246 



He also sent an account of some experiments on a new regis- 

 tering thermometer, in constructing which he prepared a bundle 

 of rods of iron and brass wire (No. 13), equivalent to 45.8 inches of 

 brass wire, antagonized by 45.8 inches of iron wire, on the prin- 

 ciple of the compensated pendulum ; these, connected with a series 

 of levers and a dial for inspection, and a registering point, moving 

 on parallel rods, actuated by clock-work, constitute the apparatus. 

 The rates of expansion of brass and iron, as ascertained by his 

 apparatus, do not agree with the rates given in the Reports of 

 the U. S. Coast Survey. This opens the way to the suspicion 

 that some of the " base lines " of the Coast Survey contain errors 

 larger than may heretofore have been looked for. He graduated 

 his dial according to the rates derived for the Reports, 93° for 

 the whole circle ; he found, in practice, that to agree with a mer- 

 curial thermometer his circle (dial) should read 120°. His com- 

 munication was referred to Prof Rogers to report upon. 



Prof. W. B. Rogers explained his views of the strati- 

 graphical relations of deposits formed in an ocean, under 

 each of the three conditions of a stationary^ a subsiding, 

 and a rising position of the sea-bottom, illustrating the 

 several results by drawings on the blackboard. 



In the first and second of the conditions here named, the level 

 of the resulting land would be approximately horizontal; while in 

 the third case, that of the uplifting of the ocean-floor during the 

 accumulation of the deposits, the surface would present a slope 

 descending from the oldest deposits on the first shore-line to the 

 strata latest formed ; in other words, the older deposits would crop 

 out at the higher level, and the successively later ones at a less 

 and less elevation. 



The Appalachian strata embraced between Lake Ontario and 

 the Pennsylvania coal region present a relation of levels the re- 

 verse of that last named, the older strata cropping out at succes- 

 sively lower levels as we proceed northward, while the newer 

 formations, the Devonian and Carboniferous rocks on the south, 

 are piled up to a height of some thousands of feet above the level 

 of these outcrops. For this and other reasons. Prof. Rogers could 

 not admit the theory which regarded the present stratigraphical 



