VOL. XXVIII.] PHILOSOPHICAL TRANSACTIONS. 41 



planes in such an obliquity, yet it conforms in its figure to the asymptotes, viz. 

 ab the surface of the water, and ac the touching sides of the planes ; for sup- 

 posing the asymptote ac to be continued, as in the pricked line, till it surmounts 

 the surface of the water to such a height, or suppose the planes extended in 

 the same manner, then would the water remain between them in the appearance 

 of the pricked lines, being at all distances from the axis of the curve, equal in 

 respect to the asymptotes; and so of all the rest of the curves, which are the 

 result of the several angles, made by the touching sides of the planes. Now 

 when the touching sides were placed upwards, parallel to the surface of the 

 water, as in fig. 7> and plunged wholly under the same, then on lifting them 

 up, in the same position, till the weight of the water between the planes over- 

 balanced the power of their attraction, by this means a curve from each side of 

 the planes would open itself, and meet each other in the middle, as represented 

 in the aforesaid figure; where they would unite, and make a figure as joined 

 by the pricked lines, being wider in the middle than towards the sides of the 

 planes. And it is very remarkable, that this curve would always break out 

 between the planes, at an equal distance, between the touching sides and the 

 surface of the water. 



The same figure is likewise produced between two round glass planes, as in 

 fig. 8, the asymptotes being the same as the former ; that is, the one the sur- 

 face of the water, the other a tangent drawn from the touching point, parallel 

 to a tangent drawn from the open or opposite part of the planes, being at right 

 angles with a line drawn through the same. These experiments I find to answer 

 the same in vacuo, as in the open air ; so that that element has nothing to do 

 in this extraordinary appearance. 



The planes made use of in the foregoing experiments, were about 7 inches 

 square, opened on one side to an angle of about 20 degrees; the round planes 

 were near 3 inches in diameter. 



A further Account of the ascending of Drops of Spirit of fVine betiveen two 

 Glass Planes 10^ Inches long; with a Table of the Distances from the touch" 

 ing Ends, and the Angles of Elevation. By the late Mr, Fr. Hauksbee, 

 F.R.S. N*' 337, art. 14, p. 155. 



The spirit of wine did not move so nimbly between the planes, as oil of 

 oranges, which gave me the liberty to observe the angles with more delibera- 

 tion. The limb, on which the planes were laid, moved in the centre of a 

 quadrant of 4 feet radius ; the magnitude of which gave me the opportunity 

 of measuring the angles with greater accuracy : but the distance between the 

 drop on the planes, and the graduations on the quadrant, made it a little difficult 



VOL. VI. G 



