In pilotage and position fixing, a transit, in British English, or range, in American English, occurs when an observer and two fixed reference points form a straight line. A transit of known reference points creates a position line which can be plotted on a map or nautical chart. The intersection of two position lines form a known position.
The further apart transit reference points are, the more sensitive the visual effect is to lateral movements of the observer. If the points are near to each other, larger lateral movements of the observer are needed to show up as changes in alignment. Transits can be formed from natural features or they can be deliberate navigation aids such as leading lines.
Transits usually rely on visual reference points. That can be their downfall; darkness, fog, other forms of precipitation or physical barriers can make them unusable. Leading lights are a way of providing transits at night.
Famous quotes containing the word transit:
“We only seem to learn from Life that Life doesn’t matter so much as it seemed to do—it’s not so burningly important, after all, what happens. We crawl, like blinking sea-creatures, out of the Ocean onto a spur of rock, we creep over the promontory bewildered and dazzled and hurting ourselves, then we drop in the ocean on the other side: and the little transit doesn’t matter so much.”
—D.H. (David Herbert)