136 



NA TURE 



[Dec. 9, 1886 



it is therefore dangerous to lie-to in a typlioon, particularly 

 before you are sure that the centre is past. Vessels near the 

 coast of China, or in the Formosa Channel, generally seek 

 refuge in the nearest typhoon harbour indicated in the 

 Directory. 



The wind shifts faster the nearer the centre you are. If the 

 barometer falls rapidly and the wind does not change its direc- 

 tion, and when the gusts continue to increase in force, your ship 

 is in danger of entering into the central calm of the depression 

 with its mountainous and confused seas, which is by all means 

 to be avoided, as it is the high cross seas that do the most damage, 

 and not the force of the wind. When once you are caught in a 

 typhoon you should make no sail, except what may be necessary 

 to steady the ship, till the gusts continue to decrease in force and 

 the barometer has risen for some time. Very deceitful lulls are 

 reported to occur during the raging of a typhoon. The master 

 of a sailing-vessel is said to have put up topgallant sails after 

 getting into the central calm. Of course he could have had no 

 reliable barometer on board. 



In storms encountered in higher latitudes, where the incurva- 

 ture of the wind is not so great as in a tropical hurricane, the 

 right-hand semicircle is termed the dangerous semicircle, as a 

 ship running before the wind is in more danger of crossing the 

 path of the storm in front of the centre and perhaps be over- 

 taken by it ; but in a typhoon there is not much to choose between 

 the semicircles. A dismasted ship is in danger of being carried 

 into the centre from any quarter. 



However, the right-hand semicircle is also in a typhoon 

 generally more dangerous than the other, both with regard to 

 the risk of crossing the path in front of the centre, and also, as 

 remarked aliove, with regard to the force of the wind and con- 

 sequent greater sea disturbance. A ship experiencing a northerly 

 gale and a falling barometer in the China Sea in the typhoon 

 season is generally in greater danger than another experiencing 

 a south-westerly gale. 



When you have ascertained in which semicircle your vessel is 

 situated, you should, if in the right-hand semicircle, keep the 

 wind as long as possible on the starboard tack ; and if in the left- 

 hand semicircle, you should rim on the starboard tack, or heave- 

 to on the port tack, so as to let the ship come up as the wind 

 backs and run no risk of being taken aback. As explained furtlier 

 on, a typhoon encountered in a low latitude moves so slowly 

 that a steamer or fast sailing-ship has a fair chance of running; 

 away from it, but farther north, when the centre proceeds at the 

 rate of thirty or forty miles an hour, it requires careful manage- 

 ment even supposing you have ample sea-room. 



Typhoons are dangerous on the open sea, but they are still 

 more to be feared in open anchorages or near lee shores. Along 

 the south-west coast of Formosa and elsewhere, a ship must in 

 the south-west monsoon be prepared to run to sea at very short 

 notice, as in some of the harbours you could not lie with any 

 chance of riding out a typhoon. A steamer at anchor should get 

 up steam as soon as the wind rises abjve the force of a strong 

 breeze, and a sailing-vessel should take down the top-masts. 

 The direction in which the wind is going to shift must early be 

 determined so as to select a sheltered anchorage. If the centre 

 passes very near the anchorage, the berth may have to be changed 

 to the other shore during the lull, before the wind shifts to the 

 opposite quarter. 



A ship moored by a single anchor with her head to the wind, 

 will swing with the sun in the right-hand semicircle and against 

 the sun in the left-hand semicircle. If two anchors are dropped, 

 the anchor on the advancing bow should be let go first, there- 

 fore a ship in the right-hand semicircle of a typhoon should 

 first drop the port anchor and afterwards the starboard, in 

 order that she may ride with open hawse. And a ship in the 

 left-hand semicircle should first drop the starboard anchor. 

 But ships have to ride with a long scope in a typhoon, and as 

 they are liable to drag the anchors, some prefer to drop the second 

 anchor to veer upon if the first should not hold, 



II. The force of the wind and the appearance of the sky do 

 not always furnish a reliable guide to determine how far you are 

 from the centre of a typhoon. The dimensions are different in 

 different 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. Also the ii-point rule for ascertaining the bearing 

 of the centre fails near some shores if the centre is not near at 

 hand ; thus there often blows a steady easterly gale along the 

 southern coast of China when a typhoon is crossing the China 



Sea, and the gale blows often steady from north-east about the 

 northern entrance to the Formosa Channel when there is a 

 typhoon in a more southern latitude. 



