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SCmNGE. 



[N. S. Vol. IX. No. 216. 



the date of writing by sketches of tlie work of 

 all existing institutions which are contributing 

 to a knowledge of Maryland's resources. The 

 valuable work of the late Professor G. H. Wil- 

 liams is appropriately set forth at length. The 

 sketch closes with lists of the surveys and 

 maps relating to Maryland made by the U. 

 S. Coast and Geodetic Survey and the U. S. 

 Geological Survey, and these lists are sup- 

 plemented by excellent index maps of the 

 State, showing the triangulation and the ar- 

 rangement of map sheets. 



Following this historical article by Professor 

 Clark is a second, on the present knowledge of 

 the physical features of Maryland, embracing 

 an account of the physiography, geology and 

 mineral resources. Of this it need only be said 

 that it is concise, complete and accurate, so far 

 as the data now available permit. This report 

 frankly recognizes the existing information con- 

 cerning the State as the seed from which future 

 knowledge must grow. An excellent geologic 

 map lithographed by Hoen & Co. illustrates the 

 article. 



A bibliography and account of cartography of 

 Maryland, by Dr. B. B. Matthews, logically 

 completes the historical portion of the volume 

 and constitutes an important work of refer- 

 ence. 



An earnest of the important results which 

 the Maryland Survey is to accomplish is con- 

 tained in the article by L. A. Bauer on a mag- 

 netic survey of the State. Including an ac-. 

 count of the history and objects of magnetic 

 surveys, this preliminary report is of broad 

 general interest. Declination and dip of the 

 needle and intensity of the magnetic forces are 

 defined. A history of magnetic surveys and an 

 account of methods follow. There is an ex- 

 tended account of variations of magnetic decli- 

 nation. The distribution of the declination in 

 Maryland is described and illustrated by a map. 

 And, finally, the economic value of the work is 

 set forth in a discussion of the establishment of 

 surveyor's meridian lines. 



The second volume of the Maryland Survey 

 reports, when compared with the first, is a 

 demonstration of the wisdom of doing one thing 

 well and the next thing better. Both volumes 

 are superior in utility and appearance to any 



State report previously issued. That the Mary- 

 land Survey has already won the confidence of 

 the people and the Legislature is shown by the 

 appropriations of $5,000 to promote topographic 

 surveys and $10,000 to conduct investigations 

 for betterment in highways. These sums, added 

 to the appropriation of $10,000 for geology, 

 place in the hands of the Geological Survey 

 Commission annually $25,000 to be spent for 

 the benefit of the people of the State. That it 

 will be expended in securing authoritative in- 

 formation appears from the contents of the sec- 

 ond report. 



Dr. G. P. Merrill, an authority on building 

 stones, contributes an article on the physical, 

 chemical and economic properties of building 

 stones in general, with special reference to the 

 needs of the Maryland industry. This article 

 is of general interest, as furnishing information 

 of primary importance to capitalists, quarry- 

 men and users of stone. It is followed by an 

 exhaustive description by Dr. Mathews of the 

 quarry products of Maryland considered with 

 reference to their qualities, accessibility and 

 adaptation. The subject is treated in detail, be- 

 ing classified under the headings : ' Granites and 

 Gneisses,' ' Marbles and Limestones,' ' Sand- 

 stones,' ' Slate,' and the ' Building Stone 

 Trade,' and further subclassifled by localities 

 throughout the State. The author personally 

 examined each quarry and made his observa- 

 tions with expert knowledge. The report is 

 very beautifully illustrated, not only by the 

 usual photographs of quarries, but also by 

 photomicrographs of the rocks and by full-page 

 colored heliotypes which represent the texture 

 and color of the stone as they appear in a 

 smoothed specimen. 



The appropriation of large sums to prepare a 

 topographic map of Maryland atTords a reason 

 for stating the objects of such a map, and such 

 a statement might suffice simply as an explana- 

 tion. But to meet the educational purpose of 

 the Maryland Survey more is required, and 

 this something more is supplied by Mr. Gan- 

 nett' s article on the aims and methods of car- 

 tography with especial reference to topographic 

 maps. The methods now in use in extensive 

 surveys were developed by Mr. Gannett and 

 his assistants and are characteristically original. 



