Sluice gate hatch

Milan's canal and weir system had been built two centuries before Leonardo's arrival in the city. He was fascinated by these waterways and endeavoured to make improvements to the existing system. One such improvement was an opening and closing mechanism applied to the sluice gates. It consisted in a hatch provided with a padlock that could be operated from above. By means of this device, the flow of water in the weir could be reduced or increased, thereby balancing the pressure at the sides of the sluice gates and making it easier to open them.