able weather has permitted. Its magnitude this evening seems to be almost exactly the ninth.

The position of the variable was at once seen to correspond very nearly with that of a star, No. 2765 of 26°, given by Argelander in his "Durchmusterung des südlichen Himmels." An observation of position, by means of a transit-instrument belonging to the Coast Survey, and temporarily in my possession, corroborated the impression that these stars were identical; and now that the variable has waned to the 9th magnitude, and no other small star is found to have been obscured by its excess of brilliancy, it is manifest that the original suspicion was correct. There seems to be no regular observation of the star's place on record.

The determinations of magnitude during the time of visibility to the naked eye are rendered easy by means of a yet unpublished uranometry of the region between the declinations +45° and -2°, prepared at the Dudley Observatory in Albany during the year 1858, in which the brightness of every star visible to the naked eye is given to the nearest tenth of a magnitude. This, however, affords the numerical values for no date subse quent to May 19; and the comparison-stars for later observations are still subject to some uncertainty, which may affect the determination for the variable by a tenth or possibly by twotenths of a magnitude. These will, however, be carefully determined before long by Mr. Chandler.

The Albany values for the brightness of the comparison-stars

M.

2.0 y Herculis,
2.38 Coronæ,

are these:

a Coronæ,

B Herculis,

8 Boötis,

For the variable, the magnitudes, as thus far determined by us,

Mr. Chas. A. Schott in Washington observed the star May 24 and 31, and estimated the magnitudes on those dates as 8·1 and 8.7 respectively.

Since first calling public attention to the sudden appearance of this remarkable star, I have received from many quarters information of its independent and, in several instances, previous detection; but only in a few cases do trustworthy determinations of its magnitude appear to have been made.

AM, JOUR. SCI.-SECOND SERIES, VOL. XLII, No. 124.-JULY, 1866.

Mr. Wm. M. Davis, Jr., of Philadelphia, saw the star on the evening of May 12, called the attention of his family and friends to the phenomenon, and noted in his journal that the star was as bright as a Coronæ.

Mr. Ferguson, of the Washington Observatory, writes that the star was seen on Sunday evening, May 13, by Mr. Farquhar of Washington, assistant to Prof. Schaeffer, who communicated the fact to Admiral Davis, superintendent of the observatory. Mr. Farquhar estimated the magnitude on the 13th inst. as the second; Mr. Ferguson observed the star on the 15th, and estimated it as then of the fourth magnitude.

Prof. Watson, of the Ann Arbor Observatory, sends me word that Mr. Barker, a gentleman in London, Canada, perceived the star about May 1, and described it as equal to & Coronæ in brilliancy at that time.

Prof. Henry Tutwiler, of Greene Springs, Ala., also detected the star on the 12th of May. For letters from him I am indebted to Robert Patterson, Esq., of Philadelphia, and to Prof. Henry of the Smithsonian Institution. He states that on that evening, it was somewhat superior in brilliancy to a Coronæ; and on other dates he observed or estimated it as follows: May 14th, 3d mag., somewhat brighter than Corona; May 17th, less bright than & Coronæ; May 19th, barely visible to the naked eye; May 20th, only perceptible through a small spy-glass, 8th mag.; May 24th, 10th mag. This last estimate must have been an extreme one, very possibly in hazy sky and without comparison-stars.

At an early day the star was also noted by Mr. Hallowell of Alexandria, who has very recently communicated his observations to a Philadelphia daily paper, but I have not yet been able to see them. Indirectly I have been informed that Mr. Hallowell has seen the star on previous occasions during the winter, which would imply that it has been fluctuating in short periods, since Mr. Chandler is positive that when he examined the region toward the close of April, the star was, to say the least, not conspicuous.

Mr. R. L. Knight, of Philadelphia, writes me that on the 23d of September last he saw, in the constellation of the Crown, a brilliant star, not laid down upon the maps, and that it was then equal to Gemma in brilliancy.

From these various data it would seem probable that the new variable which should, following Argelander's notation, receive the name T Corona, must have reached a magnitude of at least 1 at maximum, and that this maximum, perhaps only one of a series, occurred between the 5th and 12th of May.

P. S. June 12. The Astronomische Nachrichten of May 26, this day received, brings information of the detection of this star

in Ireland on the 12th, and in Rochefort, France, on the 13th of May.

On the 16th, Mr. Huggins and Prof. Miller made a careful observation of its spectrum,-the star being then a little below the 4th magnitude. Their inference was that the spectrum was double, consisting of one principal system of lines analogous to that of the sun; and, superposed upon this, a second one, apparently due to light emanating from intensely heated gaseous matter, containing, among other bands, two bright ones in the positions of the lines F and C, which correspond to hydrogen lines.

Mr. Courbebaisse, who observed the star at Rochefort on the 13th, states that he had seen no such star there on the 11th.

ART. XIV. On the Emery Mine of Chester, Hampden County, Mass., with remarks on the nature of Emery, and its associate minerals; by J. LAWRENCE SMITH, Pres't Louisville Gas Co.

CONSIDERABLE interest is attached to the recent developments of an extensive deposit of emery in Chester, Hampden county, Mass., by Prof. C. T. Jackson; and my name has been associated in various ways with it, without my having had any thing directly to do with it. Sundry communications have also been received by me from various parties. These communications are best answered by the facts embraced in this article, some portions of which it has always been my intention to publish without reference to the special interest of any one in the matter.

