1893.] NEW YORK ACADEMY OF SCIENCES. 77 



zoisite. If the limestone of tlie quarry could he traced to its 

 contacts with the surrounding rocks, an undertaking tbat is pre- 

 vented by the lack of outcrops, it is quite probable that it "would 

 prove to be an included piece caught up in an igneous mass, 

 and that thus its isolated character would find a reasonable 

 explanation. Professor Lesley surmises that the great develop- 

 ments of limestone in New Jersey may lie far below the surface 

 in Pennsylvania (Final Report, Vol. i, p. 111.) If this be true 

 the limestone may have become involved in the igneous rock 

 during the passage of the latter upward. 



Mr. G. K. Gilbert, of the U. S. Geological Survey, exhibited 

 photographs of a gaping fissure in the Aubrey limestone, 

 twenty-five miles north ol Canon Diablo Station, Atlantic and 

 Pacific Railroad, Arizona, and referred it to anticlinal rolls, as 

 there was no faulting. 



Prof. Kemp remarked on its interesting relations to many 

 mineral veins. 



Dr. Bolton read a letter from a representative of the Smith- 

 sonian Institute asking for information and analyses of mineral 

 spring waters. 



January 80, 1893. 



Stated Meeting. 



Vice-President Dn'. Bolton in the chair, about fifty persons 

 present. 



The minutes of December 19th were read and approved . 

 The following paper was then read, illustrated by experiments : 



FACT AND FALLACY IN THE BOO^IERANG PROBLEM. 



BY C. H. EMERSON, WHITEHALL, N. Y. 



I advance the statement, that — 



The Australian boomerang does not possess a single desirable 

 quality for an ideal boomerang flight, excepting only the gen- 

 eral consideration that it is made of wood, and has its centre of 

 gravity to one side of its main outline of figure . 



I refer only to the retui-ning boomerang, the principal 

 features of which, as stated by various authorities, are : In 

 general, the parabolic or hyperbolic curve ; in particular, the 



