Masonry oven these primitive-looking ovens were still being produced in Barnstaple potteries as late as 1890". A cloche or cooking bell is like an upside-down, fired ceramic bowl with a handle on top. It is heated in the fire along with a flat rock or open spot on the hearth. The prepared dough is placed on the hot rock or hearth floor, and then covered with the cloche, and perhaps hot coals or ashes for additional heat. The method goes back to ancient Egypt and Greece, and was probably the first form of masonry oven. It is possible to get some of
Ceramic capacitor as precision oscillators and timers. On the other hand, for general applications such as non-critical filtering or coupling circuits, for class 2 capacitors the tolerance series E12 down to E3 are sufficient. Capacitance of ceramic capacitors varies with temperature. The different dielectrics of the many capacitor types show great differences in temperature dependence. The temperature coefficient is expressed in parts per million (ppm) per degree Celsius for class 1 ceramic capacitors or in percent (%) over the total temperature range for class 2 capacitors. Most discrete capacitor types have greater or smaller capacitance changes with increasing frequencies. The dielectric strength