“But their efforts were not of long duration. The tornado forced its way in the rear of the upper stories of my building, and with impetuosity unequaled forged through the apartments against the front wall. This wall popped out and fell to the pavement below, upon those standing there, burying them in the debris. The front is entirely gone, as you see. Mr. Harlow and the little boy Carl Rice, were close up to the front door, and only a small portion of the wall struck them. Taylor and the negro were out on the pavement further, and they fared worse. Taylor’s leg was broken at the ankle, and he was internally injured. The negro had a hole knocked in his skull larger than a silver dollar, and was used up generally. Mr. Harlow was bruised, but fortunately has no bones broken, and is not dangerously hurt. The little boy’s head was pretty badly cut and bruised, but he is not in a serious condition.” Now, in all of these cases is noticeable the same peculiar feature of walls falling outward, sometimes even against the wind: or of holes being burst in walls, the bricks being [Illustration: CORNER JEFFERSON AND TWELFTH STREETS, LOUISVILLE.] thrown so far that they could not be found, or distinguished from those of other houses. This might seem inexplicable--that the windward walls often fall outward. But it must be remembered that all storms with a wind system blowing spirally upward and inward are characterized by low barometer, signifying a diminution in atmospheric pressure at the storm center; and the lower the barometer, the more violent the storm. Now, it is clear that if a storm advance slowly, and be widely diffused, the air in the regions through which it moves has time to accommodate itself gradually to the change, and expanding slowly to equalize the pressure in all directions, its rarefaction is not perceptible to the ordinary observer: and the denser air within a dwelling expands so gradually that all the surplus can escape through chinks and crevices, if the doors and windows be closed. But the narrow-path tornado comes so rapidly as to produce little atmospheric change beforehand; while directly at its center the barometer may stand as much as two inches lower than in the surrounding region. Now, a fall of two inches means, in round numbers, a lessening of pressure of one pound to every square inch, or one hundred and forty-four pounds to the square foot. As the air normally presses equally in all directions, the passage of a storm of this sort may mean a sudden change from fifteen pounds pressure to the inch on each side of a wall, to fifteen pounds on the inside and fourteen only on the outside. When such a sudden change is brought to bear on every square inch of the interior of a house, it necessarily amounts to an explosion.