To prevent warping, thin, organic bonded wheels such as those used for cutting-off should be laid flat on a horizontal surface of steel or similar rigid material away from excessive heat and moisture.22 To minimise deterioration, wheels must be stored in a room which is dry and not subject to extreme temperatures.
A great intellectual and cultural development in Europe and the United States is the source of many discoveries, inventions and revolutions, for example: Declaration of Independence of the USA or French Revolution. It's also the time of philosophers - like Montesquieu, Voltaire, Jean-Jacques Rousseau, Diderot or d'Alembert - who all focus on the same subject: the questioning of political structures and traditional value systems such as religion, absolute monarchy, education, science etc.
