h. m. S. 1889, June 18; Eclipse of Satellite III. 13 30 22; the satellite has a round disc, power 390, seeing Wt. 2. 13 42 52; the satellite appears to be flattened on the following side. 13 44 18; about half the disc of the satellite is obscured, 13 45 20; exactly half the disc is obscured as nearly as can be seen. 13 46 32; disc like a half moon. 13 53 9; disappeared. A curious green patch on the middle belt of Jupiter. (See drawing of this date by J. E. K.) E. S. H. h. m. S. 1889, June 19; Transit of Red Spot. 12 56 29; the preceding end of the red spot is barely past the centre of the disc. E. S. H. 1889, July 2; Occultation of Satellite I 13 26 56; contact I, 13 29 25; bisection, 13 32 15; contact II, Wt. 2, seeing poor. The satellite was seen inside the limb as a very brilliant stellar point and disappeared just at second contact. E. S. H. 1889, July 3; Transit (Egress) of Satellite I and its Shadow. h. m. 12 30 S. 12 36 22; 12 39 32; the shadow is round, color brownish black. The satellite is brilliant; a little more so than the tops of some white clouds on the same reddish belt (north part of main belt). satellite elongated east and west. major axis of satellite I 11⁄2 times minor axis, and inclined 5° to 10° to Jupiter's equator in direction s. p. and n. f. 12 40 22; the shadow slightly elongated in same direction. 12 42 7; major axis of satellite parallel to Jupiter's equator; shadow as before. 12 47 32; 12 47 6; internal tangency of limbs of Jupiter and satellite I. satellite is twice as long east and west as north and south. first appearance of any part of the satellite outside the limb of Jupiter. 12 48 38; 12 50 49; bisection of satellite. h. m. S. 12 53 57; external tangency of satellite. The time from bisec tion to second contact is more than the time from first 12 55 14; free space between satellite and limb. 13 0 40; 13 2 49; first contact of shadow. 13 4 7; shadow bisected. 13 442;. notch perfectly round; well seen. As may be seen by comparing the times of contacts and of bisections the observations are uncertain on account of poor seeing and low altitude. For the same reasons the apparent changes in the shapes of the satellite and shadow are doubtful from this night's observations. E. S. H. h. 1889, July 7; Transit of Shadow of Satellite II; Transit of Shadow of Satellite IV. Wt. 3. 9 56 57; shadow of IV makes a notch in the north limb equal to 34 of the diameter of the shadow. Satellite IV looks circular. ΙΟ IO ΙΟ ΙΟ 2 17; the shadow is elongated; it major axis points slightly west of the centre of Jupiter. It is still a notch in the limb. It seems to have a penumbra about it. 3 —; the width of the penumbra is 1/4 of the diameter of the satellite. 8 7; the shadow is a little east of the north end of Jupiter's axis. 9 27; still a notch; 34 of its diameter inside the limb of the planet. IO IO 22; the shadow is on Jupiter's axis. The axis of the shadow points a little west of Jupiter's centre. h. m. S. 10 17 34; shadow of IV is at least twice as large as that of II. The centre of shadow of IV is much darker than the shadow of II. The shadow of II has a penumbra [drawing]. IO 25 27; the disc of IV is certainly circular. I think there are markings on it, but the vision is not good enough to be certain. 10 34 the longest axis of shadow of IV now appears to be parallel to the axis of Jupiter. 10 39; the shadow of IV is about bisected; its longest axis seems to point east of Jupiter's centre. 10 50 57; the shadow of IV (projected on the olive-grey near north pole) has constantly been darker than the sha dow of II (projected on a white belt just north of the red equatorial belt). 10 52 27; the shadow of IV still makes a rounded notch. Probably not more than 4 of it is on the planet. 10 55 57; the shadow of IV is a faint undulation in the limb. 10 57 27; ditto. IO 58 57; ditto. II 0 57; shadow of IV no longer visible. II 59 II is quite bright; three of its own diameters from the limb. 12 6 18; internal contact of II. 12 9 12; satellite about bisected. 12 9 39; satellite bisected. 12 12 9; about last contact. 