104 Mr. G. F. Rodwell on some Effects 



when the water in A was level with the orifice of C, it dipped 

 *4 metre beneath the water-surface in A. The tube B was filled 

 with water before introducing it into A (the orifice C being 

 closed by the finger); on opening C, water flowed from A and 

 came to rest about 20 millims. above the orifice of C ; but when 

 a substance capable of being wetted by water was placed at C, 

 the water in A immediately sank to the level of C. The cause 

 of this is obvious : when the water in A had fallen nearly to the 

 level of C, the adhesion of the glass of B for the water within it 

 was sufficient to counterbalance the weight of a small column of 

 water in A ; but so soon as the water in B was allowed to come 

 in contact with another body outside B, the adhesion within 

 the tube was counterbalanced by adhesion outside, and water 

 consequently flowed from C until a perfect level had been estab- 

 lished. 



The tube D, 4*5 millims. in diameter, was placed above the 

 orifice C in such a manner that its centre was 6 millims. from the 

 centre of C, and it was caused to deliver a stream of water (flow- 

 ing from a cistern with a water-head of *66 metre) exactly at 

 a right angle to a line passing through the centre of C. The 

 apparatus being thus arranged, and the water in A standing on 

 a level with the orifice C, it is obvious that any force tending to 

 remove water from A has to overcome the downward pressure 

 of a column of water in the longer limb of B, and also that, the 

 greater the amount of water removed from A, the greater is the 

 pressure to be overcome. 



When water was allowed to flow from D at the rate of 1575 

 cub. centims. per minute, the following quantities of water were 

 removed from A by the lateral action of the stream : — - 



First half minute ... 21 cub. centims. 



Second „ ... 5*3 „ 



Third „ ... No water removed. 



The flow from D was now diminished one-half (viz. to 787*5 

 cub. centims. per minute), the level of the water in A with C 

 being first attained. The flow from A was as follows : — 



First half minute ... 5 cub. centims. 



Second „ ... *25 „ 



Third „ ... No water removed. 



When the flow of water from D was diminished to one-fourth 

 its original quantity (viz. to 393*75 cub. centims. per minute), 

 no water was removed from A. 



When water flowing fromD at the rate of 1575 cub. centims. 

 per minute was allowed to flow for half a minute (so that 21 

 cub. centims. were removed from A), and was then diminished 



