Critical line force tubes

In studying this critical line force we have chosen to use the device first described by Jamin as shown in Figure 1 [13]. This consists of a horizontally placed cylindrical tube containing a series or "chaplet of individual liquid indexes separated by air spaces. An air pressure differential is applied across the chaplet, and the velocity of the last index on the low pressure side is noted as a function of increasing pressure differential. 

The relationship between contact angle hysteresis and critical line force in this cylindrical tube system is easily derived from the geometry of the system and the Laplace equation for capillary pressure. It is... 

---