Fig. 400.
Fig. 401.
Usually only six stars in this cluster can be seen with the naked eye, and this fact has given rise to the legend of the "lost Pleiad." On a clear, moonless night, however, a good eye can discern seven or eight stars, and some observers have distinguished as many as eleven. Fig. 400 shows the Pleiades as they appear to the naked eye under the most favorable circumstances. Fig. 401 shows this cluster as it appears in a powerful telescope. With such an instrument more than five hundred stars are visible.
344. Cluster in the Sword-handle of Perseus.—This is a somewhat dense double cluster. It is visible to the naked eye, appearing as a hazy star. A line drawn from Algenib, or Alpha of Perseus (338), to Delta of Cassiopeia (330), will pass through this cluster at about two-thirds the distance from the former. This double cluster is one of the most brilliant objects in the heavens, with a telescope of moderate power.
Fig. 402.
345. Cluster of Hercules.—The celebrated globular cluster of Hercules can be seen only with a telescope of considerable power, and to resolve it into distinct stars (as shown in Fig. 402) requires an instrument of the very highest class.
