Uranus and Neptune are difficult to observe spectroscopically, but appear to have peculiar spectra agreeing together. Sometimes Uranus shows Frauenhofer lines, indicating reflected solar light. But generally these are not seen, and six broad bands of absorption appear. One is the F. of hydrogen; another is the red-star line of Jupiter and Saturn. Neptune is a very difficult object for the spectroscope. Quite lately[7] P. Lowell has announced that V. M. Slipher, at Flagstaff Observatory, succeeded in 1907 in rendering some plates sensitive far into the red. A reproduction is given of photographed spectra of the four outermost planets, showing (1) a great number of new lines and bands; (2) intensification of hydrogen F. and C. lines; (3) a steady increase of effects (1) and (2) as we pass from Jupiter and Saturn to Uranus, and a still greater increase in Neptune. _Asteroids_.—The discovery of these new planets has been described. At the beginning of the last century it was an immense triumph to catch a new one. Since photography was called into the service by Wolf, they have been caught every year in shoals. It is like the difference between sea fishing with the line and using a steam trawler. In the 1908 almanacs nearly seven hundred asteroids are included. The computation of their perturbations and ephemerides by Euler’s and Lagrange’s method of variable elements became so laborious that Encke devised a special process for these, which can be applied to many other disturbed orbits.[8] When a photograph is taken of a region of the heavens including an asteroid, the stars are photographed as points because the telescope is made to follow their motion; but the asteroids, by their proper motion, appear as short lines. The discovery of Eros and the photographic attack upon its path have been described in their relation to finding the sun’s distance. A group of four asteroids has lately been found, with a mean distance and period equal to that of Jupiter. To three of these masculine names have been given—Hector, Patroclus, Achilles; the other has not yet been named. FOOTNOTES: [1] Langrenus (van Langren), F. Selenographia sive lumina austriae philippica; Bruxelles, 1645. [2] _Astr. Nach._, 2,944. [3] _Acad. des Sc._, Paris; _C.R._, lxxxiii., 1876. [4] _Mem. Spettr. Ital._, xi., p. 28. [5] _R. S. Phil. Trans_., No. 1. [6] Grant’s _Hist. Ph. Ast_., p. 267. [7] _Nature_, November 12th, 1908. [8] _Ast. Nach_., Nos. 791, 792, 814, translated by G. B. Airy. _Naut. Alm_., Appendix, 1856. 14. COMETS AND METEORS.