3 02 THE POPULAR SCIENCE MONTHLY. 



lated metallic wires or cables to a great distance with but little loss, 

 comparatively speaking, and could thus be made to run magneto-elec- 

 tric engines to do the work of steam in our mills and workshops, to 

 ignite electric lamps, etc. A copper rod, or cable, three inches in 

 diameter, says Dr. Siemens, would be capable of transmitting a thou- 

 sand horse-power to a distance of say thirty miles an amount suffi- 

 cient to give the light of a quarter million of candles, and suffice to 

 illuminate a town of moderate size. Two eminent American investi- 

 gators, Professors Houston and Thomson, of Philadelphia, having just 

 made an investigation with the especial purpose of determining the 

 practicability of transmitting the power of Niagara to great distances 

 by means of electricity, go even further than Dr. Siemens. They 

 make the astonishing assertion and, what is more, they prove it that 

 it would be possible, should it prove to be desirable, to convey the 

 whole power of Niagara to the distance of 500 miles or more by means 

 of a copper cable not exceeding a half inch in thickness. 



It is unnecessary for me to multiply examples upon this fruitful 

 theme of speculation, for the time admonishes me that I have already 

 trespassed sufficiently upon your attention, and I think I have con- 

 vinced you very fully that such queries as "What shall we do when our 

 coal-fields are exhausted ? need cause us no anxiety, for centuries be- 

 fore this possibility shall be realized, I opine, the world will no longer 

 stand in need of them. 



THE GEOLOGICAL SUEYEY OF THE FOETIETH 



PAEALLEL. 



Bt Professor J. S. NEWBERRY. 



THE geological survey of the country bordering the fortieth par- 

 allel of latitude was made under the direction of the War De- 

 partment by a party under Mr. Clarence King, who took the field in 

 1867. The area covered by the survey was a belt one hundred miles 

 wide, traversed by the Pacific Railroad between the Great Plains on 

 the east and the Sierra Nevada on the west, approximately between 

 the 104th and 120th meridians of longitude. The general object of 

 the survey was to connect the region of which the geological structure 

 has been made known through the California survey on the west with 

 the explored portion of the Mississippi Yalley, and thus to supply the 

 material for completing a section across the continent. In addition to 

 this it was proposed to determine by careful investigation the structure 

 and resources of the country lying adjacent to the Pacific Railroad, 

 which by the construction of this great work was opened to occupa- 

 tion, and was already invaded by a population eager to seize and de- 

 velop its hidden stores of mineral wealth. 



