AMERICAN GEOLOGY EATONTAN ERA. 1820-1829. 283 



When the Philadelphia Academy of Sciences was established in 1812 

 he became its first president, holding- the office for five years, when 

 he was succeeded by William Maclure. Troost, with Owen. Maclure, 

 :ind others, joined the communistic society at New Harmony, Indiana, 

 in L825, but removed to Nashville, Tennessee, in 1827, and the fol- 

 lowing- year was elected professor of chemistry, geology, and miner- 

 alogy in the university of that city. In 1831 he became State geol- 

 ogist, holding the office till 1839, when it was abolished. Nine reports 

 were made during his time, but seven of which were published. Prior 

 to going to Tennesseee his most important geological work was a survey 

 of the region about Philadelphia, the same being done and the results 

 published in 1826 under the patronage of the Society for the Promo- 

 tion of Agriculture. 



The work comprised forty small octavo pages with a colored map 

 of the region included within a half circle north of the Delaware 

 River, having a radius extending a little beyond Chester, i. e., some 

 I7i miles. As may be readily supposed, fully three-fourths the area 

 was colored as- gneiss, with narrower bands extending in a general 

 way parallel with the river; in the northern part, of primitive clay- 

 slate and of limestone. Between the gneiss and clay-slate was a short, 

 narrow belt of serpentine, and between the clay-slate and limestone one 

 of eurite, and in the extreme northeastern portion of the sheet a band 

 of transition graywacke. Among the varieties of rocks mentioned, 

 in addition to those enumerated and comprising subordinate forma- 

 tions, are diabase and pegmatite. The eurite was described as occur- 

 ring north of the high ridge which separates the limestone from the 

 granitic rocks and as being in every respect similar to that of Penig, 

 on the Erzgebirge. "I was delighted, v he wrote, "at meeting this 

 rock for the first time on this side of the Atlantic. J imagined myself 

 transported to the Erzgebirge, in Saxony, and remembered with 

 renewed pleasure the father of geology, who made us acquainted with 

 it. 11 More than half of the paper was given up to a discussion of the 

 physical and chemical properties of the soil, as might be expected 

 when its date and the auspices under which the work was done are 

 taken into consideration. 



In the Boston Journal of Philosophy for the same year the ill-starred 



Prof. J. W. Webster gave a somewhat detailed account of the geology 



of Boston and vicinity, describing the three hills, to which "Boston 



owes its ancient name and so much of its picturesque 



Webster's Account . *■ 



of the Qeoiogy about beauty, as being" composed mainly of hard, compact 



Boston, 1826. J \ f i i n \ ■ , „•„ 



clay with gravel and bowlders. Amister s Hill was 

 described as composed largely of clay -slate, passing on the north into 

 hornblende slate, the latter containing veins of "greenstone;" and 

 Prospect Hill, in part of a greenish compact feldspar, which passes 

 into clay-slate, covered toward its northwest extremity by a mass 



