flesh of children to creep upon their bones, and make cowards of them where there is no reason for fear.  For you may lay it down as a fact, established beyond dispute, that not one of these things is a reality.  The person who tells these marvels has always what seems the best of reasons for his belief.  He either saw these things himself or knew somebody, strictly truthful, who had seen them.  He did not know, what I am going to prove to you, that a thing may be true and yet not be real.  In other words, that there are times when we do actually see marvels that seem supernatural, but that, on such occasions, we must not believe our own eyes, but search for a natural cause, and, if we look faithfully, we are sure to find one.

Once a vessel was sailing over a northern ocean in the midst of the short, Arctic summer.  The sun was hot, the air was still, and a group of sailors lying lazily upon the deck were almost asleep, when an exclamation of fear from one of them made them all spring to their feet.  The one who had uttered the cry pointed into the air at a little distance, and there the awe-stricken sailors saw a large ship, with all sails set, gliding over what seemed to be a placid ocean, for beneath the ship was the reflection of it.

[Illustration]

The news soon spread through the vessel that a phantom-ship with a ghostly crew was sailing in the air over a phantom-ocean, and that it was a bad omen, and meant that not one of them should ever see land again.  The captain was told the wonderful tale, and coming on deck, he explained to the sailors that this strange appearance was caused by the reflection of some ship that was sailing on the water below this image, but at such a distance they could not see it.  There were certain conditions of the atmosphere, he said, when the sun’s rays could form a perfect picture in the air of objects on the earth, like the images one sees in glass or water, but they were not generally upright, as in the case of this ship, but reversed—­turned bottom upwards.  This appearance in the air is called a mirage.  He told a sailor to go up to the foretop and look beyond the phantom-ship.  The man obeyed, and reported that he could see on the water, below the ship in the air, one precisely like it.  Just then another ship was seen in the air, only this one was a steamship, and was bottom-upwards, as the captain had said these mirages generally appeared.  Soon after, the steamship itself came in sight.  The sailors were now convinced, and never afterwards believed in phantom-ships.

A French army marching across the burning sands of an Egyptian desert, fainting with thirst and choked with fine sand, were suddenly revived in spirit by the sight of a sheet of water in the distance.  In it were mirrored the trees and villages, gardens and pretty houses of a cultivated land, all reversed.  The blue sky was mirrored there, too, just as you can see the banks of a lake, and the sky that bends