Prior to 1846, emery was simply known as a mineral, coming to us from a few remote localities, and was used in the arts without our having any knowledge of its true geological position or its mineralogical relations. About that period, circumstances favored my commencing those geological and mineralogical discoveries in relation to emery, that were afterwards embodied in two papers, presented to the Academy of Sciences of Paris, in 1850, in which the subject was thoroughly discussed, and I might say almost exhausted. The light in which those discoveries were considered will be seen by the conclusions of the report of the committee of the Academy, consisting of Messrs. Dufrenoy, Elie de Beaumont, and Cordier, viz:

"It results from the review just given of the labors of Dr. Smith, that he has made known

1st. The precise nature of the geology of emery in Asia Minor and the Grecian Archipelago;"

2d. "That he has described the properties of the principal minerals associated with it, and the manner in which they occur,

especially diaspore and emerylite; this last mineral forms, by the identity of its composition in the different formations that the author had occasion to study, a mica constituting a new species, and one well determined;"

3d. "Finally, that he has given a means for determining the qualities of emery, and consequently their commercial value; this process, eminently practical, offers, besides, an interest in a scientific point of view, inasmuch as it permits of determining the difference in the tenacity of minerals of equal hardness.

"These researches of geology, mineralogy, and of analytical chemistry, constitute a work of the highest interest, both as a whole, as well as from the new facts they promise to science. Your committee consequently propose to thank Dr. Smith for having communicated them to the Academy, and in consideration of the importance of the work, to order the insertion of his paper in the Receuil des Mémoires des Savants étrangers."

At that time I had discovered six new localities of emery in Asia Minor, and the Grecian Archipelago. Those localities were far removed from each other, and furnished so many different places for the study of emery and its associate minerals in addition to the old locality of Naxos; and consequently many points of general interest were brought out, besides others connected with the line of study. Those who may feel interested in the subject will find the investigation and results there arrived at in this Journal, vols. x and xi, 1850 and 1851; they embrace the geology, mineralogy, chemical composition, manner of mining, commercial considerations, associate minerals, &c.

The study of the associate minerals I considered of great importance, as they would be guides in future explorations in other parts of the world; and even prior to completing the researches on the subject I wrote to Professor Silliman and asked him to examine the American corundum localities for these minerals, one of them in particular, which he immediately did. With the corundum from the locality in Chester county, Penn., and Buncombe county, N. C., he "soon found the mineral indicated," and communicated the same to this Journal, Nov. 1849, pp. 379 and 383.

Nothing further came to my notice in relation to emery until I received from Prof. C. T. Jackson a letter dated Oct. 9th, 1864, containing what follows:

"You discovered emerylite or margarite in Asia Minor as an associate mineral with emery. On the 22d of October last, 1863, I discovered, while surveying an iron mine in Chester, Mass., some beautiful veins of the margarite, from half inch to two inches wide, and of a fine delicate rose color, or light pink. The nature of this mineral I did not discover until my return to Boston, but at first supposed it was lepidolite; on analysis it proved

to be margarite, and from that I ventured to predict the occurrence of emery, but no attention was paid to this prediction by the owners of the mine, who were more intent on the iron ore. A few weeks since, I saw Dr. Lucas, one of the owners, resident in Chester, and called him into my office, and explained to him the great value of emery, and told him how to detect it, and he promised to make the search I required, and took exact directions from me."

"The next day after his return to Chester, he found the emery, a big vein nearly six feet wide, which had been mistaken by him for iron ore, it being very magnetic. I write you this, to show you the importance of your discovery of the emerylite or margarite (for this appears to be identical), as an associate of emery, and also as an interesting case of deduction from scientific memoirs."

Accompanying the letter he sent me a paper giving me a summary of a communication he had made to the Boston Society of Natural History on the subject, concluding by remarking that "had not the occurrence of emerylite and chloritoid called his attention to the probable existence of emery at this locality, it would have been overlooked to this day, and no one knows how much longer. The fact was mentioned as an example of the real uses of supposed useless minerals; and the Doctor took occasion to express his obligations to Dr. Smith, of Louisville, for his valuable contributions to our knowledge of the associate emery minerals of the Grecian Archipelago and Asia Minor."

These statements are sufficient to show how far my geological observations served as a guide to Prof. C. T. Jackson, in his deductions with reference to the existence of emery in Chester, and with what diligence Dr. H. S. Lucas followed up the latter's directions, resulting in the valuable development of emery.

I have since visited the locality, having done so in the month of March last. The geological character and position of the rocks was not as well made out by me as might have been done in a more favorable season; but as my observations accord, as far as they go, with those of Dr. Jackson and Prof. Shepard, I prefer inserting their observations, rather than my own, in describing the geology of the emery locality.

"The mine is situated nearly in the center of the Green Mountain chain as it traverses the western border of the state, at a point not far from half way between the Connecticut and Hudson rivers. It is included in the metamorphic series of rocks, here consisting of vast breadths of gneiss and mica-slate, with considerable interpolations of talcose slate and serpentine. The general direction of the stratification is N. 20° E. and S. 20° W., the relation to the horizon varying from vertical, to a dip of from 75° to 80°, sometimes east, sometimes west.