LECTURES. 59 



Wind has been called the vehicle of climate, it is caused by the 

 flow of air from a region of higher to a region of lower pressure. In 

 this country there are two main currents of very different types. The 

 first reaches us from the Atlantic and is laden with moisture. It is 

 cool in Summer and warm in Winter. The other comes over the 

 Continent and is therefore much drier, making Summer hotter and 

 Winter colder when it occurs in these seasons. Fortunately these 

 Easterly currents are comparatively infrequent, for, whereas, the 

 average number of days in a year when the wind is S.W. is 106, that 

 when the wind is N.E. is only 45, while East winds only occur 

 on 27 days, West winds occurring on 46 days, so that we get 

 many more winds from the Atlantic than we do from the 

 Continent. Wind is very beneficial to the growth of trees, for the 

 movement it engenders in them causes the sap to flow more freely, 

 and it is also of course a great purifier of the atmosphere. That 

 mysterious ingredient, ozone, is always more prevalent in windy 

 weather, and it is generally held to have very purifying and health- 

 giving qualities. Not only is the direction of the wind taken at all 

 meteorological stations, but at many its force and velocity are mea- 

 sured. This is done by an instrument — an anemometer — consisting 

 of four cups mounted on a pole attached to an index and dial below. 

 By means of these instruments the daily and hourly velocity of the wind 

 may be measured. It is unfortunate, however, that there is a lack of 

 uniformity in the scales used with these instruments, and you conse- 

 quently often get figures quoted in different places which it is exceed- 

 ingly difficult to harmonise. Beaufort's scale, which puts the velocity 

 of a calm at three miles per hour, and that of a hurricane at 105 is now 

 generally considered too high. During the recent storm on the 12th 

 of January, you doubtless observed, recorded in the newspapers, 

 velocities of 70, 80, and 90 miles. But when we consider that the 

 greatest velocity recorded in the great hurricane in the West Indies 

 before the instruments were blown away was 62 miles an hour for 5 

 minutes and 75 for one minute, there would seem to be something 

 wrong with the English records. It is estimated that the wind did 

 attain 90 to 100 miles per hour in the West Indies during the hurri- 

 cane and we know with what results. No such results occurred in 

 England and yet the velocity is made to be the same. In consider- 

 ing the velocity of the wind during a storm this of course is not the 

 velocity of the storm. While the velocity of the wind may be from 

 30 to 60 miles per hour the storm itself may not be moving at a 

 greater pace than 8 or 10. The rates at which cyclonic storms travel 



