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.
Choose a shade tree that provides fall color. Enjoy the trees leaf displays for three seasons, spring, summer and fall by choosing a fall color tree. Most tree descriptions will contain the words fall color for trees that are showy in the fall and most of these descriptions will give the predominant color of the leaves.There are numerous cultivars of trees that are specifically selected for fall color exhibitions.ost tree descriptions will contain the words fall color for trees that are showy in the fall and most of these descriptions will give the predominant color of the leaves. There are numerous cultivars of trees that are specifically selected for fall color exhibitions.