Chemistry and Physics. 



By sliohtly raising or lowerinir the plank, or by its entire i 

 (In' rlame is once more agitated. In these experiments 

 pitched reed was used, so that it was easy to produce 

 motion of the plank the retardation of half a wave-length i 



In (ieneral l)uane"s ease, a fairly smooth sea would he 

 f"r the reflection ; while the position of the zone of silenc 

 he determined l»v the height <>| the signal on the one h; 

 the height of tin*, observer on the other above the surfaci 

 -•a. The position would also, of course, depend on the 

 the note of the whistle.— I\o<>. R»u. ti„c, xxxiv, 18. 



14. On the Reversal of the Metallic Lines in over 



holographed " 



Ah„e 



IImm" 

 In i 



v, Jan-.-nb In regard 



I obtained ..n one'oeea- 

 I endeavored to secure 



to this subject 



Proh 



ssor w. 



X. 



;.i„:!:;; 



middle distance, and' str 



»d, but the sui 



; ! i 



TlZul 



lark 



!''hK 



'wcame a W 1 !!;''i,il"e Ul \ h : 



"f ' Vh I-' m i- r'-dV^ 'l i'i 



L V V" 





■ivd 



