Corre'<poinl< n<'('. 01 
Hmitl hook of PJn/xicnl Gi'olot/i/. A. J. .riKKs-BjiouNK, London. George 
Bell and Sons, 12 mo., pp. 666, 1892. Second P^dition. This little 
volume cannot fail of being useful in the hands of all teachers and 
students of physical geology. It has little or no reference to histori- 
cal geology. Its grouping and presentation of the dynamics of the 
surface of the earth, its accurate definitions and its condensed sketch 
of recent progress in the sciences of mountain-making, metamorphism 
and the substructure of the crust of the earth commend it to such as 
desire a compend in convenient form and from a reliable authority. 
The whole of physical geology is discussed under three divisions, viz. : 
dynamical, structural and ijhysiograpliical geology. 
coreespo:ndence. 
The IlrctGixsvii.r.]-: Shkkt of tiik ^Mis.soriii Sritvicv. — I notice in 
your issue for this month a review of our publication entitled the 
"Higginsville Sheet in Lafayette Co./' in uhicii you raise certain 
objections to the form of publication, and offer certain suggestions 
concerning the publication of maps. As the suV)ject is one in which I 
am very much interested, I wish to take this opportunity to reply to 
your objections and suggestions and to explain in some detail my 
reasons for adopting the form of ])ublic!iti<)n represented by the 
Higginsville sheet. 
It is my intention that the following remarks shall apply to a 
general system of mapping of a state or nation ; not to special maps 
preiiared for special purposes or of special districts. The accompany- 
ing reports referred to are brief descriptive reports of the area mapped, 
such as I have termed "Area Reports" (the equivalent of the county 
reports which have been used); large volumesor monographs treating 
of certain subjects, such as I have termed "Subject IJeports," are not 
to be included under these remarks. 
As I understand it, the questions at issue are: 
1. What shall be the unit of area ? 
2. What shall be the size of sheet ? 
3. In what form shall the sheet be published ? 
So far as I can gather from your review, I conclude vliat your an- 
swers to these questions would be as follows : 
1. The county shall be the unit of area. 
2. The size of the sheet shall be uniform. I)ut siiall not exceed a 
large quarto ]»age in dimensions: that is, the maximum size shall 
be about 9x12 inches. 
3. The map shall be published as an insert in a cpiarto volume. 
My answers to these questions, on the contrary, are as follows : 
