Page:Popular Science Monthly Volume 7.djvu/754

734 rows of trees have been inflected, and fields and portions of fields have changed places. Houses have also exchanged situations with each other.

4. It has been observed that clouds have become fixed or suspended over particular spots affected, or about to be affected, by earthquake, as in London, in 1749, in Calabria, in 1783; and it is more than probable that the fog that enveloped Euphemia, in Sicily, in 1638, Millitello in 1693, and other places when they were destroyed, arose from the operation of one cause.

5. Explosions of great violence frequently attend these convulsions, often with disastrous results. When Millitello was destroyed, there was a great explosion heard in the fog that enveloped it; traces were noticed afterward as of the presence of fire on the rocks in the neighborhood, and the vines in the country surrounding it appeared as though they had been seared by fire. A similar explosion was heard in 1783 at Castel Nuovo, in Calabria, when that place was overwhelmed.

6. A further peculiarity is the exemption of certain spots, although the shocks were felt in all the surrounding neighborhood. Thus, at Manchester, in 1777, St. Paul's Church and the Dissenting Chapel escaped. Both of these were low buildings without steeples, and the church situated over a common sewer; but other more lofty buildings, especially those with metal pipes attached, felt the shocks severely. At Blockley the shocks were experienced strongly at the church, but very slightly at the chapel about 300 yards distant, and the latter was constructed without water-pipes.

7. Earthquakes are very frequently attended by thunder and lightning. At Munster, in 1612, thunder and lightning were heavy during an earthquake; and in Sicily, in 1693, it caused very great mischief. This conjunction of lightning with earthquake was noticed by Luke Howard, and constitutes what he designates "spurious earthquake." One of the cases he mentions occuredoccurred [sic] in Radnorshire: "At Knill Court the oscillation of the house was plainly perceptible, and felt by all the family, and that, too, in several apartments, and was accompanied by a peculiar rumbling noise. At Harpton, a severe storm of thunder and lightning was experienced the same night and at the same time."

8. Peculiar rushing noises have also at times been perceived, as in Staffordshire in 1692, and London in 1749.

9. These convulsions are attended by the disturbance of the magnetic needle, and compasses on board ship are frequently for a time useless. On the 19th of January, 1845, on the Thames steamer, during an earthquake in the West Indies, they revolved on their pivots with great rapidity; and on the 29th of October, 1867, during a hurricane, there were shocks of earthquake at St. Thomas's, and the electrical disturbance was so great as temporarily to render the compasses unavailable.