Page:Popular Science Monthly Volume 16.djvu/82

72 England, was invited, on account of his learning and character, to give an address, in which he made the following statements: "Wells Slink to a greater depth through stratified rocks often afford large supplies, but rarely rise to the surface; and in cases where they do so they are called artesian wells, from the circumstance of such artificial flowing wells being common in Artois (France). In all these cases [among which the Professor included the flowing wells at Grenelle, near Paris] the water was forced up by hydrostatic pressure to various distances from the surface. At Brentford, England, there were many wells that continually overflowed their orifice, which is a few feet only above the Thames. In the London wells the water rises to a less level than in those at Brentford."

By hydrostatic pressure, the Professor, of course, means a head, i. e., that the water flowed to these wells from a higher point. If this rise were due to hydrostatic pressure, why did the water rise to a lower level at London than at Brentford among the hills? Professor Buckland continues: "In November, 1840, notice was given of an application to Parliament to obtain a new supply of water for London from wells and water-works to be made at Wetford in the chalk-hills. A company had been proposed to effect this object, which would probably have been carried out, had not Mr. Clutterbuck demonstrated, by a long-continued series of measurements of the water in the chalk-hills of Hertfordshire, near Wetford, that every drop of water taken from that neighborhood would have been abstracted from the summer and autumn supplies of the river Coln and would have robbed the proprietors of more than thirty mills upon this river and its tributaries, and the owners of adjacent water-meadows, of rights they had had from time immemorial. One intelligent manufacturer, Mr. Dickinson, had, during many years, found arithmetical evidence that the quantity of summer water in the river Coln varied with the rain in the preceding winter. He could always tell, at the end of February or March, what water there would be in the following eight or nine months; and he regulated the contracts he made in every spring, for paper to be delivered in the summer and autumn, by the quantity of water in his winter rain-gauge. This rain-gauge, the invention of Dalton, being buried three feet below the surface, showed that except in December, January, and February, rain-water rarely descended more than three feet below the soil, so as to add anything to the supply that sinks into the earth to issue during summer, and from springs and rivers; and, whenever Mr. Dickinson found by this instrument that but little rain had fallen in the three months of winter, he proportionally limited his contracts for the following summer and autumn, thus proving the practical advantage of inductions from philosophy."

The following abstract from Professor Buckland's speech may also be in order: "As persons who have no experience in these subjects