JIO 



THE POPULAR SCIENCE MONTHLY. 



concrete floor, in the green or wet state, of 

 a room say twelve and a half by twenty- 

 five feet, may be struck in a week after the 

 completion of the floor, if the concrete be 

 only six inches in uniform thickness, and 

 gauged in such proportions that every cubic 

 yard when in situ contains four bushels of 

 Portland cement, and six bushels of clean, 

 sharp, siliceous sand. One month after the 

 concrete has set, the floor would be ca- 

 pable of sustaining an equally-distributed 

 load of 112 pounds to the foot super- 

 ficial, and, twelve months after, an equally- 

 distributed load of 450 pounds per foot su- 

 perficial. If the thickness of the flooring 

 be increased to twelve inches, and the con- 

 crete gauged as before, a room nineteen and 

 a half feet in width by any length may be 

 covered with the same results as to strength, 

 as those given above for the room twelve 

 and a half feet in width. A wall of con- 

 crete is impervious to water, and fire-proof. 



A Relic of the lion mi-Builders. Through 

 the kindness of Prof. A. E. Dolbear, of Tufts 

 College, Massachusetts, I am enabled to pre- 

 sent to the attention of archaeologists a brief 

 notice and figure of an unusually interesting 

 specimen of carving in stone, the work of the 



mound-builders of Ohio. The history of the 

 specimen, as given me by Prof. Dolbear, is 

 briefly this : " It was ploughed up in a field 

 a few miles from Marysville, Union County, 

 Ohio." 



The relic is a small pebble of bluish- 

 gray slate, highly polished, and ground to 

 a moderately sharp edge. The front or 

 carved side is oval and of a uniform sur- 



face ; the back is sloped from a central flat 

 oval space, about one-fourth of an inch in its 

 long diameter. Had the specimen not the 

 carving of a face upon it, it could properly 

 be classed with that form of implement 

 known as the " celt," although these very 

 seldom have an edge extending along the 

 entire margin. Circular celts or " skinning- 

 knives," of about the same size, with a cut- 

 ting-edge along the whole margin, have been 

 found by the writer, in New Jersey. 



The remarkable feature of the relic 

 here described is the human face carved 

 upon one side. As a representation of a 

 woman's face, it is certainly artistically exe- 

 cuted. As has been remarked of a mound- 

 builder's smoking-pipe, having a somewhat 

 similar carving, 1 " the muscles of the face 

 are faithfully rendered, and the forehead is 

 finely moulded. The eyes are prominent 

 and the chin open, and full and rounded." 

 The nose and mouth are distinctly cut, but 

 not as accurately finished as the other 

 features. 



Although the labor expended upon the 

 stone to bring it to so well defined an edge, 

 about its margins, was so considerable, the 

 specimen can scarcely be considered an or- 

 namented cutting-implement. Celts, such 

 as we have referred to, are 

 never marked by carvings, 

 even of plain lines, so far 

 as we have collected them 

 in New Jersey ; although 

 some other forms, as plum- 

 mets (?) and pestles, were 

 occasionally carved. What, 

 indeed, this relic really was, 

 when the aborigine who 

 carved it had it in posses- 

 sion, it is useless to- conjec- 

 ture. Its value now con- 

 sists in its being a well- 

 preserved specimen of the 

 work of a stone-age savage ; 

 and possibly a characteris- 

 tic delineation of the features of a woman 

 of the race known as the mound-builders. 

 Charles C. Abbott, M. D. 



The Loan Exhibition in London. The 



exhibition of scientific instruments at Lon- 

 don was opened with an address by Mr. W. 



i " Flint Chips," p. 433, American edition. 



