148 Mr Harvey on an ifiteresting Meteor ologieal Phenomenon. 



Art.. XXI II— On an interesting Meteoi'ologkal Phenomenon. 

 By George Harvey, Esq. F. R. S. Lond. and Edin. Mem- 

 ber of the Royal Geological Society of Cornwall, &c. &c. 

 Communicated by the Author. 



X HE formation of a cloud of the cirro-cumulus kind, at the 

 extremity of a cape or headland, rolling forward from a point 

 of origin successive masses of dense and visible vapour, so as 

 to create the appearance of an interminable moving cloud, has 

 no doubt often attracted the attention of your meteorological 

 readers ; but as peculiar localities sometimes occasion diversi- 

 ties of appearance worthy of being recorded, I have forwarded 

 for your inspection the inclosed sketch. (Plate I. Fig. 4.) 



The entrance of Plymouth Sound is situated between two 

 moderately elevated portions of land, that to the right of the 

 drawing in the distance being Penleepoint, and the nearer land, 

 covered with beautiful groves. Mount Edgecumbe ; the land on 

 the left or eastern side being Staddon Heights ; the dark line 

 in the sea between the hills representing that great monument 

 of skill, the Plymouth breakwater. About noon, on the 11th 

 May, a cirro-cumulus, of a very dense and definite character, 

 was perceived to come from the verge of the western horizon 

 with a moderate velocity, and after passing at a small elevation 

 above the woody summit of Mount Edgecumbe, vanished in 

 the pure and cloudless air over the tower on the distant pro- 

 montory of Penlee. The moving mass formed a continuous 

 cloud, accommodating itself to all the changes and inequalities 

 of the land. Over the sea, however, not a cloud was to be 

 seen ; but on the eastern side, nearly over the flag-staff, the 

 cloud was perceived to form again, and with a steady and uni- 

 form velocity to roll its volumes at nearly the same elevation 

 above the land, until it was again lost in the farthest verge of 

 the eastern sky. From the west, therefore, there continued 

 incessantly to come forth large and visible volumes of cloud, 

 which became dissolved in the air just where the sea began to 

 exercise its influence upon them ; and where the water lost 

 its power, just above the flag- staff, the vapour became again 

 condensed, so that over the sea, between the well-defined ex- 



