[Footnote D: The progress of discovery has shown, since this passage was written, that these gaps are not quite so considerable as I had supposed. The following paragraph, which appeared in July, 1843, in an Aberdeen paper, bears directly on the point, and is worthy of being preserved:-- "ARTESIAN WELL. "The greatest of these interesting works yet existing in Aberdeen has just been successfully completed at the tape-works of Messrs. Milne, Low, and Co., Woolmanhill. The bore is 8 inches in diameter, and 250 feet 9 inches deep. It required nearly eleven months' working to complete the excavation. "In its progress, the following strata were cut through in succession:-- 6 feet vegetable mould. 18 " gray or bluish clay. 20 " sand and shingle, enclosing rolled stones of various sizes. 6 " light blue clay. 3 " rough sand and shingle. 115 " Old Red Sandstone conglomerate, composed of red clay, quartz, mica, and rolled stones. 74 " alternating strata of compact, fine-grained Red Sandstone, varying in thickness from 1 to 7 feet, and clay, varying from 6 inches to 12 feet thick. 8 " 9 inches, mica-slate formation, the first two feet of which were chiefly a hard, brown quartzose substance, containing iron, manganese, and carbonate of lime. ----------- 250 feet, 9 inches. "The temperature of the water at the bottom of the well, when completed, was found to be within a fraction of 50° Fahrenheit, and the average temperature of the locality, deduced from twenty-three years' observation, by the late George limes, F. R. S., is 47° 1: hence, nearly 3 degrees of increase appear as the effects of central heat. The supply of water obtained is excellent in quality, and sufficient in quantity for all the purposes of the works. Such an opportunity of investigating the geology of the locality can but rarely occur; and, in the present instance, the proprietor and managers afforded every facility to scientific inquirers for conducting examinations. To make the bearings of the case clear and simple, the following is quoted from Mr. Miller's work on the Old Red Sandstone. [The writer here quotes the above passage, and then proceeds.] Mr. Miller will be glad to learn, that though the convulsions of nature have shattered the 'frame' along the shores of Aberdeenshire, yet the fragments are not lost, as will be seen from the section above described; they are here reposing _in situ_ under the accumulated debris of uncounted ages--chiefly the 'boulder clay,' and sedimentary deposits of the Dee and Don, during a period when they mingled their waters in the basin in which Aberdeen now stands. The primary rocks--the settings--our granites, of matchless beauty stand out in bold relief a mile or two westward from the sea-coast. Within this year or two, the 'Old Red' has been discovered at Devanha, Union Grove, Huntly Street, Glenburnie, Balgownie, and