48 
air, which is constantly tending to rise from the lowlands of Eden- 
side and the face of the Escarpment. The two strata—the colder 
and denser stratum, and the warmer and rarer, therefore meet 
along this line. An abrupt disturbance of equilibrium ensues. 
The heavier mass (or that which is most compressed, according to 
Mr. Atkinson) at once begins to flow to the lower level, rapidly 
increasing in velocity as it descends, until its rate of motion 
amounts to that of a gale. On reaching the lowlands its momentum 
causes it to rebound, and to rise some distance above the surface, 
where it resumes its initial direction and flows on until it reaches 
the zone where complete equilibrium is restored. As the direction’ 
of the Escarpment, and therefore of the zone where the wind is 
generated, is inclined thirty degrees or more to the direction of 
the east wind, a spiral movement is propagated. This may be 
better understood by tracing the course taken by any light body 
transported by the wind. Such a body would reach the ground at 
Milburn from a starting place on Dufton Fell, it would travel from 
Milburn outwards to Blencarn, thence, rising in the air it would be 
carried over Ousby by the spiral current and then again to the 
low ground, say at Melmerby. 
The locus of strongest impact of the Helm Wind must vary 
greatly according to local circumstances. Usually it would sweep 
down directly upon the fell sides and expend its force before 
reaching the lowland area adjoining. But as there are necessarily 
considerable variations in both the direction and the force of the 
generating currents of air, the. zone where the wind strikes the 
ground with greatest force must vary accordingly. This enables 
us to account for the curious fact that sometimes the Helm Wind 
is blowing violently on the lower part of the fells, while a mile or 
two outward in the direction of the lowlands a comparative calm 
prevails ; or, on the other hand, that a strong wind may be blowing 
along a zone parallel to the fells while there is almost no wind at 
all on the slopes adjoining. 
The Helm Bar does not call for any special remark, as the 
mode of formation of any such apparently-stationary masses of 
visible moisture is already well known. 
[It is right to mention that this paper is based upon the paragraph on the 
“*Helm Wind” given in my ange “Westmorland” in the latest edition of the 
Lncyclopedia Britannica,—J. G 
