1883. 131 Trans. N. Y. Ac. Set- 



tendency to fracture in any part." {The Am. Arch, and Build. News, 

 1882, p. 118). 



Also at the palace of the Alhambra, m Grenadn, Spain, one of the 

 two doors that have been christened " La Mezquita," exhibits an ancient 

 facing of three slabs of marble, the upper resting as a lintel upon the 

 two others, which form uprights, eleven feet in height, nine inches in 

 width, and only two and one-half inches in thickness. At eighteen and 

 one-half inches from the top of the door, the slab on the right begins 

 to curve and to detach itself from the wall, attaining the distance of 

 three inches at about three feet from the bottom. From a subsidence 

 of the material of the wall, an enormous thrust has been exerted upon 

 the right, and the marble, instead of breaking or of rupturing its casings, 

 has simply bent and curved as if it were wood. {La Nature, 1882.) 



I have also been informed at Sutherland Falls and other quarries 

 near Rutland, Vermont, that the bending of thin slabs of marble, 

 exposed to the sunshine in the open air and accidentally supported only 

 at the ends, has been there repeatedly observed. 



Fleurian de Bellevue discovered a dolomyte possessed of the same 

 property in the Val-Levantine, of Mt. St. Gothard. Dolomieu attri- 

 buted the property to " a state of desiccation which has lessened the 

 adherence of the molecules of the stone," and this was supposed to be 

 confirmed by experiments of De Bellevue, who, on heatmg inflexible 

 varieties of marble, found that they became flexible. 



This change, however, cannot be connected with the remarkably 

 small content of water existing in marbles, but with a peculiarity of 

 their texture, which has been briefly discussed by Archibald Geikie 

 (Proc. Roy. Soc. Edinb., 1S80), in an interesting investigation on the 

 decay of the stones used in Scotch cemeteries. He has pointed out 

 that the irregular and closely contiguous grains of calcite, which make 

 up a white marble, are united by no cement, and have apparently a 

 very feeble coherence. 



It appears to me probable also that their contiguous crystallization 

 has left them in a state of tension, on account of which the least force 

 applied, through pressure from without or of the unsupported weight 

 of the stone, or from internal expansion by heat or frost, produces a 

 separation of the interstitial planes in minute rifts. Such a condition 

 permits a play of the grains upon each other and considerable motion, 

 as illustrated in the commonly observed sharp foldings of strata of 

 granular limestones, without fractures or faults. In such cases, also, 

 I have observed that the mutual attrition of the grains has been 

 sometimes sufificient to convert their angular, often rhomboidal, orig- 

 inal contours into circular outlines, the interstices between the rounded 

 grains being evidently filled up by much smaller fragments and rubbed- 



