What precedes their appearance?
The rattling of chains, groans, sighs, because there is nothing very cheerful in all that?
They are careful not to appear in the bright light, or after a strain of dance music.

No, fear is an abyss into which you descend step by step, until you are overcome by vertigo; your feet slip, and you plunge with closed eyes to the bottom of the precipice.
Now, if you read the accounts of all these apparitions, you'll find they all proceed like this: First the sky darkens, the thunder growls, the wind howls, doors and windows rattle, the lamp--if there is a lamp in the room of the person the ghosts are trying to frighten--the lamp flares, flickers and goes out--utter darkness! Then, in the darkness, groans, wails and the rattling of chains are heard; then, at last, the door opens and the ghost appears.

I must say that all the apparitions that I have not seen but read about have presented themselves under similar circumstances.

Isn't that so, Sir John ?" "Perfectly." "And did you ever hear of a ghost appearing to two persons at the same time ?" "I certainly never did hear of it." "It's quite simple, my dear fellow.

Two together, you understand, have no fear.