For example, for the Gases under pressure hazard class, the hazard categories are Compressed gas, Liquefied gas, Refrigerated liquefied gas and Dissolved gas. These classes relate to the physical state of the gas when packaged and do not describe the degree of hazard.
1 In 1596, a flush toilet was invented and built for Queen Elizabeth I by her Godson, Sir John Harrington. 2  The first patent for the flushing toilet was issued to Alexander Cummings in 1775. 3  During the 1800s, people realized that poor sanitary conditions caused diseases.
The flush toilet makes use of some hydrodynamics so it makes this a bit tricky, but I'll try to abstract away the fluids and simply represent them as forces. The flush toilet makes use of two separate levers and no other simple machines. The first lever is applied by the operator using the handle. In this case, the fulcrum is located at a midpoint between the ends of the lever. Connected to the handle is a moment arm which is connected to a chain.