226 THE POPULAR SCIENCE MONTHLY. 



from 12 feet to 20 feet, in consequence of the deposition of solid mat- 

 ter caused by the diminished motion of the river. 1 



In conclusion, we may say a word regarding the proximate future 

 of Niagara. At the date of excavation assigned to it by Sir Charles 

 Lyell, namely, a foot a year, five thousand years will carry the Horse- 

 shoe Fall far higher than Goat Island. As the gorge recedes, it will 

 drain, as it has hitherto done, the banks right and left of it, thus leav- 

 ing a nearly level terrace between Goat Island and the edge of the 

 gorge. Higher up it will totally drain the American branch of the 

 river, the channel of which in due time will become cultivable land. 

 The American Fall will then be transformed into a dry precipice, form- 

 ing a simple continuation of the cliffy boundary of the Niagara. At 

 the place occupied by the fall at this moment we shall have the gorge 

 enclosing a right angle, a second whirlpool being the consequence of 

 this. To those who visit Niagara five millenniums hence, I leave the 

 verification of this prediction ; for my own part, I have a profound 

 persuasion that it will prove literally true. 



-+++- 



STATE GEOLOGICAL SURVEYS. 



By Pkof. ALBERT E. LEEDS, 



OF THE STEVENS INSTITUTE OF TECHNOLOGY. 



A STRENUOUS effort is being made at the present time to reor- 

 ganize the Geological Survey of Pennsylvania. It promises to 

 be successful. The legislators of that State, in voting upon the measure, 

 will be mainly influenced by considerations relating to the pecuniary 

 value of a geological survey in locating beds of coal, building-mate- 

 rials, and ores. But the educated public will desire to know, in addi- 

 tion to these matters, what influence such a geological survey will 

 have upon the intellectual activity of the community at large, and how 

 great an amount of scientific bustle it will create in the museums and 

 laboratories of institutions of learning. 



A very satisfactory answer can be given to the first of these 

 queries, after reviewing the scientific periodicals and journals of 

 learned societies in this country, during the last half-century. It will 

 be seen that the desultory descriptions of plants, birds, and the ex- 

 ternal characters of minerals, which constituted a large portion of the 

 scientific literature at the beginning of this period, gave place to 

 laborious analyses, and to elaborate articles on geological phenomena. 

 Many of the most valuable contributions to science during this epoch 

 consisted in reports of the geological surveys then in progress, or in- 



1 Near the mouth of the gorge at Queenstown, the depth, according to the Admiralty 

 Chart, is 180 feet ; well within the gorge it is 132 feet. 



