History of measurement units of length referred to above and the Mesopotamian cubit were used in the 3rd millennium BC and are the earliest known units used by ancient peoples to measure length. The units of length used in ancient India included the dhanus, or dhanush (bow), the krosa (cry, or cow-call) and the yojana (stage). The common cubit was the length of the forearm from the elbow to the tip of the middle finger. It was divided into the span of the hand or the length between the tip of little finger to the tip of the thumb (one-half cubit), the palm
Probe tip small tips in nanoscale due to resolution limitation of the optical microscopy. In electron field emission current measurement method, a high voltage is applied between tip and another electrode followed by measuring field emission current employing Fowler-Nordheim curves formula_6. Large fields-emission current measurements may indicate that the tip is sharp and low field-emission current indicates that the tip is blunt, molten or mechanically damaged. A minimum voltage is essential to facilitate the release of electrons from the surface of tip which in turn indirectly is used to obtain the tip curvature. The downside of this method to the several advantages