- -10% provincial capital and minor settlement main chain construction costs
- -1 provincial capital and minor settlement main chain construction times
The dioptra was first used by the Greek astronomers to fix the position of the stars. However, when this was superseded by a more accurate device, the armillary sphere, it found a new function as a surveying tool. It was a portable instrument that could be used to measure distances, angular measurements or work as a level. The dioptra could assess both the horizontal and vertical planes, allowing for readings of the deviation between two set locations, so offering accurate measurement of any angles involved.