In 1700, the Italians were the most technologically advanced in silk throwing in Europe, and they had developed two machines capable of winding the silk onto bobbins while putting a twist in the thread. They called the throwing machine, a "filatoio", and the doubler, a "torcitoio". There is an illustration (drawn in 1487) of a circular handpowered throwing machine with 32 spindles. The first evidence of a externally powered filatoio comes from the thirteenth century, and the earliest illustration from around 1500. Filatorios and torcitoios contained parallel circular frames that revolved round each other on a central axis. The speed of the relative rotation determined the twist. Silk would only cooperate in the process if the temperature and humidity were high, in Italy the temperature was elevated by sunlight but in Derby the mill had to be heated, and the heat evenly distributed.