Onr.p.nary regard to the experiments. 



Attraction by a quadnuit marked on paper, of near 20 inches ra 

 and the dius, diided into degrees and quarters. 



HYDRODYNAMICS. 



The angles were measured stations between the plates. 



467 



The following tables con. OnCapilUrj 

 tain the results for inclination of 10' and 18' : 





Taf 

 IWi npe- 



In the year 1712, Dr Brook Taylor communicated 

 to the Royal Society the beautiful experiment (See CA- 

 PILLARY ATTKAC i MS, vol. v. p. 409, *nd Plate CCX. 

 Fig. 6-) respecting the hyperbolic surface of water ele- 

 vated between two glass planes, inclined at an angle of 



Hart.be*'. 24 degrees. Mr Hawk.bee (Phil. Tram. 1712, vol. 



experiment xxv ii. p. 539. ) repeated the experiment with great care 



on the hjr. a t two different inclination*, of 20' and 40', and obtain. 



t**sL't (d the following result* : 



Angle ofW. 



DMaacw from Heights of the 

 the touching Water at the 

 i of the 



1 

 I 



i 



Angle 0/40'. 



Heights of Ihe 

 the tooekloff Water at the 

 > of Ib* preceding 



Plane*. 



6 



6 



74 

 10 

 12 

 15 

 19 

 28 

 50 



Mr Hawksbee afterwards found that the curve was 

 an exact hyperbola in all direction* of the plane*, the 

 axymptotes being the surface of the water, and a line 

 . . drawn along the touching sides of the planes. Mr 

 ^i Hawksbee's next experiments were made on the 

 fjit^, height* to which spirit of wine ascended between two 

 pi- plate* of gUs* separated successively to different dis- 

 tances. The following results were obtained : 



niiUncc of Plates. Height of Acent- 



0.0625 of an inch 0.166 of an inch 



0.03125 0.333 



0.015625 0.066 



0.007802 1.333 



Asa drop of spirits of wine when placed between 

 the two glass plane*, did not move so nimbly a* a drop 

 of oil nt' orange*. Mr Hnwkibee was enabled to observe 

 the angle* at which it remained suspended at different 



The preceding experiments of our author are not only 

 the most numerous but the moat correct that have been 

 made on capillary attraction, and have been appealed 

 to by La Place a* a proof of the accuracy of hi* own 

 theory. The opinions of Hawksbee respecting the 

 cause of capillary attraction were equally correct He 

 ascribed the ascent of the fluid to the attraction of the 

 whole surface of the tube ; and he considered the at- 

 tractive force of the glass as extending, like the refract- 

 ing force, only to insensible distance*. 



In the year 1718, Dr James Jurin communicated to Obema. 

 the Royal Society his Inanity into Ike Catue of the At- *" <* Ot 

 cent and Sutpention of Water in Capillary Tibet. This J * 

 paper contains many new and ingenious experiments ; 

 but its author was unfortunate in the erroneous expla- 

 nation which he give* of the phenomena. " Since in 



containing the suspended water in every tube, is always 

 a given quantity ; but the column of water suspended 

 U a* the diameter of the tube, therefore if the attrac- 

 tion of the containing surface be the cause of the water's 

 pension, it will follow that equal cause* produce 

 unequal effects, which i* absurd.*' " Having shewn," 

 continues he, " the insufficiency of this hypothesis, I 

 come now to the real cause of the phenomenon, which 

 is the attraction of the periphery or section of the sur- 

 face of the tube to which the upper surface of the wa- 

 ter is contiguous and cohere*. For this is the only 

 part of the tube from which the water must recede 

 upon its subsiding, and consequently the only one 

 which by the force of its cohesion or attraction oppose* 

 the descent of the water. This is also a cause propor- 

 tional to the effect which it produces, since that peri- 

 phery and the column suspend**] are both in the same 

 proportion as the diameter of the tube." Dr Jurin nf- 

 terward* account* for the spontaneous ascent ot the 

 water. He suppose* that the water which first enters 



\ 



Set rbiL Trans. 1 Tit, voL xxtli. p. Mfc 



