Tubes of various sizes and shapes are connected to a common reservoir at their bottoms. The level of the fluid in each tube is the same as the others.
References: Hetch Chpt. 11 Fig 11-4,11-5;
Halliday and Resnick, Chpt. 15, Fig. 15-6
This demo can be found in cabinet D on shelf 2 of the UCSD PUL Demo Room
(WLH 2015).