hazy, on which account I have deducted 20" from the observed time of the observation in deducing the longitude from it:-magnifying power 100. The 2d satellite was expected to emerge about 56 minutes after the 1st: after looking for it at least 4 minutes beyond the calculated time, I discovered that it had emerged in contactwith the 1st. 15th. Emersion of the 3d satellite of Jupiter, observed at 9h 45' 8" mean time, or 9" 49′ 7′′ apparent time: night clear, -magnifying power of the telescope 100. 29th. Emersion of the 1st satellite of Jupiter, observed at 8 40 4" mean time, or 8h 43' 7" apparent time:-night clear, magnifying power 100. June 4th. In the evening, the moon occulted two small. stars in () Cancer. The last immersion took place so near to the extremity of the moon's southern limb, that it did not appear probable the moon's disk would extend 30" south of the star.-In each of these occultations, the stars appeared plainly defined on the edge of the moon's disk some seconds before the occultations took place:-in the last case, the star, by being so near to the southern extremity of the moon, appeared to be in contact with her limb for nearly 10 seconds, and for an equal space of time defined on the edge of the disk. 5th. Emersion of the 1st satellite of Jupiter, observed at 10 34′ 55′′ mean time, or 10" 36" 53" apparent time. The night clear, but the belts were scarcely visible, and the limb. of the planet uncommonly tremulous: magnifying power 100. 21st. Emersion of the 1st satellite of Jupiter, observed at 8 52′ 41′′ mean time, or 8h 51′ 26′′ apparent time: the planet and satellites well defined, magnifying power 100. July 14th. Emersion of the 1st satellite of Jupiter, observed at 9h 51 22′′ mean time, or 9" 0' 0" apparent time. The planet was so low and tremulous that the belts were not discernible:-magnifying power 100. This observation, as well as L those of May 6th, and June 5th, are not to be considered as so accurate as some of the others. Sep. 11th. Observation on the end of a lunar eclipse.. Longitude west from Greenwich by the eclipses of the satellites of Jupiter, as deduced from the tables of Mr. Delambre, and the British nautical almanac. Note. The observations made on the eclipses of the 1st satellite on May the 6th, June 5th. and July 14th, are to be considered as doubtful:-see the entries in the preceding journal on those days. 5 4 47 55 9 55 1 5.5 8 54.39 Longitude deduced from the lunar eclipse of Sept. 11th. If the time when the moon began to leave the earth's shadow be taken for the end of the eclipse, the longitude will be If the time of the moon's leaving the penumbra be taken for the end of the eclipse, the longitude will be h West fro m Mean, 5 4 16 5 3 50 By our maps, the borough of Lancaster appears to be about 4' 29" in time, west from the city of Philadelphia, which added to 5h 0" 37", the longitude of the latter west from Greenwich, will give 5" 5' 6" for the difference of meridians between the borough of Lancaster and the observatory of Greenwich; which differs but 24" in time from the mean of the six lunar observations, and only 59" in time from the widest of them. From this it is manifest, that very great dependance may be placed in the lunar observations, for the determination of the longitude. In determining the longitude from lunar observations, we have the advantage of increasing the number almost at pleasure, and rendering them so numerous, that the mean of all the results shall be nearly as accurate as the lunar theory itself, which seldom errs so much as 30" of a degree, and generally much less. By looking over the longitudes as deduced from the eclipses of Jupiter's satellites, it will be seen that the results from Delambre's tables are much more uniform than those from the nautical almanac, particularly of the 1st, 3d, and 4th satellites; with respect to the 2d, the nautical almanac appears to have the advantage; but it is to be remembered, that the observations made at this place have been too few, and the period too short, to decide on a subject of such nicety: it is nevertheless probable, that when the period is extended, and the number of observations increased on the eclipses of the 2d satellite, that Delambre's tables will be found to be the most accurate. If a mean of the longitudes deduced from the lunar observations, the eclipses of Jupiter's satellites agreeably to Delambre's tables, and the lunar eclipse be taken collectively, the longitude of Lancaster will appear to be 5" 5' 0".6; and if a mean of the eight good observations on the eclipses of the 1st satellite of Jupiter be taken, the longitude will be 5" 5' 7".3 which exceeds the longitude as taken from our maps but 1".3 and that of a mean of the whole collectively but 6".7. From which it appears, that the longitude may be considered to lie between 55 0."6, and 5" 5' 7".3 west from Greenwich, without the possibility of a material error: I shall therefore for the present call it 5" 5' 4". Observation on the going of the Clock. The pendulum-rod of the clock is made of wood, as being the most convenient for transportation, and not so liable to accidents as the gridiron-rod in removing the clock from one place to another, in which way it has heretofore generally been used. It was formerly supposed that wood neither expanded, nor contracted, in the direction of the grain, with heat and cold; but this is not strictly true, though the alteration appears much less than from wet and dry. When the atmosphere continues for some time equally saturated with moisture, the clock has always been found to go very regularly, notwithstanding the great and sudden changes we experience in the United States, from hot to cold, and from cold to hot. But the atmosphere being charged at different times, with different degrees of moisture, has a considerable effect, provided those changes from wet to dry, and the contrary, are of sufficient duration : for it requires several days' continuance of a damp, or dry atmosphere, to produce any sensible effect. I have observed for several seasons, that when the weather became warm in the spring, the motion of the clock was accelerated; the contrary would have been the case, had the pendulum-rod consisted of one single bar of metal, because it would have expanded or lengthened, as the weather became warm; but from the motion of the clock being accelerated, it is evident that the pendulum-rod must have contracted, and this was probably occasioned by the dry atmosphere, and drying winds, so prevalent at that season of the year, in this country. It does not appear from the experience of several years, that the clock would vary more than 12 seconds per diem, with the extreme changes of winter and summer, and wet and dry in our climate; when a single rod of iron would produce a change of 22 seconds per diem, and one of brass Hence a conclusion may be drawn, that wood (though far from being perfect) is preferable to a single rod, either of iron, or of brass. 34. I am, with great esteem, your sincere friend, and humble servant, ANDREW ELLICOTT. No. XIV. Notices of the Natural History of the northerly parts of Louisiana, in a letter from Dr. John Watkins to Dr. Barton. Read Jan. 1st, 1803. DEAR SIR, St. Louis, Ilinois. Octobr. 20th, 1802, In the note which you gave me some time ago, relative to some of the animals, larger trees and shrubs, that are to be found on the west side of the Mississippi; you requested me, that as the questions were made without much regard to order, to trouble myself as little as possible about the arrangement of my answers. I shall therefore proceed, in the spirit of that request, and in the plainest manner, without regard to any particular arrangement, mention such of those animals, trecs, and shrubs, as are here to be met with; and state to you as nearly as I can the part of the country where they most abound. The red fox (canis vulpes) is not known in this part of the country, or any where on this side the Mississippi, immediately |