212, Proceedings of Indiana Academy of Science. 
Plate II was obtained by replacing the four short tubes with two 
longer tubes, of internal diameter .25 cm. and 1.15 cm. respectively, 
each 10 cm. long, and adjusted radially as in Plate I. Note that in 
this case the wave through the small tube is actually slightly in advance 
of the wave through the large tube, the distances on the original plate 
Plate II. 
being .89 cm. and .84 cm. respectively. The wave near the gap is the 
reflected wave from the side of the box which enclosed the gaps and 
dry plate. The percent increase in velocity in this case is obtained as 
before by dividing .89 by 16.5, the length of the tube shadow on the 
negative. This gives 5.4 percent, about half the value obtained with the 
shorter tubes, which were about one-fourth as long as the two shown on 
Plate II. The gain in distance traversed was 0.48 em. for the small 
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