entertaining definition

When tractors were first developed, they used enormous steam engines which were notoriously unreliable and challenging to maintain. These were phased out round the turn in the 20th century and substituted with internal combustion engines that have been more compact yet still powerful and ran on the variety of fuels including kerosene, ethanol and gasoline. By the 1960s many of these engines were phased out and only more effective internal combustion engines that ran on diesel and after this, biodiesel. The practical options for energy range from the standard fuels, natural gas, petroleum (or oil), and coal. Fossil fuels are referred to as nonrenewable energy sources because, once used, they are gone. Scientists are exploring the practicality of other sources called renewable energizes. These include sun, wind, geothermal, water, and biomass. The renewable power resources are very important in long range energy planning simply because they will not be depleted. William and the friend Jason bring their bicycles on the attic, shrink themselves, and embark on a journey. They meet Sir Simon because he is getting ready to leave for the tournament, and so they stop at his castle. They spend more time a boy plus a girl with the castle and together. The girl tells them of an omen her grandmother, Calendar, kept repeating before she died. Sir Simon sent Calendar away for the convent as he thought she was crazy and he does not believe the omen. Few accept it but Calendar's granddaughter does. Jason and William believe it too.