de Prony brake dynamometers at a tractor contest in 1910. Schematic of a de Prony brake. The de Prony Brake is a simple device invented by Gaspard de Prony to measure the torque produced by an engine. The term  brake horsepower  is one measurement of power derived from this method of measuring torque. (Power is calculated by multiplying torque by rotational speed .).
Typically tree trunks are thought of as being in various shades of brown. They can have many different colours to them, however.Grey is a common colour in tree trunks, as is green when they're younger. Specific species of trees usually have specific bark colour at specific times of year so you should look up the trees you're interested in if you need more information.ypically tree trunks are thought of as being in various shades of brown. They can have many different colours to them, however.
Trunk and bark detail. The tree can grow to 45 metres (148 ft) tall; it has smooth bark, ranging in colour from white and grey to red-brown, which is shed in long ribbons. The tree has a large, dense crown of leaves.The base of the bole can be covered with rough, reddish-brown bark.t is a plantation species in many parts of the world, but is native to Australia, where it has the most widespread natural distribution of Eucalyptus in Australia, especially beside inland water courses.