Page:The wonders of optics (1869).djvu/75

 imagining that the air was full of troops of cavalry, and whole armies even; such illusions resulting simply from the shadows of men and horses passing over an opposite mountain being thrown on the fog.

A vast number of different circumstances give rise to these illusions, such as a strong impression, or the recollection of some striking event, which may easily cause them, by the association of ideas. Wigan relates, that being at a soirée held at the house of M. Bellart, a few days after the execution of Marshal Ney, the groom of the chamber, instead of calling out the name of M. Maréchal aîné (M. Maréchal, senior), announced the arrival of M. le Maréchal Ney. A shudder passed through the company, and many of them declared, that for an instant they saw the face and figure of the dead man in place of those of his involuntary representative.

When the mind is thus prepared, the most familiar objects are transformed into phantoms. Ellis relates an anecdote of this kind, which he heard from an eye-witness, who was a ship's captain of Newcastle-on-Tyne. During a voyage that he made, the ship's cook died. Some days after the funeral, the chief mate came running to him in a great fright, with the news that the ship's cook was walking on the water, astern of the vessel, and that all the crew were on deck looking at him. The captain, who was angry at being disturbed with so nonsensical a tale, answered sharply, that they had better put the ship about and race the ghost to Newcastle. His curiosity, however, was presently aroused, and he went upon deck and looked at the spectre. He frankly avowed that for some moments he saw what really appeared to be his old shipmate, just as he knew him in life, with his walk, clothes, cap and figure perfectly resembling those of the dead man. The panic became general, and every one was struck motionless for a time. He had the presence of mind, however, to