12 12 54; last contact of II. The disc of II is all outside and it seems not more than 1⁄2 the diameter of I. ; II seems to increase in brightness all the time. ; II seems at least twice as bright as when fairly clear of the limb. (Contrast? atmosphere of planet?) E. S. H. Colors of the Satellites. I is fiery yellow, E. S. H.; same as III, J. E. K.; redder than III, E. S. H. III is strong yellow, E. S. H.; golden yellow, J. E. K. IV is pale lemon yellow, E. S. H.; a pale yellowish white, J. E. K. h. m. S. 1889, July 11; Transit of Red Spot. 11 32 9; red spot central. II 37; red spot certainly past transit. On this night (and on subsequent occasions) attempts were made to measure the distance apart of two objects on Jupiter (a) at or near the limb (b) at the centre, with the object of comparing the effect of Jupiter's atmosphere in the two cases. When the planet is higher, I think this can be done, but I have had no success during the present opposition. E. S. H. h. m. 1889, July 11; Eclipse (reappearance) of Satellite II. S. 12 19 24; first glimpse of II. 12 23 15; satellite seems to be of full brightness. The disc is round. The outline of the shadow of Jupiter is not seen on the disc of II. At 12h 19m 24 the satellite was just barely visible-say 17 magnitude, and it gradually increased in brightness till 12h 23m, and very likely even after that time. E. S. H. 1890, August 17. Dark markings on Jupiter's satellite III. The seeing was average. Eye-pieces 360 and 520 were employed. No markings were seen at any time on satellites I, II, IV. At 9" 55" P. s. t. a dark marking was seen by E. S. H. on III, extending from the centre to the north limb. The marking was all to the east of a north and south diameter. It was seen (and independently drawn) by W. W. C. exactly as by E. S. H., except that for W. W. C. it terminated before reaching the north limb. Its greatest dimension east and west was 4 of the diameter of III. There is no doubt whatever regarding its existence. At 11h 40TM P. s. t. both observers are certain that the marking is further south and further east on the disc. The shape of the marking not so well seen as before. If the spot is a part of the surface of III and turns with it, the rotation period of this satellite is short. E. S. H. and W. W. C. THE OBSERVATORY OF THE U. S. MILITARY ACADEMY AT WEST POINT, N. Y. Memorandum by Lieut. F. S. HARLOW, U. S. A. (in charge). "The permanent observatory at the Military Academy is provided at present with a REPSOLD Meridian Circle, a CLARK Equatorial, and a BOND Chronograph used in connection with a HOWARD mean time and a HARDY sidereal clock. "The circle is 26 inches in diameter, graduated to 2', and reads directly to 1" by means of four reading microscopes fitted with micrometers. Each micrometer screw carries two pairs of parallel wires. "The telescope has a free aperture of 7 inches, a focal length of 81.5 inches, and is provided with five positive eye-pieces of powers 70, 150, 210, 280, and 350, together with two sunglasses, and the R. A. and Declination micrometers. The reticle carries 23 transit wires. For use with the nadir basin a reflecting nadir cap is provided. The illumination of the several microscopes and of the main field is in accordance with the REPSOLD design. "Two collimators are mounted on piers in the meridian. Free aperture, 3 inches. Focal length, 38 inches. m "The CLARK Equatorial has a free aperture of 12 inches, and a focal length of 15 feet. Powers of the negative eye-pieces, 150, 300, 600, and 1200. The declination circle is graduated to 10', and is provided with two verniers read by micrometer microscopes directly to 10". The hour circle is graduated to 1 and reads by verniers to 1. These circles are all illuminated by small incandescent lamps in connection with a battery of 4 or 5 bichromate cells. The filar position micrometer has 3 positive eye-pieces of powers, 110, 155, and 210, and the wires are illuminated by electricity. "The equatorial is also fitted with a telespectroscope,' in which two gratings are used, one on speculum metal by RowLAND, with 14438 lines per inch, and one on glass by RUTHERFORD, with 17100 lines per inch. "The electric connections of the BOND chronograph provide for switching either the mean time or sidereal clock, and either |