NUes.] 42 [May 7, 



hundred and seventy-five feet, and was about seventy feet back 

 from the working face, and parallel to it. About ten thousand 

 tons of rock were moved southward three- fourths of an inch. 

 The break extended perpendicularly through several sheets or 

 layers. The north end of the mass did not break from the pa- 

 rent rock. But few days or evenings passed that a fracture did 

 not occur and usually accompanied by reports. Within a few days, 

 while a north and south split of about one hundred feet in length 

 was being made in the old quarry, the stone suddenly freed itself, 

 and the liberated side moved northward five-eighths of an inch, the 

 south end still remaining fast. This liberated stone came in contact, 

 in its movement, with a projection, causing the crack to deflect to 

 the north-east and thirty feet beyond the wedges, breaking loose one 

 hundred tons of rock in addition to that split off by the wedges, 

 showing conclusively the north and south pressure. From the above 

 observations I note the following facts, viz. : — 



" In June the mass of ten thousand tons expanded southward down 

 the incline, the north or upper end remaining joined to the main 

 ledge. At the lower end the amount of movement was three-fourths 

 of an inch, but this movement gradually decreased in amount north- 

 ward till it was imperceptible at the upper end. 



" In November, a mass of three hundred tons expanded' north or 

 up the incline five-eighths of an inch, the south end being fast to the 

 parent rock. The same decrease in the amount of movement was 

 observed as in the break of June. 



" I notice, furthermore, that the deeper we go in the rock the 

 greater the amount of expansive movement." 



Dr. Brewer announced the donation of nine species of 

 birds from Chas. E. Aiken, Esq., and of the rare Micrathene 

 Whitneyi and Harporhynchus crissalis from Capt. Charles 

 Bendire. The thanks of the Society were voted to both 

 gentlemen for these valuable gifts. 



