1884.] 



87 



this Anthracite atlas has been transmitted to the Society during the past 

 week, and it may be of interest to the members to know something of the 

 plan which has been adopted for the publication of these grand atlas 

 sheets. The direction of the publication of these atlases has been placed 

 under my charge. 



Since the commencement of the Survey, there have been numerous 

 sheets of geological maps and sections published to accompany the reports 

 of progress. These sheets have been printed on light paper and folded in 

 octavo atlases, or in a pocket of the reports. Anticipating a demand 

 which might arise for copies, upon heavier unfolded sheets from which 

 measurements could be made, of those maps and sections which were of 

 a more permanent character, an edition (1000 copies) of such maps and 

 sections has been printed on heavy atlas paper, the size of the sheets being 

 26 X 33 inches, except in one or two special cases. This size of sheet was 

 adopted on account of its being that upon which the maps and sections 

 could be most economically adjusted, and not as being a convenient one 

 for handling. 



The Grand Atlas has been divided into five divisions. Although all of 

 the sheets to be contained in any one of these five divisions are not as yet 

 printed, or even all constructed, it is proposed at the present time to issue, 

 in individual parts, the sheets of each division which have been printed ; 

 as other sheets shall be printed under the five divisions respectively, they 

 will constitute a second part of the same division. It is designed, however, 

 not to issue a separate part of a division until the sheets shall aggregate 

 twenty to twenty-five in number. 



Division I will contain the geological maps of the counties constructed 

 on a scale of two miles to one inch, 1-126, 720th of nature. In the notes 

 of explanation accompanying Part 1 of the county geological maps, con- 

 taining forty-nine sheets, covering fifty-six counties, which is now in press, 

 and which will shortly be issued. Prof. Lesley says: "None of these 

 county maps are correct, and it is a rare occurrence that any two or three 

 maps can be joined together to form one connected whole. The geology 

 of the counties has been outlined on the maps from outcrops, located with 

 reference to some topographical or geographical feature determined on the 

 ground, the position of which appears on the map. As a result of this 

 method, the geological outlines, at a line common to adjoining maps, do 

 not always meet, the geology on each being referred independently to the 

 topographical and geographical features of the two maps, which do not 

 themselves agree along the common line. In some cases adjustments have 

 been made, especially where the geology of several adjoining counties was 

 mapped by one assistant geologist. In cases where topographical maps 

 have been made by the Survey, the geology has been outlined on them, 

 and that portion of the county map containing such surveys has bcien made 

 to agree with them. Although it would be practically impossible to con- 

 struct an accurate geological map of the entire State from a compilation of 

 the county geological maps, yet it is apparent that when an accurate topo- 



