COS — =^ I ^ ^ .'/ . 



2 \ 4c^ • 



2 C'-i/^ 



2 c2 



69 



(4) 

 (5) 



Let us now suppose that the frame has vertical legs (as in Fig. 2) extending 

 downward into the liquid. Let / be the length between the legs. 



Jfiz 



E(|uation (1) becomes 



w = 2T(l — t) sin n -\- i>thj, 

 — 2 i>c'-{l — t) sin rt + 2 Itjic sin-^ 



(6) 



When «; is a maximum, -p- =o. Let t be verv small compared with /, then 

 'art • ' ' 



(I 

 2 c cos n + t cos -^ = o. 



Eliminating a by (4) and (5), and inserting the value of c, 



^ /' ^ A /«^ 2' 



When t is small, a near approximation is 



\ /> 



Supplying this value of y in (6), and solving for T, 



T = 



:+ 



pPf' 



It 



2(1 — 1} ' 4(1 — tr' 4(/-0- 



-1 i>'l-t^ +4u' / — <)/'. 



(7) 



(8) 



Table II gives the value of Tcalculated by the above formula for mica frames 

 varying in thickness from 0.0013 cm. to 0.02067 cm. 



