Agreeable to our fifth position, Mr. Flamsted writes, "A hollow noise in the air always precedes an earthquake, so near that it rather seems to accompany them. He refers us to Philosophical Transactions No 151. p. 311. The noise was heard by many that liv'd in the out-streets, and alleys of London, remote from the noise and tumult of the greater streets,"
This he speaks of that felt in London 1692; but now the whole city heard the noise, on both these earthquakes of ours.
The gardener, who gave a relation to the Royal Society of what he observed in the Temple-garden, took notice, that first he heard the most dreadful noise imaginable, which he thought to be a great discharge of ship-guns, on the river: and that the noise rolled from the water-side towards Temple-bar, rather before the nodding of the houses.
The gentleman who observed it about Hartingfordbury, says, the noise preceded the shock. And this is a common observation, which at once both strengthens our opinion of electricity, and confutes that of subterraneous vapours; for, in the latter case, the concussion must precede the noise.
Agreeable to our second position, Mr. Flamsted writes, "That earthquakes are felt at sea, equally as on land. Our merchants say, that, tho' the water in the bay of