Thermometrical navigation [electronic resource] : Being a series of experiments and observations, tending to prove, that by ascertaining the relative heat of the sea-water from time to time, the passage of a ship through the Gulph Stream, and from deep water into soundings, may be discovered in time to avoid danger, although (owing to tempestuous weather,) it may be impossible to heave the lead or observe the heavenly bodies. Extracted from the American Philosophical Transactions. Vol. 2 & 3. With additions and improvements. [One line from Poor Richard].