THE MYSTERY OF MARINE DISASTERS.

Thames Star, Volume III, Issue 1677, 19 May 1874, Page 2

THE MYSTERY OF MARINE DISASTERS.

A most startling inquiry has recently been raised in England regarding a new theory of the cause of deviation in the mariner's compass. Hot long since a writer in the Nautical Magazine, a very high authority on marine matters, advanced some remarkable facts tending to ; ; shew ; that; in ".iron? steamships one hitherto unsuspected source of magnetic deviation is the; distribution of heat over the metallic hull He illustrated his meaning by citing the case of an iron steamship, going up./the Bed Sea, which had the rays of a blazing sun impinging on one side of: her hull in the morning, and on the other side in the evening, the effect being a very marked, difference ,in- ' the morning and evening deviation. Again is cited the, case- of fan iron steamship making a passage from Liverpool to •New York, and when in the internate bands of tepid Gulf Stream and frigid Polar water, the master found a compass alternation of ten degrees. A similar deviation has been observed on board vessels lying in port when the sun has ■ been shining powerfully on one side of the^ship, and the; other has been-shaded. I An* experiment in thermal electricity shows that if different parts of a metallic bar be unequally heated, or if one part be cooled by application and the other heated by a spirit lamp, the electricity is proportionate, not to the absolute • heat conimuriicated, but to the difference of temperature in different parts of the body. But as yet no experiments have been conducted to test the'correctness of this novel view, and to determine how far, if at all, under the conditions named the magnetic guide of the seaman may lead him- ruinously* as tray. Now strange to say. the writer of the article, who modestly suggested merely putting his views and deductions to a crucial test, has been sharply overhauled for his presumption in proposing such magnetic inquiry. I The 1* venerable head of the Admiralty Compass Department severely criticises him on the ground that his own observations have brought no such result to light, and dismisses the theory as not holding water. But, ? despite. the weight of such high authority, the facts stated and their consonance with a known law of thermo-electricity,' as well as the difficulty of explaining < many compass deviations in iron ships 1 upon any principle heretofore propounded by scientists, i warrant and demand some satisfactory, if not exhaustive, experiments to deqide the question 'atf'issue .—New York Herald. ;