128 



The Wind and its Direction. 



w 



w 



1 



J^c^* 





E 



1 

 1 

 l 





"■^~~ 









^Ts 











V 











r 



F!C: 3. 



half an hour, another change at 10 a.m. to SSW., and back 



again, after which the wind oscillated gently on WSW. 



In Fig. 3 (January 23rd, 

 18C-1) we have an example of 

 an oscillating wind, which 

 was violent at first on S. 

 (the oscillations reaching 

 from SW. to ESE.), then 

 SSW. (the oscillations ex- 

 tending from W to SSE); 

 at 5*20 a.m. suddenly veer- 

 ing to WNW. (with small 

 oscillations) and then to 

 WSW. In this diagram a 

 gale of wind occurred, and 

 the manner of registration 

 is shown in Fig\ 3, the line 

 being the zero pencil 

 line of a calm, and A, B, C 

 the registration of the wind's 

 force on the square foot, the 



greatest violence of the gale occurring at B, when 71b. was 



registered. 



The value of such a series of registration is great, and 



especially so since Mr. James Glai- 



sher has shown that a wind law 



exists, a law of movement in which 



in some years the direct movements 

 d the retrograde; whilst in 



other years the retrograde move- 

 ments predominate, i.e. when direct, 



working forward like- the hands of 



a watch, and when retrograde, mov- 

 ing in the opposite direction. 



The contrivance is so simple 



that it cannot get out of order, 

 isting of a simple brass rod, to 



the upper end of which a wind vane 



is attached, whilst at the base a 



pencil on a short arm records all 



bhe movements as the rod Itself 



barns round, Fig. 4. This brass rod 



is taken advantage of for the wind's 



force; being hollow, a wooden rod 



• stends i trough it, attached to a 



force board on the vane; whilst 



immediately above the registration table a cradle is suspended, 



fig:4-. 



