POPULAR MISCELLANY. 



711 



and Prof. George H. Williams, of Baltimore, 

 vice-presidents ; and Prof. H. L. Fairchild, 

 of Rochester, N. Y., secretary. About sixty 

 papers were presented at this meeting, a few 

 of which are here briefly noticed : 



In his address as the retiring president, 

 Sir J. William Dawson, of Montreal, chose 

 for his subject Some Recent Discussions in 

 Geology, considering especially the building 

 up and development of the continents. He 

 noted the controversies respecting the age of 

 the older crystalline rocks, the true founda- 

 tion stones of continents, instancing those of 

 the Highlands of Scotland as described by 

 Geikie, and the older rocks of North America 

 as worked out by Logan and his successors. 

 He was inclined to think that the oldest 

 rocks that we shall know are the gneisses of 

 the lower Laurentian, and that these may be 

 regarded as the igneo-aqueous products of 

 the earliest action of the waters on the crust 

 of a cooling globe. He then referred to the 

 rival theories of mountain-building, and, 

 after distinguishing between mountains of 

 eruption (volcanoes), like Vesuvius and Co- 

 topaxi, mountains of slightly inclined strata, 

 like the Lebanon and the Sierra Nevada, and 

 mountains of contorted strata, like the Alps 

 and the Appalachians, noted the diverse 

 views as to the origin of the latter. He fa- 

 vored the time-honored contraction theory as 

 explained recently by Le Conte, but saw no 

 objection to connecting with this the depo- 

 sition theory of Hall and others, the ex- 

 pansion theory of Mellard Reade, and the 

 isostatic theory of Dutton. When it is neces- 

 sary to account for the compression of vast 

 masses of rock into a third of their normal 

 dimensions and for their elevation thousands 

 of feet above the level of the sea, we may 

 be thankful to invoke all available powers 

 each in its proper place, and the sculpturing 

 due to atmospheric agencies besides. 



Prof. C. H. Hitchcock, of Hanover, N. H., 

 spoke about Ancient Eruptive Rocks in the 

 White Mountains. He said that in his re- 

 ports of the New Hampshire Geological Sur- 

 vey he had described in detail a great va- 

 riety of granites occurring in the White 

 Mountains, without having discovered the 

 principle of their association. He then re- 

 viewed the order of these varied igneous rocks 

 and showed that the same structure found in 

 volcanoes appeared in the White Mountains. 



He was therefore convinced that the granites 

 were truly eruptive. If the modern view of 

 the formation of granite is correct, the depth 

 at which it is formed, as shown in the White 

 Mountain region, is from two thousand to five 

 thousand feet, and decidedly not forty thou- 

 sand feet, as some geologists have maintained. 



Prof. George H. Williams, of Johns Hop- 

 kins University, treated the subject of An- 

 cient Volcanic Rocks along the Eastern Bor- 

 der of North America. He proposed to 

 designate as volcanic only such igneous rocks 

 as had flowed up through vents to the sur- 

 face. All existing knowledge of the occur- 

 rence of these rocks during the early geo- 

 logic ages in eastern North America was 

 summarized, beginning with Newfoundland 

 and passing southwestward along the Appa- 

 lachian mountain belt. 



Mr. Alexander Agassiz, Director of the 

 Museum of Comparative Zoology at Harvard 

 LTniversity, presented An Account of an Ex- 

 pedition to the Bahamas, which were de- 

 scribed as formed of wave- worn and wind- 

 blown coral sands. 



Among the papers relating to the glacial 

 drift, Prof. T. C. Chamberlin and Mr. Frank 

 Leverett discussed Certain Features of the 

 Past Drainage Systems of the Upper Ohio 

 Basin, concluding that the lower portions of 

 the rock valleys of the upper Ohio and its 

 tributaries were eroded during an intergla- 

 cial epoch. Prof. G. Frederick Wright, de- 

 scribing parts of the same region in a paper 

 on the Glacial History of Western Pennsyl- 

 vania, referred the valley erosion in rock al- 

 most wholly to a preglacial time of higher 

 altitude of the country, citing the occurrence 

 of glacial gravel deposits extending from the 

 high terraces down to the bottom lands, and 

 regarding the Ice age as continuous and 

 geologically short. 



The Harvard Observatory. The begin- 

 ning of the Astronomical Observatory of 

 Harvard College is usually identified with the 

 appointment of Prof. W. C. Bond as observer 

 in 1840. The appearance of the first comet 

 of 1843 excited fresh interest in the subject, 

 and funds were collected to buy the great 

 telescope, which then had only one match in 

 the world, in 1 847. The resources of the ob- 

 servatory have since been increased by vari- 

 ous subscriptions, gifts, and bequests. The 



