As an indication of the dissimilarity of the drawings of the Corona made at the same instant by different observers, many of whom are well-known astronomers, I may say that the various plates resemble in turn the following objects: a skate's egg-case; a circular battery discharging fire from one side while the smoke drifts away in the opposite direction; an ascidian, known as Molgula, with an extra aperture, however; a snowshoe; a radiolarian; a fighting shield of an Igorrote savage; an egg of a hair worm; a crushed spider, and other equally dissimilar objects. I have reproduced a few of these drawings (Plate II), that the reader may realize that my similes are not exaggerated. The many drawings which have been made of the Nebula of Orion, by astronomers of distinction, depart quite as widely from each other as do those of the Solar Corona. In Volume XXV of the "Naval Observatory Observations" is published a monograph of the central parts of the Nebula of Orion, by Professor E. S. Holden. He starts with a drawing made by Huyghens in 1659 and ends with a drawing made by Professor Langley in 1879. In a summary of the work the author says: "I am acquainted with but one drawing of the Nebula which is entirely above criticism, that of the late G. P. Bond. He was a skilled artist," etc. An examination of the drawings in this Memoir are equally distracting. In looking at them casually they suggest respectively a Japanese stocking pattern; an amoeba; an embryo cuttlefish; a plan of Boston, and other forms equally divergent. Mr. Fison, in his book above quoted, writes as follows of other astronomical subjects: "Drawings of the Milky Way as seen by the naked eye have been recently executed by two independent observers, Mr. Boeddicker and Mr. Eaton, each drawing the result of long and arduous observation, but in comparing them it is the exception rather than the rule to find any approximation in agreement in respect of the more delicate details." The drawings of the surface features of Mars by different observers do vary in respect of the more delicate details, but in every case they represent a map of some kind and do not remind one of a wheelbarrow, baptismal font, or other incongruous objects. These divergent drawings of the same object are not confined to celestial bodies. One has only to examine works on ancient Mexican and Egyptian monuments, or those of classical archæology, to see the astounding caricatures and perversions. The various drawings of the famous Dighton Rock inscription, covering a period of two hundred years, are striking examples of the vagaries of an artist. Moreover, the text accompanying the drawings often states that they were drawn with scrupulous care. The hieroglyphics are pecked out on the face of a rock in rough lines, half an inch wide and a third of an inch in depth. These marks are in enduring rock; it is the observer and his imperfect drawing which is at fault. The Nebula