The vast amount of water circulating through the solid earth is shown by the calculations of the committee on the underground waters of the Permian and New Red sandstones.
Taking an average rainfall of 30 inches per annum, and granting that only 10 inches percolate into the rock, the supply of water stored up by the Permian and New Red formations was estimated by the committee to amount to 140,800,000 gallons per square mile per year. This rate would give, for the 10,000 square miles covered by the formations, in Great Britain, 1,408,000,000,000 gallons. Only a very small proportion of this amount is made available for the supply of cities and towns.
The subject of the chemical constitution of matter was taken up by Mr. Johnstone Stoney, F. R. S., who amused and interested the chemical section by a number of drawings of tetrahedra, octahedra, etc., on to which he dexterously stuck representations of oxygen atoms, chlorine atoms, and so on. His general endeavor seemed to be to convince his auditors that in most basic salts oxygen is divalent, being in direct combination with the acidifying constituent of the molecule, but that when oxygen is not so directly related to this constituent in basic salts it is tetravalent.
In the geological section, Dr. Bryce observed that there are two lines along which earthquakes are commonly observed in Scotland, the one running from Inverness, through the north of Ireland, to Galway bay, and the other passing east and west through Comrie. The phenomena of earthquakes in the latter district are now being systematically observed and recorded, under the direction of a committee appointed by the British Association, seismometers being employed on the two principles of vertical pendulum and delicately poised cylinders. Arrangements have been made to ascertain whether shocks in this region can be traced to any common central point, there being reason to believe them to be connected with a mass of granite in Glen Lednoch, whose position was indicated on a map exhibited by the author. He thought the Comrie earthquakes may be explained on Mr. Mallet's theory of a shock produced by the fall of huge masses of rock from the roof of huger caverns in the earth's crust.