An Encyclopedia of the History of Technology part 28. This one of a kind encyclopedia presents the entire field of technology from rudimentary agricultural tools to communication satellites in this first of its kind reference source. Following an introduction that discusses basic tools, devices, and mechanisms, the chapters are grouped into five parts that provide detailed information on materials, power and engineering, transportation, communication and calculation, and technology and society, revealing how different technologies have together evolved to produce enormous changes in the course of history | PART TWO POWER AND ENGINEERING Figure The paltrok De Poelenburg at Zaandam. This saw mill was built in 1869. The brick base on which the whole mill rotates is visible behind the ladder and winding windlass. The crane for lifting the logs onto the stage is on the left. Anders Jespersen. hauled up on to the carriage by means of a crane at the entrance end of the carriage. The chain on the crane is wound up by a windlass driven by the sails through the drive shafts of the carriage. The saw frames consist of double top and bottom bars separated by about 25mm 1in . In this gap the saw ends are slotted and are separated by amounts equal to the thickness of the timbers to be cut. The saws are tensioned by wedges driven into sockets in the ends. These saws are extremely powerful and at d Heesterboom the smock saw mill in Leiden built in 1804 and still used the wind-driven saws are used for logs of 600mm 24in or more in diameter. Figure shows the paltrok De Poelenburg of 1869. 252 WATER WIND AND ANIMAL POWER The paper-making windmills are exemplified by De Schoolmeester at Westzaan in North Holland a thatched smock mill with a reefing stage a tail pole and windlass where fine white paper is made from rags. The drive comes from the cap right down to ground level where the machinery is situated. The rags are sorted and cut by hand against fixed knives in order to reduce the pieces to a manageable size. The rags are then chopped to finer particles in a tub with a strong wooden bottom in which four knives on poles are lifted and dropped by means of cams and they are then soaked in a caustic solution and placed in the hollander . The hollander is a long tub with semicircular ends and a spine down the centre. On one side of the spine the floor of the tub rises to meet the underside of a drum which is covered with blades along its length and around the rim. The fluid of rags chemicals and water is pushed around the tub by the motion of the drum. As the fluid passes under .
