 
 <prompt> Wetin dey happun wen di liquid stop to dey go up or down? Given di previous question, write one context wey contain di answer. E fit be 1 - 20 sentences. Context: <response>: Hydrostatic gauges (like mercury column manometer) dey consist of one vertical column of liquid inside one tube wey dey exposed to different pressures. The column go rise or fall until e balance with the pressure difference between the two ends of the tube. The simplest design na one closed-end U-shaped tube, one side wey dey connected to the region wey dey of interest. Any fluid fit dey used, but mercury dey preferred because of e high density and low vapour pressure. Simple hydrostatic gauges fit measure pressures wey dey range from 1 torr (100 Pa) reach above atmospheric. One important variation na the McLeod gauge wey isolate one known volume of vacuum and compress am to multiply the height variation of the liquid column. The McLeod gauge fit measure vacuums as high as 10−6 torr (0.1 mPa), wey be the lowest direct measurement of pressure wey fit happen with current technology. Other vacuum gauges fit measure lower pressures, but na only indirectly dem fit do am by measurement of other pressure-controlled properties. These indirect measurements gats dey calibrated via one direct measurement, wey most commonly na McLeod gauge. 