On AttraBion and Repulfion. * 119 



" momenta above and below this point." Now 

 gravitation, which is the obftacle to the above- 

 mentioned vibrating cylinder, ads upon its axisj 

 and becaufe the lower half has more volocity 

 which is not counterbalanced by quantity of 

 matter above, a waving motion is produced. 

 The reafon that the upper furface remains pa- 

 rallel to the top of the glafs is, becaufe a body 

 revolving about a center has a tendency to recede 

 from that center, fo that a glafs may be revolved 

 in a plane perpendicular to the horizon without 

 lofing any of the water. And unlefs the waving 

 motion when the glafs is vibrated be very vio- 

 lent, it cannot overcome the difference of fpc- 

 cific weight fo as to caufe an undulation of the 

 upper furface, as appears by the experiment of 

 quickfilver and water, where the weight of the 

 quickfilver, compared with water, renders its 

 waving motion on the furface as imperceptible 

 as that of the water or oil, having air only in 

 the upper part of the glafs. 



Drops of water rolling over the leaves of 

 colewort are prevented from adhering to the 

 furface by a blue powder, which covers the 

 leaves of that and various other plants, for if the 

 powder be wiped off the water will adhere. The 

 leaves of honey-fuckles and barbery frees are 

 blue on one fide only, and the water adheres" to 

 the green fide and not to the blue. If the fur- 

 I 4 face 



