out of the cage and put in a finch, which had also been taken from the
nest, but was reared far from such a machine, and he was frightened and
did not reconcile himself to it for some time. I exchanged this bird for
a goldfinch which had been caught after he was full grown, and his alarm
at the little mill was so great that he did not dare to move.

In a ground floor room which I used as my study, I hung an old sheet,
which reached to the ground, on a long spear inserted in a heavy wooden
disk; I surmounted it with a ragged hunting cap, and so arranged the
sheet as to give it some resemblance to the human form. When my dog came
in as usual, he looked suspiciously at the object, snuffing about and
gradually approaching to walk round and observe it. At last he was
satisfied, and curled himself up by the skirts of the bogey, where I had
placed the mat on which he was accustomed to lie when he was with me.
One evening when the moon shone doubtfully and there was just light
enough to distinguish the outline of things, I carried the shapeless
bogey into the garden near my room, and placed it among some shrubs and
bushes. I went back to the house and called my dog, who followed me
quietly until he reached the spot from which he could see the bogey
distinctly enough for him to recognize its identity with the one with
which he was already familiar. As soon as he saw the apparition he
stood still, growling furiously; he began to bark, and when I encouraged
him to come on, he turned round and ran back to the house. I shut up the
dog in another room, brought back the bogey to its former place, and
threw a strong light upon it before recalling the dog. At the first
sight of the bogey the dog paused suspiciously for an instant, but when
I sat down to the table as usual, he hesitated a little and after
snuffing at it went back to his couch.

I have made similar experiments with dogs, rabbits, birds, and other