GEOLOGICAL AND NATURAL HISTOEY SURVEYS. 453 



Ohio, unci New York borders. But in 1881, 1882, and 1883, Professor 

 White paid especial attention to the fossils of the middle belt of 

 counties on the Delaware, on the Susquehanna, and on the upper 

 Juniata Rivers, his results being embodied (without figures) in his 

 reports; Professor Stevenson did the same on the Maryland border; 

 and Professor Claypole was commissioned in the same three years 

 to prepare a special report of all the forms discoverable in the rich 

 district of the lower Juniata. A slight sketch of his results is given 

 in the preface and sufficiently full descriptions of the fossil horizons 

 in 'the text of his report F-2 on Perry County. Generic and specific 

 descriptions and figures have not been published. Enough has been 

 done, however, to make the published paleontology of New York 

 available in Pennsjdvania. 



The great want of the survey is a proj)er habitation, where its 

 large collections, now stored in the cellar of the Academy of Natural 

 Sciences, can be handled, discussed, and placed on exhibition for the 

 instruction of the public, and especially of the teachers of public 

 schools and academies during their summer vacations. In such a 

 building the models of surface relief and of underground structure 

 made by the survey, as well as the coiitoured and colored topo- 

 graphical and geological ma])s would be on permanent exhibition; 

 while many others might be added to the collection. 



Several of these models deserve mention, or are unique of their 

 kind. One exhibits the plicated structure of the southern anthra- 

 cite coal basin from the Little Schuylkill at Tamaqua to the Lehigh 

 River at Mauch Chunk. Another like it exposed to view the under- 

 grouiKi structure of the mammoth coal bed of the western middle 

 anthracite field, east and west of Mahanoy City. 



These models are not mere rough illustrations of the way in which 

 the coal measures of eastern Pennsylvania are folded, faidted, and 

 overturned, and of the kind of difficulties characterizing colliery 

 practice. They arc accurate exhibitions of the precise height, length, 

 breadth, and shape of the anticlinals and synclinal crimples which 

 together make up the coal basins studied l)y the surve}'. They were 

 constructed from parallel cross-sections through all the collieries, 

 on the same scale vertical and horizontal to avoid distortion; and 

 they carry the surveyed structure fi-om colliery to collierv, through 

 intervals of unworked ground sufficiently small to make important 

 errors practically impossible. Consequent!}^ the structure ahead of 

 the workings can be predicted with a fair approach to nicety; and 

 such measurements may be made to changes of dip, overturns, faults 

 and other troubles, as may advantageously modify the plans of 

 superintendents in advance. If the survey is continued every basin 

 of the anthracite region will be not only mapped but modeled in this 



