No. XXXVIII. Continuation of the Astronomical Observations made at Lancaster, in Pennsylvania, by Mr. Andrew Ellicott. Read October 18th, 1805. Note:-The eclipses of Jupiter's Satellites were all observed with an achromatic telescope magnifying about 100 times. 1804. March 11th. Immersion of the 2d satellite of Jupiter observed at 12 9′ 11′′ mean time, night clear. May 13th. Emersion of the 1st satellite of Jupiter observed at 8 30′ 20′′ mean time, night clear. 20th. Emersion of the 1st satellite of Jupiter observed at 101 25′ 14′′ mean time, night clear; but from the proximity of the moon to the planet, it is probable that the emersion was observed 9 or 10 seconds too late. 22d. Emersion of the 3d satellite of Jupiter observed at 9 45′ 50′′ mean time, night clear. June 5th. Emersion of the 1st satellite of Jupiter observed at 8 43′ 1′′, mean time, a little hazy. 28th. Emersion of the 1st satellite of Jupiter observed at 8° 56′ 5′′ mean time, a little hazy. July 4th. Emersion of the 3d satellite of Jupiter observed at 9 37′ 56′′ mean time, a little hazy. 1805, January 14th. Observations on a lunar eclipse. >'s limb began to be obscured at 13° 45′ 42′′ The end of the eclipse, and of total darkness. could not be observed on account of a snow storm. April 30th. Immersion of the 1st satellite of Jupiter observed at 10 54' 23" mean time, night clear. June 1st. Emersion of the 1st satellite of Jupiter observed at 9 37′ 19′′ mean time, night clear. 2d. Emersion of the 2d satellite of Jupiter observed at 9" 19′ 3′′ mean time, night clear. 26th. Observations on the beginning of a solar eclipse. The afternoon was remarkably clear and serene, but the sun being low, his limb was very tremulous, though not so much so as.to occasion an error of more than 5 or 6 seconds.-My eye was directed to the precise spot where the eclipse began, which was observed at 6" 45′ 48′′ mean time, or 6 43′ 26′′ apparent time. The beginning of this eclipse was observed by Mr. Patterson in Philadelphia, at 6 47' 40" apparent time. The longitude of Lancaster by the above eclipse appears to be 54′ 19′′ west from Greenwich, which is 47" less than I have stated it from the result of a considerable number of the eclipses of Jupiter's satellites, and some lunar distances.-The longitude of the city of Philadelphia, by the same eclipse as observed by Mr. Patterson, appears to be 4 59′ 33′′ west from Greenwich; which is about 1' 4" less than it has been settled by a great number of corresponding observations made there, and at the royal observatory of Greenwich. This difference, no doubt principally arises from the imperfection of the lunar theory, and probably much the greater part of it from the errors in the moon's latitude. July 4th. Emersion of the 2d satellite of Jupiter observed at 8 55' 4" mean time, night clear. 10th. Emersion of the 1st satellite of Jupiter observed at 8h 9' mean time, twilight very strong. 11th. Emersion of the 2d satellite of Jupiter observed at 11 29′ 38′′ mean time, night clear. 17th. Emersion of the 1st satellite of Jupiter observed at 104′16′′ mean time, night clear. 26th. Emersion of the 3d satellite of Jupiter observed at 8" 22′ 39′′ mean time, twilight very strong. August 2d. Emersion of the 1st satellite of Jupiter observed at 8 23' 9" mean time, twilight very strong. 2d. Immersion of the 3d satellite of Jupiter observed at 10h 5′ 5′′ mean time, night clear. 9th. Emersion of the 1st salellite of Jupiter observed at 10" 18′ 20′′ mean time, a little hazy. September 6th. Emersion of the 2d satellite of Jupiter observed at 8 18' 9" mean time, very clear, but the planet tremulous. * The person who noted the time, had some doubts whether this should not be 54. 7th. Emersion of the 3d satellite of Jupiter observed at 8 23′ 15′′ mean time, very clear. By Mr. Delambre's tables, the longitude of Lancaster as deduced from each of the foregoing observations on the eclipses of Jupiter's satellites will stand as follows. 1804. March 11th. Immersion of the 2d satellite Longitude West 55 15 A Description of a Cave on Crooked creek, with Remarks and Observations on Nitre and Gun-Powder, by Samuel Brown, M. D. of Lexington, Kentucky. Read February 7th, 1806. THERE are few works on Natural History or Chemistry which do not contain some facts or opinions concerning the formation and properties of nitre. To recapitulate these facts, or to state the various theories to which they have given rise, would be a task very different from that which I have undertaken; which is merely to communicate a short account of some of the most remarkable caverns and rocks from which that salt is obtained in Kentucky; and to offer some conjectures relative to the causes of the imperfection of the gun-powder manufactured in the United States. The quality of the nitre procured from the earth in calcareous caverns, is universally believed to be different from that which is found in the sand rocks. I have not been able to ascertain, with any degree of precision, the quantity annually manufactured in this State, nor the number of caverns which are known to contain it. I have however visited several of the most remarkable of them and from the best information I could procure I have formed the following estimate. The great cave on Crooked creek, of Nitre. 