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National Geographic : 1904 Apr
Contents
THE NATIONAL GEOGRAPHIC MAGAZINE locity of 15 miles per hour, and capa ble of imparting to a full-rigged ship sailing " full and by " a speed of from .3 to 4 knots. THE MEXICAN BELT OF CALMS. From an inspection of these diagrams it is evident that the "'Mexican Belt of Calms," as it is known among seamen, is triangular in shape, the base of the triangle resting on the American coast, and extending from the Gulf of Cali fornia to the Gulf of Panama, the ver tex of the triangle lying far out in the Pacific, its longitude roughly coinciding with the meridian I25° W., near the fairway of vessels bound from San Francisco to the line. In latitude, the position of the vertex, as well as the axis of the belt, or line along which the maximum frequency of calms occurs, changes slightly with the season. From November to April its mean position is between 5° and Io° N. As the summer advances and the sun moves northward, however, the axis of the belt likewise recedes from the equator, its average position for the months May-October lying between io°-I5° north. The fre quency of calms increases rapidly as the coast is approached. Immediately under the coast, however, a diminution may in some instances be noted, due to the presence of the land and sea breezes, and also to the fact that at certain points the trade wind of the Caribbean seems to reach across the Isthmus. A REMARKABLE CASE OF POCKETING. A single example-an extreme case, however-will serve to illustrate the delay to which a vessel may be sub jected in the endeavor to navigate this dead-center of the winds. The German bark Arcona sailed from Punta Arenas, a point on the Isthmus somewhat to the west of Panama, December 3, 189o, bound for Hamburg. Upon leaving port light southwesterly winds were encountered, interrupted by frequent periods of calm, and with these the bark made the best of her way, on the starboard tack, to the southward. On December o1, her position at the time being latitude 6° N., longitude 840 W., the wind still holding from the south west, the vessel went about on the op posite tack in the hope of obtaining better conditions to the westward. Thirty-two days later, or on January ii, 1891, the position was latitude 50 N., longitude 88° 40' W., the total dis tance made good during the 39 days since leaving port amounting to but 350 miles. The strong northeasterly cur rent flowing in toward the Gulf of Panama set the vessel as far back each day as the light airs carried her for ward, and it was not until January 27, 55 days out, that she finally succeeded in crossing the equator in longitude 960 west. In both approaching and in leaving Panama, irrespective of the port from which or toward which bound, a sail ing vessel must of necessity navigate a greater or less width of the belt of calms just described, and in estimating for a given voyage the saving of time effected by the use of the canal the de lay arising from this cause must not be neglected. THE OCEAN HIGHWAYS OF SAILING VESSELS As organized at present, the sailing traffic of the world is confined to certain well-beaten highways, dictated in part by the physical agency of the winds and in part by the demands of trade. Tak ing the English Channel and the port of New York as points of departure, the most frequent destinations are, to the westward (by way of Cape Horn), the Pacific coast ports of South, Central, and North America, and, to the east ward (by way of the Cape of Good Hope), the ports of South Africa, Aus tralia, and Eastern Asia. Outward bound vessels in general carry a mixed 174
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