146 FRAGMENTS OF SCIENCE. 



destiny of the Falls of Niagara. We may open our way to 

 this subject by a few preliminary remarks upon erosion. 

 Time and intensity are the main factors of geologic change, 

 and they are in a certain sense convertible. A feeble force 

 acting through long periods, and an intense force acting- 

 through short ones, may produce approximately the 

 same results. To Dr. Hooker I have been indebted for 

 some specimens of stones, the first examples of which were 

 picked up by Mr. Hack worth on the shores of LyelTs bay, 

 near Wellington, in New Zealand. They were described 

 by Mr. Travers in the " Transactions of the New Zealand 

 Institute." Unacquainted with their origin, you would 

 certainly ascribe their forms to human workmanship. 

 They resemble knives and spear-heads, being apparently 

 chiseled off into facets, with as much attention to 

 symmetry as if a tool, guided by human intelligence, 

 had passed over them. But no human instrument has 

 been brought to bear upon these stones. They have been 

 wrought into their present shape by the wind-blown sand 

 of Lyell's bay. Two winds are dominant here, and they 

 in succession urged the sand against opposite sides of the 

 stone; every little particle of sand chipped away its infini- 

 tesimal bit of stone, and in the end sculptured these sin- 

 gular forms.* 



The Sphinx of Egypt is nearly covered up by the sand 

 of the desert. The neck of the Sphinx is partly cut across. 



* "These stones, which have a strong resemblance to works of 

 human art, occur in great abundance, and of various sizes, from half- 

 an-inch to several inches in length. A large number were exhibited 

 showing the various forms, which are those of wedges, knives, 

 arrow-heads, etc., and all with sharp cutting edges. 



"Mr. Travers explained that, notwithstanding their artificial 

 appearance, these stones were formed by the cutting action of the 

 wind-driven sand, as it passed to and fro over an exposed boulder- 

 bank. He gave a minute account of the manner in which the varie- 

 ties of form are produced, and referred to the effect which the erosive 

 action thus indicated would have on railway and other works exe- 

 cuted on sandy tracts. 



"Dr. Hector stated that although, as a group, the specimens on 

 the table could not well be mistaken for artificial productions, still 

 the forms are so peculiar, and the edges, in a few of them, so per- 

 fect, that if they were discovered associated with human works, there 

 is no doubt that they would have been referred to the so-called 

 'stone period.'" Extracted from the Minutes of the Wellington 

 Philosophical Society, February 9, 1869. 



