73 



instance of a storm that occurred at Liverpool on February 1st, 

 1868, Mr. Buchau records that " there were short intervals when 

 the velocity of the wind was at the rate of from 100 to 120 miles 

 an hour."* It is upon this velocity of the wind, " as it blows 

 round and in upon the centre of the storm, combined with the 

 onward movement," that the violence of a storm depends, and of 

 course its damaging effects. The onward movement itself, or the 

 rate at which the storm is impelled forward from place to place, is 

 very much less, varying from fifteen to thirty miles an hour, 

 though on rare occasions amounting to forty-five or more. It is, 

 moreover, "greatly retarded by friction against the earth's 

 surface." 



During the gale of October 14th-16th, 1877, the total 

 horizontal motion of the wind in twenty-four hours, as estimated 

 by the anemometer at Greenwich, amounted on the 16 th to very 

 nearly 600 miles. The maximum velocity was forty-four miles 

 per hour between 2 and 3 a.m. on the 15th. In some places it 

 was stated to have been much greater than this.t 



From the ckcular movement of these storms round a central 

 depression— the whole assuming more or less of a funnel-shaped 

 character — it follows that the revolving strata of air will be 

 successively at increased altitudes as the whorls recede from the 

 bottom towards the top of the funnel ; and the ascent from the 

 bottom will be more or less steep in proportion to the diameter of 

 the whole area occupied by the storm. It is important to know 

 the degree of this steepness, or to determine the gradients, as they 

 are called in the weather charts in the Times, the same being 

 ascertained by contemporaneous barometric observations at fixed 

 stations. The curved lines in those charts, dra-wn through 

 stations having the same barometric pressure, are called isobars' 

 and the gradients are more or less steep, according as those lines 



* " Handy Book of Meteorology," p. 259. 

 t " Symon's Met. Mag.," Nov. 1877, p. 147. 



