This may not look to be a very exciting picture, but it is an illustration of the ingenuity of 19th century engineers. The pipe is not made as one unit like modern pipes. It was made from a single sheet of wrought-iron which was bent physically into a round shape to form the pipe. Then, using the same technique as in ship-building, the pipe was joined along its length using hot rivets. A similar technique was applied to join the pipes together.