1000000 200000 50000 20000 10000 a branch of Rock castle, supposed to contain Scott's cave, two miles distant from the great cave Davis's cave, six miles distant from the great cave Two other caves, within a mile of the great cave A cave on Rough creek, a branch of Green river Besides these, which I have had an opportunity of examining, I have heard of many others in various parts of the State; some of which are esteemed very rich in nitre, and are said to be of great extent. The great cave on Crooked creek in Madison county, is situated about 60 miles south east of Lexington. It has two mouths which are 646 yards distant from each other, and about 150 yards from a large creek, which winds round the hill through which the cave affords a commodious passage for horses and waggons. The general level of the floor of the cave is 80 feet above the creek. The average height of the arch is ten feet, though in many places it rises to fifty or sixty. The breadth of the passage is generally about forty feet, in some parts it is seventy or eighty feet. The floor has the appearance of a large public road, which has been much frequented. The ceiling is in most places smooth, with but few incrustations or stalac tites. In some of the chambers however there are appearances of Gothic rudeness and irregularity which are truly sublime. When these vast chambers are sufficiently illuminated by the torches and lamps of the workmen, they present scenes so uncommon and so romantic, that the most stupid beholder cannot contemplate them without expressions of the greatest astonishment. During the winter season the effect of these scenes is greatly increased by a stream of water which issuing from a small opening in the arch of the cave, about twenty feet above the floor and falling into a bason, occasions a noise which in these calm regions can be heard at great distance, and echoing from arch to arch, fills the mind with the idea of some mighty cataract*. The temperature of this cave, during the last winter (the coldest we have had for several years) was generally 52° of F. sometimes the mercury rose as high as 57° but never sunk to the freezing point, when the thermometer was placed at any considerable distance within the cave. In one chamber however, the heat was frequently so great as to be disagreeable. About sixty paces from the south entrance, a passage leading from the main avenue conducts you to this chamber, which is nearly circular and about twenty feet in diameter. The arch over this part of the main avenue and that over the passage leading to the warm chamber, are equally elevated. But the ceiling of the chamber is twenty or thirty feet higher. As you approach the chamber, the floor gradually rises until it ascends above the level of the arch of the passage. As soon as you ascend above that level, you perceive the air uncommonly warm, even when the temperature of the passage is near the freezing point. The air which fills the main avenue in summer and autumn is forced into this chamber, whenever the external atmospheric air becomes so much condensed by cold as This cave was discovered about seven years ago by a Mr. Baker. He entered it by the north mouth, but proceeded only a small distance into it, on the succeeding day he brought his wife and two or three of their children to explore it, he carried a torch and his wife a supply of pine. After they had advanced within hearing of this torrent 400 or 500 yards from the north mouth, the only one then known, he dropped his torch and it was completely extinguished. During two days and two nights this miserable family wandered in total darkness, without provisions and without water, though sometimes within hearing of a cataract which they durst not approach, at length Mrs. Baker in attempting to support herself on a rock, perceived that it was wet, she conjectured that this was caused by the mud which they had brought in on their feet, Baker immediately ascended the rock, and saw the light of day. |