Hydraulics

A Greek mathematician called Ctesibius, living in Alexandria, Egypt in around 250BCE created a musical instrument called a 'hydraulis' or 'hydraulikos', meaning 'water organ', or 'water pipes'. Air was pumped into a bladder that was held below the water; the pressure of water on the air was used to blow it through organ pipes to create music

Over the course of time, the word 'hydraulics' has come to mean the science and engineering principles around using liquids to perform work. Note: liquids, not gases so, in modern terminology, Ctesibius' invention was rather a pneumatic organ, or at least a hydro-pneumatic organ

My first encounter with the word was in childhood, when "the hydraulics" always referred to the three points on the back of a tractor where a 'mounted' (rather than 'trailed') farm implement was attached. I had no understanding that 'hydraulic' referred only to the oil pump, pipes and rams that controlled the up and down movement of the mechanism, rather than the arms, pins and screws of the mechanism itself

The pourous limestone rock from which our house is built has, in effect, lots of little pipes in it, through which water can pass. At the scale of those 'pipes', the molecular forces that create capillary action are very effective in drawing water through the rock. I'm not sure if this counts as hydraulics or not, but it was certainly enough to force the old plaster off the wall, and prevent new plaster drying out thoroughly. This trench (which will be filled with free-draining stone) is the next attempt to solve the problem - ensuring that damp soil is not cheek-by-jowl aganst the wall

Watching the hydraulically powered arm of a mini-digger create a hole beside the rudimentary 19th century footings ('foundations' would be too strong a word!) of your house is an adrenaline-generating experience. The effective hydraulics of my circulatory system have made sure it is well distributed around my body. Tonight's rest may be somewhat fitful