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.
Forest green refers to a green color said to resemble the color of the trees and other plants in a forest. The first recorded use of forest green as the name of a color in the English language was in 1810.ine green is a rich shade of spring green that resembles the color of pine trees. It is an official Crayola color (since 1949) that is this exact shade in the Crayola crayon, but in the markers, it is known as crocodile green.