400 GEOLOGY OF EASTERN WISCONSIN. 



The following species were collected at this point: Orthis im- 

 pressa, Strophodonta demissa, S. perplana, Sperifera medialis, S, 

 pinnata, Atrypa reticularis, Palceoneilo constricta, P. emarginata, 

 Modiomorpha concentrica, two new species of Gomphoceras, Pha- 

 cops rana, and several imperfect forms belonging to the genera 

 Cyathophyllum, Lingula, Spirifera, Palceoneilo, Modiomorpha and 

 Ecculio7nphalus, and the plate of a Placoderm fish. 



Economic Considerations. The credit of first calling attention to 

 the hydraulic properties possessed by the rock of this formation be- 

 longs to the late Dr. I. A. Lapham, who, some years since, directed 

 attention to it as probably possessing the property of hydraulicity. 

 In an article prepared for Walling's Atlas of Wisconsin, under date 

 of July, 1874, he called attention to the geological relation existing 

 between this rock and the water-limestone of Louisville, Ky., with a 

 suggestion as to its possessing the same useful qualities. The first 

 investigations upon the part of the geological survey were made by 

 the party under my charge, between the 5th and 12th of June, 1874, 

 and specimens were sent to the chemist of the survey for analysis on 

 the latter date, but owing to the crowded state of that department, 

 analyses were not received until the following year. The investiga- 

 tions of Dr. Wight upon the same subject in the year 1875 are fully 

 stated in his Annual Report. The credit of demonstrating by actual 

 tests, the unusual hydraulic excellence of the rock of this formation, 

 is due to the gentlemen constituting the Milwaukee Cement Co., and 

 to Mr. D. J. Whittemore, Chief Engineer of the C., M. & St. P. E. 

 H. To these gentlemen I am under obligations for the following 



CD O CJ 



facts, relating to their interesting and important investigations: 1 



The first series of experiments of Mr. Whittemore to determine 

 the quality of this rock as a cement stone, and the strength and value 

 of the product, extended continuously over nearly one year and a half, 

 and embraced about 1,500 individual tests, and perhaps an equal num- 

 ber has been made by him and other competent gentlemen since. 

 These experiments were conducted according to standard methods, 

 with excellent apparatus, and appear to have been characterized by 

 impartiality in selection, and conscientious care in manipulation. The 

 results obtained from the commercial cements with which comparison 

 was made compare very favorably with those obtained by other com- 

 petent experimenters upon the same products, which indicates that 

 the selection was a fair one, and as the several samples were subjected 

 to the same processes, the results possess much more value than if 



1 See a paper read before the Fortnightly Club of Milwaukee, November 4,1875, by 

 Don J. Whittemore, of which the following is little more than an abstract. 



