The second one is charging hourly. We tend to prefer hourly fees on projects that are particularly open ended or very small scope. Our hourly rates are currently between $60 and $120 per hour depending on who is doing the work.
The word sonder exists, though. It means to probe, and in a more specific use, to test the depth of something. The word sound (as in the water feature) is a cognate, both related to the Old English sund meaning to swim, or the sea. I can't really think of an English equivalent that's specific beyond mere awareness.
a rheological term taken from the rheometer reading performed by a Mud engineer on drilling fluid and it is expressed in the centipoise. Centipoise is the level of force needed to move one layer of fluid in relation to another. APPARENT VISCOSITY: The apparent viscosity applies to non-Newtonian fluids..