but this very brilliancy is inconvenient in the telescope, where it merely appears as a glare which renders all details invisible.

Fig. 5.—Comparative Sizes of the Planets. The great circle represents the Sun.

Beyond a few ill-defined and inconspicuous marks, nothing has ever been seen on this planet which is of any interest for our present purpose. Though clouds are comparatively an unimportant feature on Mars, they assume the most extraordinary importance on Jupiter. He is a gigantic body, by far