of the wave here therefore, as deduced from three independent sources, all corroborating each other, must be close to 13 feet per second.
A chimney hood of brickwork standing over the charcoal hearths in this kitchen, was at the end wall of nine inch brickwork , (Fig. 185, Sketch Coll. Roy. Soc.) started out from the same line of wall, by about 212 inches at top, in a height of 12 feet, but was not overthrown. It was propped however, by the return portion of the hood, at right angles to it, and so cannot be adopted for calculation, although affording a rude measure, that the velocity must have been small. In this same kitchen, the naked oak planking, of the ceiling or floor above, brown with wood smoke, shows where the ends of the boards have been drawn from their insertions in the walls, in the direction of their own length, and therefore transverse to the north and south joists, upon which they were laid, but which have not been moved, but to which the planks were not spiked or trenailed. The mark of the white mortar, shows the draw or shove to have been from north to south; it is 234 inches at the west end, and 4 inches at the east end, of the east and west wall, in a length of 25 feet; and as the normal to this wall bears 10° E. of north, the horizontal direction of wave-path deducible from this is as before, about 165° W. of north.
The actual amplitude of the wave in an horizontal direction cannot have greatly exceeded the average amount of shove, of these heavy beton and plank floors, and hence cannot have much exceeded 3 or 4 inches here.
In another room stands in a corner, against the wall , which ranges north and south 10° E., and abutting upon the wall at its southern end, a very heavy oaken household