The surest of all warnings is furnished by the standard 

 barometer on shore and the compensated aneroid on board ship ; 

 you are all right if you can put your vessel on the tack that will 

 keep your barometer rising. But in order to understand the 

 indications of the barometer you will have to keep a regular 

 meteorological register. The master of a vessel who does not 

 look at his aneroid till he is in a typhoon, does not derive half the 

 benefits from his observations that he wauld have enjoyed had he 

 watched it beforehand. He might perhaps have avoided the 

 weather he is now experiencing, or even have benefited by the 

 favourable winds and sailed round the typhoon. No doubt the 

 time is approaching when underwriters will stipulate that the 

 indications of an aneroid or a marine barometer must be regularly 

 registered on board a vessel insured by them. 



On the other hand, it would not be fair to ask the mariners to 

 keep complete meteorological records, such as are kept in the 

 lighthouses out here. Some seamen have a taste for this kind 

 of work and make very useful and fairly accurate observations, 

 but, for instance, the readings of dry and damp bulb thermo- 

 meters taken on many vessels are of very little use. 



The tube of the marine barometer has to be so much con- 

 tracted to stand the incessant pumping and danger of breakage, 

 that the instrument is sluggish and often reads half an inch or 

 more too high near the centre of a typhoon. Some cheap 

 wooden barometers cannot be registered below a certain height, 

 the cistern being too small to hold the mercury th.at comes out 

 of the tube. Of course some cheap aneroids are no better, and 

 even a first-class compensated instrument requires to be tho- 

 roughly verified, as the scale is never quite correct, but they act 

 nearly as quickly as first-class standard barometers, and for use 

 on board ship the instrument that is quickest in its indications 

 must be preferred. The objection to the use of the aneroid is 

 founded on the fact that its index-correction changes gradually ; 

 but then this can be determined and allowed for by reading it 

 off as often as the vessel enters a port, such as Hong Kong, 

 where correct meteorological observations are constantly being 

 made. 



The best hours for making observations are 4 a.m., 8 a.m., 

 &c., up to midnight inclusive. The observations should consist 

 in readings of the aneroid, temperature (this is no use except 

 when the thermometer is placed well forward so as to be exposed 

 to the wind, though in a position sheltered from the sun and the 

 rain), direction and force (0-12) of the wind, direction whence 

 coming of the clouds, amount (0-9) of sea-disturbance, and 

 weather (Beaufort's notation). For further particulars the " In- 

 ftructions for making Meteorological Observations, prepared 

 for use in China," published in 1SS3 by the writer, may be 

 consulted. 



From 4 a m. to 10 a.m. the barometer is rising, falling from 

 loa.m. to 4 p.m., rising from 4 p.m. to 10 p.m., and falling 

 from 10 p.m. to 4 a.m. It reads highest at 10 a.m. and lowest 

 at 4 p.m. During the approach of a typhoon this regular daily 

 variation may be masked, but it goes on all the same, and must 

 be taken into account when the barometer begins to fall before 

 a typhoon. Thus if it has fallen a certain amount between 

 10 a.m. and 4 p.m. you must subtract the normal descent be- 

 tween these hours in order to know how much of the fall is due 

 to the approach of the typhoon, and if it were between 4 p.m. 

 and 10 p.m. that it fell, you must add the normal rise for the 

 same purpose. 



In many typhoons, the barometer, reduced to 32° Fahrenheit, 

 and to sea-level, does not fall below 28 'So inches. In others it 

 falls as low as 28 '50. Lower readings of the barometer appear 

 to be rare, but it has been stated to have fallen much lower. The 

 rate at which your barometer is falling depends upon your 

 approach to the contre, and in consequence upon the rate at 

 which this is travelling. For this reason it is not safe to draw 

 conclusions concerning the amount of wind to be expected from 

 the rate at which the barometer is falling, but to some extent, 

 of course, this may be done. Remember, that, when the 

 barometer has fallen to its lowest reading and begins to rise, you 

 may expect to experience as much bad weather as you have 

 already gone through. 



The wind blows from a region where the barometric pressure 

 is higher, towards one where it is lower, being, however, deflected 

 towards the right in a typhoon, and the force of the wind 

 depends upon the difference of pressure between one place and 



