FROM NEAR LAKE AINSLIE, N. S. POOLE. 341 



The pitting is fairly uniform and about of the size and 

 depth given to the depressions on the top of ladies' sewing 

 thimbles. An appearance somewhat similar may be produced 

 by stirring on a glass plate or other non-absorbent surface a 

 thick mud of proper consistency, and allowing it to dr\'. When 

 mud is rightly prepared and globules of air are incorporated in 

 the mass, tliere is left on evaporation a coating having a 

 pitted surface like that on this stone. To account then for this 

 pitting phenomenon we may assume that the final concentric 

 coating possessed such a consistency and the usual cementing 

 equalities. I may add that Mr. M. V. Grandin, of Cheticamp, 

 informs me he has seen the same external structure on fragments 

 of lava on the slopes of Vesuvius. 



On fracture these balls show an interior of irregular com- 

 po.sition sometimes with cavities, parts being granular and easily 

 pulverized and parts being like that of the outside coating, of 

 a fine homogeneous material. The cavities were not found 

 to contain crj'stals, but one was lightlj' bridged over by a 

 crust not a 32nd of an inch thick. The concretionary^ exterior 

 may be somewhat shelly, and shows that it has gathered 

 additions splashed on in drops or patches. These are easily 

 distinguishable by the slight irregularity of form thereby 

 produced, which is often enhanced b\' a variation in col ring. 

 That the accretions have been of varied degree of fluidity, is 

 made evident by the extent to which they have spread out 

 over the spherical surface, and their appearance would remind 

 one who has visited a pottery establishment, of the action of 

 ' slip' on the clay forms in the hands of the potter. 



Besides the deformation due to impact or pressure, it will 

 be seen they have suffered fracture under two distinct condi- 

 tions, one in common with rocks in genei-al from shrinkage in 

 some ordinary form, and the other exceptional and attributable 

 to sudden violence while in a non-homogeneous state such as 

 is possessed by man}' articles of domestic confectionary like 



