STATE GEOLOGIST. 33 



ship of London, near Dundee. Mr. W. P. Christiancy also con- 

 tributed some instructive specimens. 



Thomas Crawford, Esq., of Detroit, has laid me under many 

 obligations for polished specimens of marble from his quarry 

 near Presque Isle ; as also for some unique fossils from the 

 same. 



Mr. M. B. Hess, of East Saginaw, has supplied some desirable 

 altitudes from the vicinity of Saginaw. 



Thomas Frazer, Esq., of the Mich. C. K. E. office, in Detroit, 

 has communiated the altitudes of the principal stations along 

 the line of that road. 



Superintendent W. K. Muir has furnished a list of altitudes 

 of all the stations along the Detroit and Milwaukie railway, ac- 

 companied by other valuable observations. 



Chief Engineer, John B. Frothingham, of Toledo, has also 

 promised to supply me with altitudes along the Michigan South- 

 ern Eailroad. It is hoped that such statistics will be further 

 communicated by Engineers, and others, to whom they are ac- 

 cessible. , 



I am indebted to the late John Farmer for a copy of the large 

 edition of his unequaled map of the State, and to Benjamin 

 Fowle, Esq., for a mounted map of Hillsdale county. 



Mr. John Holcroft, Superintendent of the Woodville Coal 

 Mine, furnished me with numerous data, and other facilities, 

 while investigating the coal formation of Jackson county. 



Mr. C. E. Hovey, Superintendent of the Eagle Plaster Co., of 

 Grand Eapids, provided me with a liberal quantity of samples 

 of the crude and manufactured gypsum, including some orna- 

 mental vases. 



Capt Maiden, keeper of the light house at Thunder Bay Isl- 

 and, furnished me with some interesting specimens from the 

 Huron Group. He is now engaged in a series of meteorological 

 and tidal observations of great importance. 



I am under obligations to very many of our citizens for ac- 

 companying me on my explorations, and conveying me to local- 



