Marvels of the Universe 903 
of Northern Africa, the Nor’-Wester of India, and the “ Arched” and Bull’s-eye squalls of the 
tropicalseas. The Féhn Wind is a hot, moist current of air which, after crossing the Swiss mountains, 
has some of its moisture condensed, and becomes compressed and hotter. 
The “ Sirocco” of Italy and Sicily is commonly described as a dry, hot wind, and the “ Har- 
mattan’’ of Western Africa, is an east wind blowing from the desert, carrying clouds of red dust 
far out into the Atlantic. The cold, often snow-bearing Winds of North America known as 
“ Blizzards,’ or sometimes as “ Barbers,’ are familiar by name to the newspaper reader, though the 
name has come to be popularly applied to any cold wind during the winter which is accompanied 
by driving rain, snow or sleet. The “ Nortes”’ of Mexico, the “ Bora”’ of the Adriatic, and the 
“ Mistral ’’ of Provence, are cold, northerly Winds, coming at the rear of cyclonic disturbances. 
Another series of Wind phenomena, the land and sea breezes, common on tropical islands, but not 
altogether unknown elsewhere, may also be briefly mentioned. The common explanation of these 
phenomena as due to the varied heating of the land and adjacent sea only partially accounts for 
the observed details of the circulation; but we must refer to the author’s “‘ Weather Science ”’ 
(pp. 158-9), for further particulars. By day the air over the land is heated and rises, its place 
being taken by cooler air from the sea ; we thus get the sea breeze ; by night, the action being reversed, 
the air near the ground flows outwards as the land breeze. On a low, flat coast such breezes are 
usually of slight force, but when there is a range of mountains not far from the sea the resulting 
winds are much stronger. Thus the sea breeze of Jamaica, owing to the proximity of the Blue 
Mountains, is often very powerful. 
The action of Wind as a geological factor now calls for our consideration. The surfaces of rocks 
are exposed to various agencies, and undergo the changes known by the general name of weathering. 
The rocks themselves, when not too hard, are worn down into fine particles by the action of frost, 
rain and running water, and this material is blown by the wind to lower levels or carried away 
A SHELL-BORING SPONGE. 
It is no uncommon thing to find oyster-shells pitted with holes made by this boring Sponge. Sometimes, as in this 
instance, the Sponge bursts the confines of the shell and develops externally into large cork-like masses. 
