SAGACITY OF A DOG. — Some short time since a achild of Mr. An. Munn, of Letterkenny, about three years old, fell into a vessel of water in the rear of the house, and it would in all probability have perished had it not been for a dog, which promptly ran to his assistance, and after having rescued him from his perilous situation, set up such a strange howling as attracted the notice of one of the family, who on arriving found the dog still holding the little boy by the clothes, lest he might again fo in the water. The dog, on resigning his charge in safety, manifested strong symptoms of joy, leaping and wagging his tail in apparent delight. The same animal was the means of preserving the life of a man a few years ago, in the vicinity of Doe Castle, who had sunk when bathing in a place so dangerous that no person would venture to his aid; he had gone down the second time when the dog plunged in after him, seized him by the hair, and ultimately brought him to where assistance was available. He is a water-dog of the Newfoundland kind. — Derry paper