22 Fictitious Vegetable Impressions in Sandstone Rocks. 



duced. This law is, that if a wire cut the magnetic curves, 

 a power is called into action that tends to excite in it an 

 electric current; and if a mass move across the same 

 curves, its parts being in different directions, and with vary- 

 ing angular velocities, there also are electric currents called 

 into evidence. 



Fictitious Vegetable Impressions in Sandstone Rocks. By 

 Lieut. R. Baird Smith, Bengal Engineers. 



An observation recently made on the effects produced by 

 very minute currents of water on the surface of newly depo- 

 sited beds of sand, has led me to conjecture, that possibly 

 some of those vegetable-like impressions so constantly found 

 in sandstone rocks, may owe their origin to the action of 

 similar causes, instead of being the casts of decayed organic 

 structures. The circumstances under which the observa- 

 tion alluded to was made, were these t to facilitate certain 

 repairs to a masonry dam across the Nowgong river, which 

 intersects the line of the Doab canal, about sixteen miles 

 to the northward of Saharanpore, a temporary " bund," or 

 breastwork of sand, protected from the action of the water 

 by means of piles and fascines of straw, was thrown across 

 the river. The water, however, percolating the sand in 

 minute streams, carried with it a considerable quantity of 

 fine sand, very similar in appearance to that, by the aggrega- 

 tion of which, the sandstone of the Siwalik Hills is formed, 

 and deposited it on the masonry flooring of the dam, to the 

 thickness of about an inch at the thickest part. On examin- 

 ing the surface of this deposit, I was much struck by the 

 vegetable-like appearance exhibited by the small channels 

 cut in it by the running streams, since they presented a per- 

 fect assemblage of the stems, main, and lateral branches of 

 shrubs. I annex a rough outline of a portion of the surface 



