192 steam vessel with the wind a little on the starboard bow. By so doing, if the vessel makes any headway she increases her distance from the centre; she also follows the wind movement to the right and heads the sea, and the storm moving along the line of progression increases the distance between the vessel and the centre of the storm. (b) In the least dangerous semicircle there is liberty of action. The wind can be brought on to the starboard quarter or more abeam if possible, thus rapidly increasing the distance between the vessel and the storm centre. (c) When on the line of progression the least dangerous side should be entered with all possible speed (see "Concise Rules for Revolving Storms"). AB the most dangerous quadrant; ABC the most dangerous semicircle; ADC the least dangerous semicircle; PAC the line of progression. Diagram showing the rotary motion of a circular storm in the Northern Hemisphere. If the storm remained stationary, as they sometimes do, there would be "no shift of wind," only an alteration in direction as the vessel sailed towards or from the centre of the storm. In such a case in the Northern Hemisphere the ship should carry as much sail as she could with the wind as far as possible forward on the starboard side. In the Southern Hemisphere take the wind on the port side and make as much distance as possible. Stationary cyclones are most common in the Indian Ocean at the beginning and end of the season. The problem seems complicated, because in most cases the storm has a progressive motion, and this causes the wind to shift as the storm passes over the vessel. It should be understood that the rotary motion of the storm causes the wind to fly from the circumference in a constant direction, therefore the wind is always to be found from the same direction in the same part of the storm-field. Because of the progressive motion the seaman has no liberty of action when on the most dangerous side; he can only hang off to the best of his ability, whereas when on the least dangerous side he may run away from the storm-centre, that is, if there is sea room. GENERAL NOTICES Concise Rules for Revolving Storms I. Revolving storms are so named because the wind in these storms revolves round an area of low pressure situated in the centre. They have also local names, and are termed hurricanes in the West Indies and South Pacific Ocean, cyclones in the Indian Ocean, Bay of Bengal, and Arabian Sea, and typhoons in the China Sea. 2. In these storms the wind always revolves in the same way in the same part of the world; that is, against the movement of the hands of a watch in the Northern Hemisphere, and with the hands of a watch in the Southern Hemisphere. The wind does not revolve in circles, but has a spiral movement, inwards towards the centre. 3. Revolving storms have also, as a general rule, a progressive movement. Within the tropics they usually move from east to west at first, and then curve towards the pole of the hemisphere in which the storm is generated, and afterwards move from east to west. 4. The track which the centre of the storm takes is called the path of the storm, and the portion of the storm-field on the right of the path is known as the right-hand semicircle, and that on the left as the left-hand semicircle of the storm. 5. In the right-hand semicircle, if the observer be stationary, the wind will always shift to the right, and in the left-hand semicircle to the left. This law holds good in both hemispheres. 6. If a vessel be so situated in a storm that by running before the wind the path of the advancing storm will be crossed, this is considered to be the dangerous semicircle. This will always be the right-hand semicircle in the Northern Hemisphere, and the left-hand in the Southern. 7. These storms are most frequent in the Northern Hemisphere from July to November, and in the Southern Hemisphere from December to May. In the Bay of Bengal and Arabian Sea they, however, occur most frequently about the time of the change of the monsoon. 8. The area over which revolving storms have been known to extend varies in diameter from 20 miles to some hundreds of miles, and their rate of movement in the West Indies averages about 300 miles a day; in the China Sea, Bay of Bengal, and Arabian Sea about 200 miles a day, the more stationary storms occurring at the beginning and end of the hurricane season. 9. The indications of the approach of a revolving storm are: (i) an unsteady barometer, or even a cessation in the diurnal range which is 104 constant in settled weather; (ii) a heavy swell not caused by the wind then blowing; (iii) an ugly, threatening appearance of the sky. 10. In order to judge what is the best way to act if there is reason to believe a storm is approaching, the seaman requires to know (a) in which direction the centre of the storm is situated, (b) in which semicircle the ship is situated. II. As these points cannot be determined if a vessel is moving with any speed through the water, the first proceeding should be to stop "heave to" and, as it is always best to assume, at first, that the vessel may be in a dangerous semicircle, she should be hove to on the starboard tack in the Northern Hemisphere and on the port tack in the Southern. 