The Principles of Sound Survey
Lead and line, faithfully recorded
Every depth taken by hand and reduced to chart datum — the mariner reads what the sea floor truly presents.
The shore traced upon the falling tide
Coastal detail committed when the water stands at its least, exposing every rock, ledge, and shoal to the surveyor's careful eye.
Variation observed, never assumed
Compass error determined at each station and inscribed as isogonic curves across the finished chart sheet.
Relief rendered by the graver's art
Elevation expressed through the density of fine ruled strokes, legible to the pilot approaching a foreign landfall.