Among those interesting objects, the variable stars, are several which may be well observed without optical assistance. Of these may be mentioned Algol, of which all the fluctuations of light may be easily observed with the naked eye; Mira Ceti, which may be well observed when at its brightest; Lambda Tauri, a variable star of the Algol type; Betelgeuse (Alpha Orionis), which is slightly variable; Zeta Geminorum, a fourth magnitude star, which varies about three-quarters of a magnitude in a period of about ten days; R. Hydræ, which is visible to the naked eye at maximum; Beta Lyræ, period about thirteen days; Eta Aquilæ, period about seven days; and Delta Cephei, which varies about one magnitude in a period of a little over five days. Of all these stars useful observations may be made without optical assistance of any sort. Observations, and even discoveries, of new or “temporary” stars may also be made with the naked eye. This occurred in the case of the “temporary” stars of 1572, 1604, 1670, 1866, and 1870, but, of course, these were bright objects at the time of their discovery. Hind’s “new star” of 1848 in Ophiuchus was, however, only of the fifth magnitude when it appeared, and it might have escaped detection with the naked eye. A star of this magnitude might, however, be easily detected by an observer who is familiar with the principal stars of a constellation. The Milky Way may, perhaps, be better seen with the naked eye than with any instrument, although an opera-glass brings out well, in some places, its more delicate details. A mere passing glance might lead a casual observer to suppose that the Galaxy stretched as a band of nearly uniform brightness across the heavens. But good eyesight, careful attention, and a clear sky will soon disclose numerous details previously unsuspected; streams and rays of different brightness, intersected by rifts of darkness, and interspersed with spots and channels of comparatively starless spaces. An excellent drawing of the Milky Way—the result of five years’ observations with the naked eye alone—has recently been completed by Dr. Otto Boeddicker at Lord Rosse’s observatory in Ireland. This beautiful picture is exquisitely drawn, and shows a wonderful amount of detail. A writer in the _Saturday Review_ of November 30, 1889, says: “His maps are in many respects a completely new disclosure. Features barely suspected before come out in them as evident and persistent; every previous representation appears, by comparison, _structureless_.” This shows what can be done with the naked eye in the study of this wonderful zone.