199 OBSEEVATIONS ON THE WINDS. 



constructed; it contains reductions of the whole 14, placed under each other 

 in the order of time. There it will be seen that the gale of the 30th of 

 January was South of Hahfax at 8 a.m., had advanced towards Newfound- 

 land by 6 p.m., and was half across the Atlantic by 8 a.m. of the 31st, 

 when it seemed to be lost in the normal area of low pressure over the centre 

 of the Atlantic. 



A similar gale appeared on the 2nd of February; it advanced to the 

 North-Eastward, and was lost by the 4th. On the 4th, a N.E. gale was 

 blowing on the American coast, and a moderate S.E. wind in 32^ N. and 

 51° W. Unfortunately there was a large space of sea in the South-Western 

 quarter of the chart without ships, so that we have not such clear evidence 

 of the progress of this gale ; still on the 5th we find a very heavy gale and 

 remarkable low pressure in the middle of the Atlantic, with a heavy N.E. 

 gale blowing in Iceland and on the American coast, and an equally heavy 

 S.W. gale in about 30° W. There are reductions of three charts for the 

 5th, viz., at 8 a.m., 3 p.m., and 8 p.m. These show the North-Easterly 

 progress of the area of lowest pressure. 



On the charts of the 6th and 7th, the direction of the wind indicates that 

 another area of low pressure was advancing from the South- Westward, 

 which showed itself to the South-Eastward of Newfoundland on the 8th. 

 On this last chart three areas of low pressure are shown, the last just 

 appearing on the South-Western corner of the chart ; this the extracts 

 prove to have been very severe, and to have advanced to the North-East- 

 ward, and it again was followed by another area of low pressure. 



The point of lowest pressure and complete eddy may be formed just 

 where the counter-currents of air are in close contact, and its apparent 

 motion may be caused by the closing in on each other of these currents of 

 air, by which means the eddy is being constantly re-formed at the new 

 point of contact. The chart of 8 a.m., February 5th, is supposed to illus- 

 trate this idea. 



If we consult Buchan's Isobars of Mean Pressure for these months, we 

 find that they trend to the North-Eastward from the Coast of America to 

 England, and that the prevailing wind follows them, drawing rather towards 

 the area of lowest pressure in the neighbourhood of Iceland. Hence, it 

 seems fair to suppose that the tracks of these occasional eddies may be 

 influenced by the main stream of air which seems to be flowing to the 

 North-Eastward round and into the area of lowest pressure, just as an 

 eddy in a river is carried along by the main stream. 



The data we have been dealing with prove that the points of lowest 

 pressure in these areas of low pressure do not generally cross the British 

 Islands ; for instance, at 8 p.m., February 5th, the barometer was down to 

 27-38 in about 51° N. and 25° W., and at 8 a.m. of the 6th it was 28-22 in 

 about 55° N. and 18° W., with a hurricane blowing from S.S.W. This 

 direction of the wind indicates that there was a lower pressure to the West- 

 ward, hence we may conclude that the area of loivest pressure took a very 

 Northerly course. Still, its influence was felt at all the self -registering 

 observatories, taking Valentia first, and passing on to Aberdeen. 



In tlie general remarks following the extracts for February 5th, we have 

 pointed out how the gale which Valentia experienced later in the day is 



