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.
Oh I like red itâs the color of an apple. Orange itâs the color of an orange. Yellow its a lemon and a wonderful sun, sun, sun. Green its the color of the trees and lots of things that grow. And then there's blue for the sky. And purple thatâs a color thatâs fun, fun, fun. And when you put those colors side by side. Now what do you think weâve done. Weâve made a rainbow. And itâs a really beautiful one, one, one. Oh I like red itâs the color of an apple. Orange itâs the color of an orange. Yellow its a lemon and a wonderful sun, sun, sun. And my favorite. Green its the color of the trees and lots of things that grow. And then there's blue for the sky.