This dark coloured water-rat, finding his position less and less secure at the adjacent barn on account of the attacks of the grey invaders, one fine day migrated, with Mrs Rat and all the Master and Missy rats, down to the stream. Peeping and sniffing about for a pleasant retreat, he chose the neighbourhood of the willow tree. I cannot stay here to discuss whether or no he was led to the tree by some mystic beckoning hand—some supernatural presentiment; but to the tree he went, and Stirmingham was founded. Two or three burrows—small round holes—sufficed to house Mr Rat and his family, but these ran right under the willow, and of course still further weakened it. In course of time the family flourished exceedingly, and Mr Rat became a great-great-great-grandpapa to ever so many minor Frisky Tails. These Frisky Tails finding the ancient quarter too much straightened for comfort, began to scratch further tunnels, and succeeded pretty well in opening additional honeycombs, till presently progress was stayed by a root of the tree. Now they had gnawed through and scratched away half a dozen other roots, and never paused to sniff more particularly at this than the others. But it so happened that this root was the one which supplied the green streak up the trunk of the tree with the golden sap of life drawn by mysterious chemical processes from the earth. Frisky Tails gnawed this root asunder, and cut off the supply of sap. The green streak up the trunk withered and died, and the last stay of the willow was gone. It only remained for the first savage south-wester of winter to finish the mischief. The south-wester came, and over went the trunk, crash across the brook. At first this was very awkward for the rats, as thereby most of their subterranean dwellings became torn up and exposed. But very soon a geological change occurred. The tree had fallen obliquely across the stream, and its ponderous head, or top, choked up the bed, or very nearly. The sand and small sticks, leaves, and so on, brought down by the current, filled up the crevices left by the tree, and a perfect dam was formed. Now, as stated before, the ground thereabout was nearly level, and so worthless in character that no man ever troubled his head about it. No one came to see the dam or remove it. The result was the brook overflowed, and then finding this level plateau, instead of eating out a new channel, it spread abroad, and formed first a good-sized puddle, then a pond, then something like a flood, and, as time went by, a marsh. This marsh extended over a space of ground fully a mile long, and altogether covered some nine hundred acres.