SKETCH OF GERARD TROOST. 263 



Of the report made in 1849 the American Journal of Science 

 and Arts said : " The geographical survey of Tennessee, under 

 Dr. Troost, is still in progress, and is bringing to light many 

 additions to science, besides developing the various resources of 

 the State. Prof. Troost is well known for his learning, his skill, 

 and his enthusiasm in his investigation, and it is greatly to the 

 honor of Tennessee that such a savant is appreciated and his 

 talents are called into action. In a recent communication from 

 Dr. Troost he mentions that the number of the new genera and 

 species of Crinoidece, which occur in the State of Tennessee 

 is really surprising. His geological report, now before the 

 Legislature of the State of Tennessee, contains a monograph 

 of Crinoidece, in that State, in which sixteen new genera and 

 eighty-eight new species are described, illustrated by two hun- 

 dred and twenty figures; this number not only surpasses that 

 of those discovered in the other States of the Union, but per- 

 haps is equal to those that have been found over the whole of 

 Europe." 



Besides his geological reports of Tennessee, Dr. Troost con- 

 tributed to the Philadelphia Society for Promoting Agriculture, 

 A Geological Survey of the Environs of Philadelphia, the terri- 

 tory included in which embraced a semicircular area having a 

 radius of fifteen miles from the center at the Rotunda in High 

 Street, and bounded on the east by the Delaware River. A pre- 

 liminary note described the paper as " an attempt to delineate the 

 geological positions of our environs, and to give some general 

 ideas of the nature and chemical constituents of our soil." Of 

 the pamphlet of forty pages, containing a colored map, ten pages 

 were devoted to the geological survey, fifteen pages to descriptions 

 of soils, and ten pages to their composition. Prof. Troost also 

 published in the Transactions of the Geological Society of Penn- 

 sylvania an account of the organic remains and various fossils of 

 Tennessee and adjacent States ; in the Bulletin of the Geological 

 Society of France, a memoir on the organic remains and fossils of 

 Tennessee ; and in Silliman's American Journal of Science and 

 the Arts, articles on Amber at Cape Sable, Maryland ; Minerals 

 of Missouri ; Coral Regions of Tennessee ; Analysis of a Meteor- 

 ite from Tennessee ; Meteoric Iron from Tennessee and Alabama ; 

 A Shower of Red Matter in Tennessee ; Three Varieties of Me- 

 teoric Iron ; Meteoric Iron of Murf reesboro', Tenn. ; and Krausite 

 and Cacorene in Tennessee. He translated Humboldt's Aspects 

 of Nature into Dutch. He gathered a collection of about fif- 

 teen thousand mineralogical and more than five thousand geologi- 

 cal specimens, constituting what was at the time considered the 

 finest cabinet belonging to a single person in the United States. 

 Besides the Philadelphia Academy, he was a member of the 



