No. 104.] 205 



heavier beds in the Portage group along the base of the Catskill 

 mountains. The stone has great strength and durability, wearing 

 very slowly when used for steps, and possessing the great merit of 

 retaining a certain degree of roughness of surface. The dark color 

 may be regarded as the only objectionable feature. 



In the central and western part of the State, the Portage sand- 

 stones are of a lighter color, usually moi*e friable than those of the 

 eastern outcrops. Many of the beds are of a greenish or olive-gray 

 color, occurring both in flaggy and heavier courses, which are easily 

 dressed and present a very good appearance. The frequent presence 

 of iron pyrites, causing both staining and disintegration, offers an 

 objection to their extensive use. In the western counties, however, 

 some of the beds are nearly gray, having lost the greenish or olive 

 color almost entirely, and at the same time have less argillaceous 

 matter in their composition, with scarcely a trace of iron pyrites. 

 The stone from these beds has a very uniform gray color, a fine 

 texture, and if quarried and dried before exposure to the frost, is a 

 very durable stone. 



In Ohio, the arenaceous beds of the Portage group furnish the 

 friable gray sandstone from which grindstones are largely manu- 

 factured, and from which more recently large quantities of building 

 stone have been furnished. The cohesion of the particles is slight, 

 and the stone is very brittle on first quarrying, but becomes stronger 

 and harder on exposure, and, if properly selected, resists the effects 

 of the atmosphere in a remarkable degree. The strong cohesion of 

 the particles, therefore, is not always a requirement for durability, 

 though it is for strength, either as resisting direct pressure or the 

 effect of tensile force. 



It should not be forgotten, however, that neither all the beds of 

 this stone, nor all parts of the same bed, are uniform in texture, 

 composition or durability, and it will not be surprising, if in its in- 

 discriminate use it may sometimes prove unsatisfactory as a building 

 stone. 



The argillaceous sandstones of the Chemung group are generally 

 or comparatively free from iron pyrites, and range in color from 

 gray to olive or dark olive-brown. When quarried and exposed to 

 drying before freezing, they are comparatively durable stone; but 

 they cannot be safely quarried during winter, or exposed to freezing 

 soon after quarrying. Building stones from this group, within the 

 State of New York, have long been used, and new quarries have 

 been opened at many points, though the stone has usually but a local 

 importance. The more important structures erected from this stone 

 are the buildings of the Cornell University at Ithaca. 



Manner of Laying. 



Sandstones or freestones, and all the varieties of argillaceous sand- 

 stones, should be laid in the building according to the natural bed- 

 ding of the rock, so that the we^r of the elements may act upon the 

 exposed edges of the laminae. Since it is impossible to have any great 



