The brief assumption of splendor on the part of a comet is very unlike its usual humdrum existence when it is as yet so far distant as to be not only invisible to the comet-hunter, but beyond range of the far-reaching eye of the telescope or the entrapping power of the camera. Not the slightest impression is made on the photographic plate, and as far as an observer on planet earth is concerned the comet might have ceased to exist. It is only when it begins to draw near to the sun that we are enabled to obtain a record of the marvelous changes produced in its appearance, until at its nearest approach it has sometimes been known to vibrate as though with intense excitement. For instance, in the case of Biela’s comet, concerning which a special account is given further on, it was apparently so overcome at its last appearance in 1846, that it split in two and literally went to pieces. Quite a different story is told concerning the magnificent comet which greeted us in the summer of 1858, and was first seen at Florence on the 2d of June by Giambattista Donati, after whom it was named. At the time it was merely a nebulous mass about one-twentieth the diameter of the moon, and for some weeks it retained about the same brightness except for a gradual increase in the central star-like point, the only indication of its coming splendor. At the end of August it had increased so rapidly in brightness that by September it was visible to the unaided eye, resembling a hazy-looking star adorned with a small tail. Gradually, as it drew nearer to the sun, it increased in size and splendor, reaching its maximum brightness in October. Its train extended over an arc of forty degrees, or eight times the distance separating Alpha and Beta—the so-called pointers in the constellation of Ursa Major, the Great Bear. Its real length was then about forty-five million miles, with a width of ten million. The nucleus varied in diameter from five hundred miles to three thousand, or nearly half that of our planet earth. The comet was kept under accurate observation for fully nine months, and during part of that time it was visible to the naked eye. Professor G. P. Bond, the director of the Harvard College Observatory, availed himself of the opportunity thus presented, of making a series of drawings of the comet which convey an excellent idea of its changing appearance, and the delicate shadings and misty outlines of this marvelous visitant from the star-depths. These drawings are of all the more value, since it will be nearly two thousand years before Donati’s comet visits these realms again.