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.
There are two main Types of Trees based on their leaves, deciduous and evergreen; 1  Deciduous trees are trees whose leaves loose their green coloring and turn orange, red or brown before they are shed at the end of the growing season, generally in autumn.2  Evergreen trees carry their leaves throughout the year.n fact the term type of tree is very vague, as there are many types of trees in many different contexts. Regarding Botanical Classification, each Genus has a type species that is identified as a typical species for that genus.