242 



THE AGRICULTURAL NEWS. 



August 3, 1912 



of the Bahamas, their movement has become northerly 

 and they continue to follow the curved path until in 

 high latitudes they are travelling in a north-easterly 

 direction, thus making their way, with much reduced 

 Strength, across the Atlantic Ocean. The actual origin 

 of storms arising during the hurricane season is in 

 a region in mid-ocean, ten to eleven degrees north of 

 the Equator. The rate of travel of a storm along its 

 course, that is its rate of translation, is ten to fifteen 

 miles an hour, in these latitudes. The velocity of the 

 wind in the spiral track, as far as it has been recorded 

 in the West Indies, is known to have reached 120 miles 

 an hour — a speed which means that the pressure of 

 the wind is more than seventy pounds on every square 

 inch of any flat surface that may be directly opposed to 

 it. As the wind is blowing in a circle around a centre 

 at which there is an njn'ush of air, this violence is not 

 shown at this centre, which is therefore a region of 

 calm — usually called the 'eye' of the cycloBe. 



In the former article dealing with the subject in 

 this journal, an account was given of the premonitory 

 symptoms of a hurricane, largely taken from the 

 United States Pilot Chart, and it will be convenient to 

 reproduce this here: — 



Before a hurricane, the barometer is some- 

 what higher than usual, with cool, very clear, 

 pleasant weather; there is a long low swell 

 from the direction of the distant storm; the 

 sky is covered with a quantity of light 

 feathery cirrus clouds (mare's tails) radiating 

 from a point on the horizon, where a whitish 

 arc indicates the bearing of the centre. If 

 the cirrus plumes are iaint and opalescent in 

 tint, fading gradually behind a slowly thick- 

 ening haze or veil, the approaching storm is 

 an old one, of large area. If of snowy white- 

 ness, projected jig^inst a clear blue sky, it is 

 a young cyclone of small area, but great 

 intensitj". Great activity of movement of the 

 upper clouds while the storm is still distant 

 indicates that the hurricane is of great 

 violence. 



As the storm approaches, the following 

 unmistakable sign's display themselves; the 

 barometer falls rapidly; halos are seen around 

 the sun and moon; the ocean swell increases: 

 the weather becomes hot, moist and oppressive. 



with light variable winds; deep-red and vinlet 

 tints apjjear at dawn and sunset, tints which 

 assume a coppery glare of ominous aspect; 

 a heavy mountainous cloudbank on the distant 

 horizon indicates the position of the approach- 

 ing storm; the bayometer falls more rapidly; 

 and finally, if the observations are made on or 

 near the storm track in the West Indies, the 

 wind begins to blow in a direction between the 

 north-east and north-west, soon rising to 

 hurricane force, increasing till the central calm 

 passes, then breaking out with violence from 

 the south to south-east. 



A knowledge of the nature and behaviour of 

 hurricane storms is ti the greatest importance to the 

 navigator, for it enables him to ascertain his position 

 in relation to the track that the storm will follow, and 

 to direct his course in such a way as to avoid the path 

 of the hurricane. In these latitudes, where the storm 

 moves along in an almost easterly direction, with the 

 wind blowing in a circle running from the north to the 

 west, from the west to the south, from the south to the 

 east, and from the east to the north again, it is evident 

 that the dangerous positions are situated in the 

 northern half of the storm, or dangerous semicircle as 

 it is called, for here the wind is from the east and 

 blowing toward the front of the storm. In the navi- 

 gable semicircle, or southern half, the direction of the 

 wind is from the west and toward the rear of the area 

 of the disturbance. These circumstances, too-ether 

 with the fact that in the West Indies, the track of 

 such storms is usually from the south-east to the 

 north-west, make the useful statement possible that, 

 on the occasion of a hurricane, as soon as the wind has 

 any point of south in it, the time of danger has 

 passed. 



Other indications useful to those encountering 

 hurricanes on land can be made from what has been 

 said. In any part of the storm area, if an observer faces 

 the vvind, the storm centre is on his right; and if the 

 direction of the wind remains constant, and there is an 

 increase in violence accompanied by a falling barometer, 

 it means that he is directly in the track of the hurri- 

 cane. His experience in such a case will be that these 

 latter conditions Avill be emphasized until the centre 

 or eye of the cyclone arrives, when there will be 

 a short calm, followed by a change of the wind to 

 exucily the opposite direction and a return of the 

 stormy conditions, usually with increased violence. 



