144 Prof. A. Anderson and Mr. J. E. Bowen : Method of 



and the vernier read. The liquid is then poured into the 

 vessel and takes up a position somewhat as shown in the 

 figure : in these preliminary readings, in order that all our 

 readings for each tube might be taken with the apparatus in 



Fig. 1. 



M 



C^ 



■Jr- 



C,. 



position, it was usual in the case of liquids which rise in 

 tubes to fill the tube to the top and then take out a little of 

 the liquid from the vessel until the top of the meniscus is 

 just below the top of the tube ; the radius of the tube at the 

 top was then taken as the radius at the top of the meniscus. 

 The microscope is now focussed upon the image of 

 formed by refraction at the meniscus, and finally upon the 

 centre of the meniscus. The three readings give u and v the 

 distances of the object and image from the centre of the 

 meniscus, and from the formula 



where fx is the refractive index of the liquid, the radius of 

 curvature R at the centre of the meniscus can be found. 

 The meniscus being a surface of revolution the curvature of 

 any vertical section is the same, hence 



2T 



15- =the difference of pressure on the two sides —gph, 



