Analysis of the authorities upon which the dangers have been inserted in Blunt's new chart of the Atlantic, or Western Ocean : To which is added, an accurate table of the variations of the magnetic needle, as observed in different parts of that sea; with the dates of the respective observations. : And a series of experiments and observations, tending to prove, that by ascertaining the relative heat of the sea-water, by use of the thermometer, 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. : With an exhibition of facts, showing the progress of ice islands from Greenland to Newfoundland, &c.&c. / Compiled by Edmund M. Blunt, author of The American coast pilot.