But upon a stricter Enquiry into the Matter, finding I had reason to suspect that few, if any, actually had tried the Experiment, I was minded to bring the Thing to the Test of Experiment my self; and having an Opportunity, on April 11. 1712. I caused divers Places to be bored, laying the several Strata by themselves; which afterwards I weighed with all Strictness, first in Air, then in Water, taking Care that no Air-bubbles, &c. might obstruct the Accuracy of the Experiment. The Result was, that in my Yard, the Strata were gradually specifically heavier and heavier, the lower and lower they went; and the upper which was Clay, was considerably specifically lighter than the lower Stratum; which was first a loose Sand, then a Gravel. In which Stratum principally the Springs run that supply my Well.
But in my Fields, where three Places were bored (to no great Depth) I found below the upper (superficial Stratum) a deep Bed of Sand only, which was of different Colours and Consistence, which I weighed as before, together with the Virgin-Mould; but they were all of the same, or nearly the same specifick Gravity, both out of the same Hole, and out of different Holes, although the Sand was at last so gravelly, that it hinder’d our boring any deeper.
Upon this, fearing lest some Error might be in the former Experiments, I try’d them over again; and that with the same Success.
After this, I made some Experiments in some deep Chalk-Pits, with the Flints, Chalk, &c. above and below; but the Success was not so uniform as before.
Acquainting our justly renowned R. S. with these Experiments, they ordered their Operator to experiment the Strata of a Coal-Pit; the Success whereof may be seen in Philos. Trans. Nr. 336.
CHAP. III.
Of the Subterraneous Caverns, and the Vulcano’s.
I shall take notice of the subterraneous Caverns, Grotto’s and Vulcano’s, because they are made an Objection[a] against the present Contrivance and Structure of the Globe. But, if well considered, they will be found to be wise Contrivances of the Creator, serving to great Uses of the Globe, and Ends of God’s Government. Besides many secret, grand Functions and Operations of Nature in the Bowels of the Earth, that in all Probability these Things may minister unto, they are of great Use to the Countries where they are[]. To instance in the very worst of the Things named, viz. the Vulcano’s and ignivomous Mountains; although they are some of the most terrible Shocks of the Globe, and dreadful Scourges of the sinful Inhabitants thereof, and may serve them as Emblems, and Presages of Hell it self; yet even these have their great Uses too, being as Spiracles or Tunnels[c] to the Countries where they are, to vent the Fire and Vapours that would make dismal Havock, and oftentimes actually do so, by dreadful Succussions and Convulsions of the Earth. Nay, if the Hypothesis of a central Fire and Waters be true, these Outlets seem to be of greatest Use to the Peace and Quiet of the terraqueous Globe, in venting the subterraneous Heat and Vapours; which, if pent up, would make dreadful and dangerous Commotions of the Earth and Waters.
It may be then accounted as a special Favour of the divine Providence, as is observed by the Author before praised[d], “That there are scarcely any Countries, that are much annoyed with Earthquakes, that have not one of these fiery Vents. And these, (saith he) are constantly all in Flames whenever any Earthquake happens, they disgorging that Fire, which whilst underneath, was the Cause of the Disaster. Indeed, (saith he,) were it not for these Diverticula, whereby it thus gaineth an Exit, ’twould rage in the Bowels of the Earth much more furiously, and make greater Havock than now it doth. So, that though those Countries, where there are such Vulcano’s, are usually more or less troubled with Earthquakes; yet, were these Vulcano’s wanting, they would be much more annoyed with them than now they are; yea, in all Probability to that Degree, as to render the Earth, for a vast Space around them, perfectly uninhabitable. In one word, (saith he) so beneficial are these to the Territories where they are, that there do not want Instances of some which have been rescued, and wholly delivered from Earthquakes by the breaking forth of a new Vulcano there; this continually discharging that Matter, which being till then barricaded up, and imprisoned in the Bowels of the Earth, was the occasion of very great and frequent Calamities”. Thus far that ingenious Author.