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.
Share. By Laura Klappenbach. The red-eyed tree frog (Agalychnis callidryas) is a vibrantly colored frog with large red eyes, a green body and light blue sides with yellow strips. Its feet are bright orange and its legs are mostly green. The underside of the red-eyed treefrog is a light-cream color.Young red-eyed tree frogs are brown and gain their distinct coloration as they mature. Adult red-eyed tree frogs can temporarily change their color to a darker green or reddish brown color. The red-eyed tree frog has a delicate build.he underside of the red-eyed treefrog is a light-cream color. Young red-eyed tree frogs are brown and gain their distinct coloration as they mature. Adult red-eyed tree frogs can temporarily change their color to a darker green or reddish brown color. The red-eyed tree frog has a delicate build.