Resources Heritage Canals & Waterways The canals within the Gunpowder Mills played a vital role in the manufacture of explosives. The Millhead stream drew water from the Old River Lea at the northern extremity of the Mills. This channel, running down the western edge of the site, provided the head of water which was used to drive all the water-powered mills. By the nature of a powder factory, it was important that the buildings were spaced well apart to lessen the possibility of chain reaction should a building explode. These canals made transport of the sensitive materials between the process buildings much safer, carried in boats on the smooth surface of a canal, rather than in carts over bumpy roads. Even after the arrival of steam driven mills in the mid-nineteenth century, canals were still built as part of the transport system which, by the 1890s, reached it maximum extent of over ten miles. The three levels within the site were linked by locks, two of which still survive. Cast-iron aqueducts were built to carry the canals over the channel of the old River Lew, which meanders through the Mills site. One of the powderboats has been restored by the Friends Association and can be found in the Green Hut, about 5 minutes' walk from the main visitor area. These boats carried the process materials around the canal system, always man-hauled by rope from the bank. Horses were never used on site. Perhaps the possibility of a horse bolting with a boat loaded with explosives, gave pause for thought. Many of the canals are now dry, although this does not minimise their powerful presence in the landscape. We hope that in time funds can be found to restore them and fill them once more with water. Canal System Map The Canal System The Millhead Stream was used as a canal for the smooth and safe delivery of raw materials and collection of gunpowder. By 1800 the system had been further extended by the building of new mills on the banks of the old River Lea and the connection of these to the Millhead by canals. In 1806, the Powdermill Cut was dug to connect the Mills directly to the new Lee Navigation and enabled the transport of gunpowder by barge from the Grand Magazine at the north end of the Mills to the arsenals at Woolwich and Purfleet. Gradually the system was enlarged until virtually all the process buildings were served by a waterway and the total length of canal exceeded 5 miles. The Lock The canal lock was built in 1878-9 to link the two levels of canals that had developed within the Gunpowder Mills since the late 1700’s. The difference between the two levels was 6 feet, which gave sufficient head to drive the water wheels of the process buildings situated along the edges of the upper canals. The higher water level can be seen from the white marks on the brickwork of the upper curtain wall. The lower level was about 6’’ higher than the existing water level to the right. The sluices or paddles which admitted water to the lock can be seen on the left hand end of the structure. Those on the right were for emptying the chamber. The use of this lock gave boats carrying raw materials or part or finished explosives access to all parts of the Mills. One of the Powder Boats which used this lock is on display in the "Green Hut" (building L185) on the Long Walk. The Aqueduct The cast iron channel you can see ahead is one of two aqueducts built in 1878-9 to carry the extended high level canal system over the natural waters of the original River Lea (or Barge River as it was called up till 1770, when the Lee Navigation was built over to the west). Both these aqueducts are made from three huge cast iron plates (the base and two sides) brought by barge and then lifted and riveted on site. The original water level is marked by the white discolouration caused by the chalk in the water. There is a third aqueduct near Newton’s Pool of a slightly different design. There are only 26 cast iron aqueducts in Britain. Three of these are in the Gunpowder Mills. The Mill Head Stream The Millhead formed the main power source for the water driven mills located in this area, even before the first gunpowder mills were recorded in 1662. The Millhead was built to provide a 6 foot head of water to drive the water wheels which powered the various process buildings. By 1735 a series of mills and ancillary buildings are shown in the drawing of John Walton’s Gunpowder Works, all built along the Millhead and draining to lower level leats on each side. The sluice below is possibly part of Smeaton’s Mill. More information about the canal system is available on the Lee and Stort Navigation website... Manage Cookie Preferences