Sentence:  Behind the hair is fixed a brass plate, which I call a bolster, because it stays the hair whilst it performs the work, and then the cane or chain is taken through all " the tackle, and fastened to a breast roll, and set to work " with double <WSD>mounture</WSD> of all sorts (videlicet) sixteen tumblers, sexteen lamms or countermeshes, and nine treadles. 
Meaning of the word marked with <WSD> tags:  A part on any mechanical device that is used for mounting other parts.