4l4 
ART. IlI.—Some of the principal facts connected with the Phe- 
nomenon of the Helm Wind of Cross Fell in Cumberland. By 
CHARLES SLEE, Esq.* 
THE subject to which the following facts relate, though highly 
interesting, has received but little attention from the scientific 
world. I am therefore induced to make known the circumstances 
connected with it, as they have presented themselves to my own 
observation, in the hope of giving some information as to the pro- 
bable cause of the phenomenon. 
The term Cross Fell is applied to an extensive mountain range, 
of considerable elevation, being nearly 3000 feet above the level of 
the sea, and running in a direction which nearly coincides with the 
magnetic meridian. The outline of the chain, as seen from the 
west, presents but few inequalities, and may at that part where the 
Helm usually occurs, be considered as nearly horizontal. 
The western side rises somewhat abruptly, and is intersected in 
various directions by deep ravines. The eastern side, on the con< 
trary, forms a gradual slope of great extent. 
It often happens, but more especially in the months of March 
and November, that a current of air rushes dewn the western side 
of the mountain, with such immense velocity, that in many in- 
stances it has entirely carried away the roofs of the houses, and 
destroyed the crops of corn and potatoes situated near to the base 
of the hill. 
Its effects, however, are fortunately confined within very narrow 
limits, a cireumstance which forms the chief characteristic of the 
phenomenon. It seldom extends to a distance from the mountain 
greater than four or five miles; that is to say, the wind at this dis- 
tance is not higher than it was before the Helm commenced, and 
continues the same after its cessation. 
The most violent Helm which I ever witnessed occurred about 
five years ago, and during the whole time of its continuance, scarce- 
ly a breeze could be felt at the place where I reside, which is 
about eight miles west of the mountain. We could hear it dis- 
tinctly, and the sound which it occasioned strongly resembled dis- 
tant thunder. 
The Helm is invariably accompanied with a peculiar-locking 
cloud, which rests on the summit, and sometimes extends a consi- 
derable way down the side of the hill. It generally appears about 
an hour before the wind begins to blow,—remains perfectly quies- 
cent during its continuance,—and gradually disappears as the Helm 
abates. This cloud is called the Helm Bar; and it is that which 
* Read before the Royal Physical Society 20th Jan. 1830. 
