Vill PREFACE. 
cordial fulfillment of this promise, and more, on his part, the volume would lack 
much of its present value. His chapter on Iron Manufacture in Ohio will be recog- 
nized as the most important paper yet published upon this subject. 
There is no person in the State so well acquainted with the various systems of 
mining in force in Ohio as Hon. Andrew Roy, late State Inspector of Mines. The 
chapter which he has prepared on this subject will be found replete with valuable 
information. 
I am indebted to E. McMillin, Esq., Superintendent of the Columbus Gas Works, 
for a chapter giving all available facts on the production of gas from Ohio coals. Mr. 
MeMillin is widely known as one of our best trained’and most successful managers 
of gas-works, and his contribution is one of real scientific and practical value in this 
field. 
Professor G. Frederick Wright, of Oberlin, contributes an interesting chapter, 
accompanied by a map, upon the Glacial Boundary in Ohio. The author is recog- 
nized as one of our most accomplished glacialists, and his services have been brought 
into requisition in the Geological Surveys of the United States and of Pennsylvania, 
as well asin Ohio. If any question is raised as to the connection of this subject 
with economic geology, such question will be found answered in the chapter itself, 
in which the relations between soils, brick-clays, gravel-beds and water-supply with 
the glacial deposits are clearly shown. 
For the balance of the work, both in field and office, I have been obliged to rely, 
in addition to my own labors, mainly upon young men with little or no previous 
practical training, inasmuch as the services of such could be obtained at much lower 
rates of compensation than experienced geologists would demand, and inasmuch as 
the limited funds at my disposal required economy at every step. Asa matter of 
fact most of them were students or recent graduates of the State University who had 
studied geology in my own class-room, and who were consequently acquainted with 
my methods and views. All of them proved faithful and efficient, and several have 
acquired experience enough to fit them for independent work in our coal fields. 
Their names are as follows : 
J. N. Braprorp, Mech. Eng., FREDERICK Kerrsr, E. M., 
C. Newton Brown, Exits Lovesoy, 
Epwarp ©. Downerp, EpwarpD Orton, Jr., E. M., 
JoHn J. Dun, E. M., FREDERICK W. Spsrr, E. M., 
To this list the name of Prof. Anpert A. Wricurt, of Oberlin, is to be added. 
Mr. Brown was longer in service than any other, and the Survey is much in- 
debted to his faithful and discerning work. The chapter on the Meigs Creek coal and 
the map accompanying it (map No. 9) are entirely of his authorship. This is the 
only field which has been reported upon with which I am not personally familiar. 
To Mr. Brown is owing the demonstration of the identity of the Nelsonville and 
Carbondale coals. 
To Mr. Sperr, the credit belongs of working out the true place of the Steuben- 
ville Shaft coal, one of the best pieces of stratigraphical work recorded in the volume. 
Edward Orton, Jr., has prepared two chapters of the volume, viz., the chapter 
on Clays, and that on the Coal Mines of Coshocton county. : 
Prof. Wright made a careful and discriminating study of Holmes county, and 
has recorded his work in the chapter that treats of its coal seams. 
