Records of other organs permanently installed and used in worship services in the late thirteenth and fourteenth centuries are found in large cathedrals such as Notre Dame, where in the 1300s you can find documents of organists being hired to work for the church as well as records documenting the installation of larger and permanent organs. The earliest record is a payment from 1332 from the clergy of Notre Dame to an organist to perform on the feasts St. Louis and St. Michael. The Notre Dame School also shows how organs could have been used within the increased use of polyphony, which would have allowed for the use of more instrumental voices within the music. This shows that by this point in time organs were being fully used within church services and not just in secular settings. There is proof that organs existed earlier in the medieval period, based on the surviving keyboards and casings of some organs, however no pipes from organs survive from this period. Until the mid-15th century, organs had no stop controls. Each manual controlled ranks at many pitches, known as the "Blockwerk." Around 1450, controls were designed that allowed the ranks of the Blockwerk to be played individually. These devices were the forerunners of modern stop actions. The higher-pitched ranks of the Blockwerk remained grouped together under a single stop control; these stops developed into mixtures.