571 



the least impulse, if time be given, but presents gi'eat resist- 

 ance to any rapid movement. The two reduce the excursions 

 three-fourths. But he thought it would not be desirable to 

 remove them entii'ely, even if possible, because he has found 

 that this is a distinctive character of some winds, independent 

 of their force. It is always connected Avith a tempestuous 

 roar, which gives an exaggerated impression of their force ; 

 and some of the heaviest gales he has observed were compa- 

 ratively noiseless. He then showed three of the sets of dia- 

 grams; one, of April 18th, the day of the stonn Avhich did 

 such damage in Dublin, had nothing remarkable, except that 

 from 3 to 5 there was a great change of direction to the 

 eastward, and return to the original point, with a sort of un- 

 steadiness that seemed to mark some struggle. The second 

 was a gale on December 15, 1848, in which 516 miles in 

 twelve hours were recorded. In the hour from 2 to 3, 

 gixty-one miles were passed ; and during two minutes and a 

 half of it the velocity was at the rate of 105 i miles per hour. 

 This was a cyclone, or circular storm. But a still finer speci- 

 men of that was afforded by the third, in wliich 380 miles in 

 twelve hom-s was marked, but the direction changed nearly 

 through two entire cii-cumferences. 



He should have detailed the mode of combining the re- 

 sults thus obtained ; but he felt he had already trespassed too 

 long on their patience. He thanked the Academy for theu- 

 indidgence, but referred it to the interest which they took in 

 whatever tended to advance physical inquuy. He did not 

 fear to be met by any body guided by such a President, much 

 less by the Royal Irish Academy, with the utilitarian question, 

 " Of what use is all this ? " " Even on that ground we might 

 encounter an objection. If, as in the case of the tides, we 

 succeed in working out a theory of the winds, it would have 

 a high commercial value. And why not ? We know many 

 of their causes, the temperature, the vapour, tension, the 

 electricity of the atmosphere. We want only the anemome- 



