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§ 2. HOW TO MANAGE YOUR SHIP IN A TYPHOON.

Long before the nature of hurricanes was understood it had been remarked by mariners that it was safer to heave to in a storm than to run, but the reason of that was not apparent. When the law of storms was first discovered it did not all at once mend matters, for, according to the old eight-point rule, all you had to do when a typhoon approached was to run with the wind on the star-board beam under as much canvas as your ship could carry, except when on the path right in front and the centre moved quicker than the vessel. That should have taken you out of the neigh- bourhood of bad weather, but it did not always do so, and since typhoons have been investigated, we know that the wind never blows round the centre in a circle, and that the eight-point rule, laid down by Redfield, Reid, Thom, and Piddington, is very far from the truth. It is just as much out as Espy's rule, according to which the wind blows always straight towards the centre. According to the twelve-point rule, which I have proved to obtain in typhoons (see "Observations and Researches made at the Hongkong Observatory in 1885") you must still run on the starboard tack, but you must keep the wind only four points from the stem. A steamer can do so easily enough, but it is not possible to keep a vessel going ahead under square sails nearer than about six points to the wind. She therefore cannot within two points run straight away from the ceatre and her risk is much greater than it would be if the old rule had proved true. The twelve-point rule may be stated as follows:-Stand with your back to the wind and you will have the centre on your left and about four-points in front of your left-hand. It appears that a ten-point rule obtains in about 30 degrees latitude and a sailing vessel can then just manage to steer, full and by, a course that will take her straight away from the centre; but in a tropical hurricane we see that the danger is much greater even if the force of the wind were not stronger.

The force of the wind and the appearance of the weather do not furnish a trustworthy guide to determine the distance of the centre of a typhoon. The dimensions are different in almost all typhoons, and near land the strong winds are often so irregularly distributed that in a place near the centre less wind may actually be experienced than at some distance farther away from it. In such cases the approach of the centre is judged of by the fall of the mercury in the barometer.

But on the high sea the increase or decrease in the strength of the squalls, and the state of the weather and sea, enable the approach of the centre to be known, and this, together with its direction which is known from the direction of the wind and perhaps also from the clouds, enables the master of a vessel at sea to lay down the path of the typhoon, with reference to his vessel, with more or less accuracy. The great difficulty is, that the typhoon may be increasing or decreasing in violence and the barometric depression getting steeper or filling up. To the eastward of the Philippines and near their western shores the former is likely to take place, while the latter would probably happen near the western shores of the China Sea. In such cases it may become more or less impossible for a seaman to know how the centre moves, except in so far as he can judge by published paths of previous typhoons.

Once the bearing of the centre has been ascertained from the direction of the wind, you require to know in which semi-circle your vessel is situated: if in the right-hand semi-circle the wind will veer, ie., shift with the sun, and in the left-hand semi-circle it will back, i.e., shift in the opposite direction. But this rule fails if your vessel is moving with the typhoon and quicker than the centre is moving. Then the rule may be reversed. Masters of vessels are therefore advised to heave to early and observe how the barometer behaves and how the wind changes; but it is so dangerous to lose any time in a storm that carries you into the centre, that this should not be done except when absolutely necessary. You may happen to be right in front of the centre and lose your chance of getting out of its track. Here it is that a knowledge of the paths of past typhoons such as have been annually published from this Observatory during the past fourteen years, becomes so useful. That may enable you to know at once in which semi-circle your vessel is situated, e.g., with NE wind in the China Sea you are pretty certain to be in the right-hand semi-circle. The wind shifts faster the nearer the centre you are, but the direction of the sea does not change so fast as the wind. If the bull's eye of the typhoon overtakes your vessel, the wind bursts again from the opposite quarter, and with perhaps greater violence than before, that is, when the centre is past. Very deceitful lulls occur during the raging of a typhoon and last sometimes long enough to be mistaken for the central calm, but in such a case the wind bursts again from about the saine direction as before.

The rate at which the barometer falls depends upon your approach to the centre, and in con- sequence upon the rate at which the latter is travelling. You cannot therefore safely draw conclusions concerning the amount of wind to be expected from the rate at which the barometer is falling, but to some extent that may be done. Remember that at sea when the barometer has fallen to the lowest point and is beginning to rise again, you may expect as much, if not more, bad weather than you have already gone through although it will be, on the whole, improving.

The right-hand semi-circle is called the dangerous semi-circle; there you are carried not only in towards the centre, but also towards the path in front of the centre; besides, the force of the wind is greatest in the right-hand semi-circle, but fortunately the wind usually veers in the squalls in the same direction as it veers with the progress of the typhoon. Here you must make up your mind at