India ink is a mixture of lampblack and glue. Equal-area projections, as the name implies, accurately represent area, but not shape. This type of projection shows area distributions such as vegetation, in which the area shown is critical.
Conformal projections retain correct shapes.
An added advantage is that, if shape is retained, so is direction. Longitude, as noted earlier, poses greater difficulties. It is known that the 360 degrees of longitude divided into the 24 hours of the day means that each hour is equivalent to 15 degrees of longitude. Thus, if the time at a known point could be maintained on a ship at sea, longitude could be calculated based on the time difference as established locally from the occurrence of the noon Sun. The problem, until John Harrison's invention of the reliable marine chronometer in 1761, was that no clock was able to retain its accuracy under the difficult conditions of a sea voyage.