THE SPLASH OF A DROP AND ALLIED PNENOMENA. 207 



dropped from a height of 2 feet into water, gave the figures of Series 

 VI (Plate VIII), ill which it is seen that the water spreads over the 

 sphere so rapidly that it is sheathed with the liquid even before it has 

 passed below the general level of the surface. The splash is insignifi- 

 cantly small and of very short duration. If the drying and polishing 

 he not so perfect, the configurations of Series YII (Plate VIII) are pro- 

 duced; while if the sphere be roughened with sandpaper, or left wet, 

 Series VlII (Plate VIII) is obtained, in which it will be perceived that, 

 as was the case with a liquid drop, the water is driven away laterally, 

 forming the ribbed basket- shaped hollow, which, however, is now 

 prolonged to a great depth, the drop being followed by a cone of air, 

 while the water seems to find great difficulty in wetting the surface 

 completely. Part of this column of air was carried down at least 10 

 inches, and then only detached when the sphere struck the bottom of 



the vessel. 



Figs. 6 and 7 show the crater falling in, but this did not always hap- 

 pen, for the walls often closed over the hollow exactly as in figs. 4 and 

 5 of Series IV. Meanwhile the long and nearly cylindrical portion 

 below breaks up into bubbles which rise quickly to the surface. 



By increasing the fall to 5 feet we obtain the figures of Series IX 

 (Plate IX). The tube of fig. 1 corresponds to the dome of Series IV 

 and V, and is not only elevated to a surprising height, but is also in the 

 act of cleaving (the outline being approximately that of the unduloid 

 of M. Plateau). Figs. 2 and 3 show the bubble formed by the closing 

 up of this tube, weighed down in the center as in figs. 5 and of Series 

 V. Similar results were obtained with other liquids, such as petroleum 

 and alcohol. 



It IS easy to show m a very striking manner the paramount influence 

 of the condition of the solid surface. I have here a number of similar 

 marbles. This set has been well polished by rubbing with wash leather. 

 I drop them one by one through a space of about 1 foot into this deep, 

 wide, cylindrical glass vessel, lighted up by a lamp placed behind it. 

 You see each marble enters noiselessly and with hardly a visible trace 

 of splash. Now I pick them out and drop them in again (or to save 

 trouble, I drop in these other wet ones); everything is changed. You 

 see how the air is carried to the very bottom of the vessel, and you 

 hear the " ^;..*7rT;?o?" of the bubbles as they rise to the surface and burst. 

 These dry but rough marbles behave in much the same way. 



Such are the main features of the natural history of splashes, as I 

 made it out between thirteen and eighteen years ago. Before passing 

 on to the photographs that I have since obtained, I desire to add a few 

 words of comment. I have not till now alluded to any imperfections 

 in the timing apparatus. But no apparatus of the kind can be abso- 

 lutely perfect, and, as a matter of fact, when everything is adjusted so 

 as to display a particular stage, it will happen that in a succession of 

 pbservations tbere is a certain variation iix what is seen. Thus the 



