Page:Popular Science Monthly Volume 40.djvu/801

Rh suddenly disappeared, the sea rolling completely over the. place where it had stood. Then the whole of that portion of the town where the ship-channel had been sank at once into deep water, while the houses nearer the central rock sank, some up to the eaves, others up to the first floor, and others again one or two feet only, according to the distance at which they were situated from the water's edge. The shock of the earthquake, in fact, shook down the artificially sustained bank of sand; as the sand shook down and spread out, the houses subsided, while the sea, rushing in underneath as well as above, gushed up in spouts in the streets and completed the ruin. Fort Charles and the houses that stood on the rock foundation alone remained, and of these the greater number were terribly shattered. About sixteen hundred persons are said to have perished. The following sketches, showing roughly a section of Port Royal, before and after the earthquake, will help to explain what occurred.





The amount of damage done by an earthquake to buildings depends very largely upon the nature of the foundations, for the shock-waves of earthquakes travel at different rates of speed through different substances. As a rule it may be said that the more compact the substance the quicker the rate. Thus they travel fastest through solid rock and slowest through loose sand. The duration of the shock has everything to do with the amount of damage; consequently, in Port Royal, the sand gave way, and the houses built on it collapsed, while those built on the rock, though evidently shaken and thrown out of the perpendicular, remained standing.

We are able to append the following curious map, which is said to be an exact plan of Port Royal before the earthquake, and which shows what remained afterward. It must be observed, however, that the cathedral-church, which stood near the building known as King's House, is unaccountably omitted. The original is to be found in the library of the Institute of Jamaica, at Kingston. The dotted line shows the area of rock.