These directions are very practically useful; they provide for geographical position--also for elevation above the sea--since they are not appended to any particular height of the column. They are suited to the northern hemisphere generally, as well as around the British Isles. The same directions are adapted to the southern hemisphere, by simply substituting for the letter N the letter S, reading south for north, and _vice versa_. South of the equator the cold winds come from the south; the warm, from the north. The S.E. wind in the southern hemisphere corresponds to the N.E. in the northern. The laws there are, while the wind veers from S.E. through E. to N. and N.W., the barometer falls and the thermometer rises. As the wind veers from N.W. through W. and S. to S.E., the barometer rises and the thermometer falls. =17. Instructions for the Sea-coast Barometer.=--The directions for fixing the barometer, and making it portable when it has to be removed, should be attended to carefully. The barometer should be suspended against a frame or piece of wood, so that light may be seen _through_ the tube. Otherwise a piece of paper, or a _white place_, should be behind the upper or _scale part_ of the _tube_. When suspended on a hook, or stout nail, apply the milled-head key (which will be found just below the scales) to the square brass pin at the lower end of the instrument, and turn _gently_ toward the left hand till the screw stops; then take off the key and replace it for use, near the scale, as it was before. The cistern bottom being thus _let down_, the mercury will sink to its proper level quickly. In removing this barometer it is necessary to _slope it gradually_, till the mercury is at the top of the tube, and then, with the instrument reversed, to screw up the cistern bottom, or bag, by the key, used _gently_, till it stops. It will then be portable, and may be carried with the _cistern_ end _upwards_, or lying flat; but it must not be jarred, or receive a concussion. =18. French Sea-coast Barometer.=--The French have imitated this form of barometer for coast service, and have translated Admiral FitzRoy's indications for the scale as follows:--