56 



Mr. A. M. Worthington on the 



[Dec. 18, 



mingle, if too hard, drops are liable to rebound from their shallow 

 impressions, and to mingle with the neighbouring drops. 



If the tray of sand be placed at any considerable distance below the 

 starting point of the annulus, it will be found that the impression 

 made is a single small irregular pit with three or four lobe-like projec- 

 tions, showing that the annulus has contracted as it fell into a 

 single not perfectly symmetrical mass. 



This is the natural consequence of the excess of pressure on the out- 

 side circumference, which is no longer hindered by any friction, as in 

 the preceding experiments ; it is interesting to observe, that as the 

 depth of fall is diminished, the diameter of the whole impression 

 increases, while the number of separate drop-impressions likewise 

 increases, showing that the contraction continues, by reason of impetus, 

 after complete segmentation has taken place, and causes the re-fusion of 

 drops that have at one time been separate ; this re-fusion being 

 generally so conducted that the symmetrical arrangement of the drops 

 is tolerably well preserved. 



This will be seen from an inspection of the following tables of 

 observations, which are recorded without omissions. A few remarks 

 on the tables are necessary. It often happened that the annulus had 

 not remained circular, but had assumed a more or less elliptical form, 

 as shown by the impressions ; the tables contain the measures of the 

 greatest and least diameters in such cases, as well as their mean. 

 These measurements were made with a pair of compasses, and the 

 diameters mentioned joined what were judged to be the middle points 

 of the drop marks on either side of the centre ; the measures may be 

 taken as correct to 1 millim., but not beyond. 



In most cases the impressions were not equally distinct round the 

 whole of the circumference, but were most distinct and well divided 

 about one end of a diameter, and least so about the other end of the 

 same. When the mark was elliptical this diameter was generally the 

 shortest. 



Owing to the fact that each drop did not always remain in the hole 

 it had made in the sand, and that the partitions between neighbouring 

 drop-impressions were often cut through by the neck of liquid that 

 remains till segmentation is complete, it could not be positively 

 asserted in all cases (though it could in some) that the annulus had 

 split into such and such number of drops when it reached the sand at 

 any given depth, but rather that it consisted of a certain countable 

 number of distinct masses of mercury, some of which appeared to 

 consist of two, or in some cases, of three drops, still united by necks 

 of liquid, while the remaining majority consisted of a countable 

 number of separate apparently equal and regularly disposed drops. 

 Then there was in many cases a slight uncertainty as to the exact 

 number, to the extent of one drop more or less, and this could only be 