12. If an observer faces the wind the centre of the storm will be from 12 to 8 points on his right hand in the Northern Hemisphere and on his left in the Southern Hemisphere, 12 points when the storm begins, about 10 when the barometer has fallen of an inch, and about 8 points when it has fallen of an inch or upwards. 13. If the wind shifts to the right the vessel is in the right-hand semicircle; if to the left in the left-hand semicircle; and if the wind is steady in direction but increasing in force she is in the direct path of the storm. 14. If the seaman has reason to think that his vessel is in the direct path of the storm he should run with the wind on the starboard quarter in the Northern Hemisphere and on the port quarter in the Southern Hemisphere, until the barometer has ceased falling; this would take the vessel into the less dangerous semicircle in both hemispheres. If she is in the right-hand semicircle in the Northern Hemisphere she should remain hove to on the starboard tack, but if in the Southern Hemisphere she should run with the wind on the port quarter; if she is in the left-hand semicircle in the Northern Hemisphere she should run with the wind on the starboard quarter, but if in the Southern Hemisphere remain hove to on the port tack. 15. Should a vessel not have sufficient room to run when in the least dangerous semicircle, she should heave to on the port tack in the Northern and on the starboard tack in the Southern Hemisphere. 16. If in a harbour or at anchor, the seaman should be just as careful in watching the shifting of the wind and ascertaining the direction of the centre, as by doing so he will be able to tell on which side of the path of the storm he is situated, and be able to act according to circumstances. 17. Should the centre of a storm pass over a vessel the wind, after blowing furiously in one direction, ceases for a time, and then blows with equal fury from the opposite direction. This makes a pyramidal sea, which is especially dangerous. 18. Should the wind be west the vessel should remain hove to and the storm will pass away from her. Figures to denote force of wind. Rippled 71 High to II to 15 ft. very 16 to 35 ft. Rollers with steep fronts. Under Rocks small boat 91 Pheno buoys or ΙΟ menal 36 ft. and Precipitous; towering. Furrowed WIND FORCE. Description of wind. Mode of estimating on board sailing ships. wind in miles OCEAN CURRENTS The ocean currents are caused by the turning of the earth on its axis, by the differences of temperature in different parts of the ocean, and the prevailing winds; all of which cause a displacement of the water, while gravitation compels the restoration of equilibrium. There is therefore a close parallel between the air currents (wind) and the ocean currents, the more definite action of the water currents being due to its greater specific gravity. If the water were to flow continuously from one point, as the Gulf Stream, for instance, the gulf would run dry, but the outward flow is balanced by an inward flow from the equatorial current, which in turn is supplied by other currents from north and south, thus making a complete chain of currents the seas over. There is, in fact, two well defined systems of currents in the Atlantics. That to the north of the equator circulates with the hands of a watch, the centre of which is the Sargasso Sea. To the south of the equator the currents circulate against the hands of a watch; this circulation occurs in a lesser degree in the Pacific and Indian Oceans, thus forming the great ocean currents. Atlantic Ocean The equatorial current commences on the coast of Africa in the vicinity of Anno Bom Island between long. 2° and 8° E. and runs to the westward between 2° N. latitude and 10° S. latitude with an average velocity of 30 miles, but occasionally attains a rate of 60 to 70 miles a day. Off San Roque it splits, one part running to the southward forming the Brazil Current, which flows down the South American coast as far as Rio de la Plata at a distance of about 150 miles from the main; it then recurves to the eastward, forming the South Atlantic connecting current. The other part of the equatorial current flows along the north coast of South America with a velocity of nearly 100 miles a day and flows through the Caribbean Sea round the Gulf of Mexico and through the Straits of Florida, forming the commencement of the Gulf Stream. The Gulf Stream After leaving the Strait of Florida, where it is 50 miles wide, it gradually expands, flows to the northward for about 300 miles, then turns towards the north-east, then more east across the Atlantic right on to Norway. Off Cape Hatteras the width is about 120 miles, and beyond Bermuda 250 miles* wide. It attains its greatest velocity, 120 miles a day, in the Strait of Florida. The Arctic Current This flows out of Davis Strait over and around the Bank of Newfound land along the American coast inside the Gulf Stream. A part enters the Strait of Bellisle and flows down the western side of the island. Where the |