Page:TASJ-1-1-2.djvu/100

 below; and this being unable to escape as the barometer fell, owing to the tightness of the hatches, eventually, when the barometer fell very low, and consequently the outside pressure was partly removed, expanded and forced up the hatches, or such portions of the deck confining it as happened to be weakest. This would not have occurred a second time, as an equilibrium of forces was soon established, and the pressure equalized on both sides.

There are two essential rules of vast importance to the seaman to be remembered in connection with circular gales, and which will always be a sure guide.

The first of these is: That the wind in the right hand semicircle always changes to the right of the point from which it blows, and the second: That the wind in the left hand semicircle always changes to the left of the point from which it blows.

This is true in both hemispheres.

Two other rules should be remembered as equally important. The first is: That in the Northern Hemisphere the bearing of the centre of the gale is always eight points to the right of the direction of the wind—as when the wind is N. the centre bears E. The second is: That in the Southern Hemisphere the bearing of the centre is always eight points to the left of the direction of the wind, as when the wind is N., the centre bears W.

Two other rules of equal importance should be remembered. The first is: In the right hand semicircle heave-to on the starboard tack. The second is: In the left hand semicircle heave to on the port tack—in both hemispheres.

It will then be seen that a ship laying-to in the right hand semicircle in the Northern Hemisphere, will be on the starboard tack, and heading off from the centre; and in the left hand semicircle, will be on the port tack, and with her head towards the centre. Also: In the Southern Hemisphere, a ship laying to in the right hand semicircle, will be on the starboard tack, but heading towards the centre; and when in the left hand semicircle will be in the port tack, but heading off from the centre.