the effect should be the same as at A, b it in a less marked degree, and in the same way at all stations between B and C, the effect should be the same as at C, though in a less marked degree. The nearer the observer is to noon at totality the less will be the gradation of light and shadow before and after. The farther the observer is from noon at totality the greater will be the contrast before and after totality.

It may be remarked, in conclusion, that in the case of the recent eclipse no observations were made at the noon period-that occurring in the Atlantic Ocean but there were numerous observers in the afternoon, though not many in the late afternoon, where the contrast would be great enough to attract attention. It would be well for future observers of total eclipses to pay some attention to this feature, so that more light may be thrown upon this interesting question. BROOKLYN, N. Y.

September 10, 1900.

A. J. B.

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