284 W A. Norton — Experiinents on Wood, Iron, and Steel bars. 



Wise, Russell, and Tazewell, as may be seen from the account 

 of these counties given by Professor Lesley, in his paper read 

 before the Am. Phil. Soc, April 21, 1871. Professor Lesley 

 shows that under the so-called " Sheep Rock" in Wise county, 

 ai)Out 700 feet of coal-bearing rocks are disclosed, with the base 

 not shown. The "Sheep Rock" is No. 21 of the Piney Ri^ 

 section. In this space two coal beds are to be seen ; one, a si 

 foot bed, lies at the very base of the hills, and the other, a t\^ 

 foot bed, is a short distance above it. A similar formation e 

 ists in Russell and Tazewell counties. These coals are not to be 

 confounded with the beds seen in Montgomery county, for the 

 latter are found in the Vespertine strata, and are of the same age 

 with those near the White Sulphur in Greenbrier county. The 

 basin, in which these conglomerate coals were formed, evidently 

 extended still farther east than the counties described in Professor 

 Lesley's paper, as the considerable development of this series 

 in them shows. But in the more easterly extension of the field, 

 the number of seams have diminished, especially in the upper 

 part. On New River in Raleigh county the most important 

 coals are found within 700 feet below the upper ledge. 



As we proceed northward, along the eastern outcrop of the 

 series, it has been more extensivelv affected by erosion, and has 

 been swept off from the greater part of Monroe and Greenbrier 

 counties, these being occupied mainly by the Umbral shales and 

 limestone. Professor Rogers mentions finding at the top of 

 Greenbrier Mountain, in the northeast part of the county of that 

 name, a massive sandstone resembling the conglomerate. This 

 is no doubt a remnant of the series. North of this point, in Rich 

 Mountain, in Randolph county, the entire series is presented, 

 capping the mountain, according to Dr. Stevenson. But here it 

 has undergone an important modification, from the loss of the 

 shaly central portion, and the almost entire disappearance of the 



[To be continued.] 



I the Set of bars of 



^ ^ .^._. .. _ : Stress; by Wm. A. 



Norton, Professor of Civil Engineering in Yale College. 



At intervals, during the last two years, I have carried on a 

 systematic series of experiments, with the view of determining 

 the laws of the set of materials resulting from a transverse 

 stress under varied circumstances. The experiments were 

 made with the testing machine which I devised several years 



, .^. the purpose of experimenting on the de 



bars under a transverse stress. A detailed description of this 



the deflection of 



