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262 parallelism and for their steady declining gradation of curvature when they are compared in any east and west section across the corrugated zone.’ To the westward of the Appalachian chain, where this structure is conspicuous, he pointed out that ‘the crust waves flatten out, recede from each other, and vanish into general horizontality.’ Coupled with these leading features he remarked that the total thickness of the coal measures steadily diminishes from some three thousand feet thick in Pennsylvania to fifteen hundred feet in the Illinois basin, and to not more than one thousand feet in the basins of Ohio and Missouri; and similarly the number of workable seams of coal diminishes from twenty-five on the Schuylkill to probably seven in Indiana and Illinois, and but three or four in Iowa and Missouri. And when we add to this the clearly established facts of the increasing amounts of sea deposits simultaneously with the decrease of land-derived materials eastward and the diminishing effects of metamorphoses in the same direction, from the fully bituminous coals of the Western States to the hard anthracites of the most disturbed region, it must be conceded that Prof. Rogers contributed a noble quota to the unraveling of some of the grandest phenomena which geologists have been called upon to investigate."

In the autumn of 1857 Prof. Rogers was appointed Regius Professor of Natural History in the University of Glasgow, which position he held until his death. A Glasgow paper thus describes his inaugural lecture:

"The hall was densely crowded and the lecture of the learned gentleman was listened to throughout with the most decorous attention, broken only at intervals when some passage of surpassing beauty evoked the spontaneous applause of the alumni. To great scientific attainments Prof. Rogers unites great popular ability. His intellectual faculties are admirably balanced. It would be difficult indeed to say whether the analytic or synthetic faculty is the stronger, so delicate is the poise of power. . . . It would be doing injustice to Prof. Rogers to attempt so much as an outline of the lecture delivered yesterday; suffice it to say that, as far as any lecture could be so, it was an exhaustive synopsis of the wide field of scientific research embraced under his professoriate. The grouping of the varied branches of the general subject was executed with the utmost precision and completeness. The marvels of Nature that were met at every turning in the path of investigation were brought most happily before the imagination of the neophytes of science, while the great practical results of the study of natural history were never once lost sight of, even in presence of its most gorgeous visions."

Prof. Rogers returned with his family to the United States on a visit in the summer of 1865. He went back to Scotland alone in