THE INTERNATIONAL WEATHER-SERVICE. 301 



other data for settling questions of climatology, and possibly of fore- 

 casting in some degree the character of coming seasons — are some of 

 the practical pi'oblems of every day's life which the international 

 charts and bulletins will serve to simplify or solve. Among these, 

 none perhaps calls for an earlier and exacter solution than the trans- 

 lation of cyclones from the Asiatic waters over the North Pacific 

 Ocean to the Pacific slopes of the United States, and the kindred 

 question of the transatlantic passage of American storms to western 

 Europe, As we have already seen, so far as critical examination has 

 been made of the Signal-Service weather-maps, more than one cyclone 

 from the Pacific coast every month, on an average, overleaps the 

 Rocky Mountains and travels eastward, reaching the Mississippi Val- 

 ley and the Lakes, with its original (perhaps ocean-born) strength. The 

 ocean is preeminently the birthplace and habitat of storms. Thence, 

 when fully formed and densely stored with aqueous vapor — the fuel 

 of the cyclonic engine — they assail the land-masses of the earth, and, 

 traversing them, unless in transitu, they pei'ish for want of water, and 

 return to their native element. This is no less true of the Great Ocean 

 that washes our Western shores, notwithstanding its name, than of 

 the " stormy Atlantic." Uncomfortably near as the West Indian hur- 

 ricanes ajsproach our Atlantic seaboard, they affect but comparatively 

 a small strip of the Eastern half of the United States, and often give 

 us a wide berth. But the storms which invade our Pacific seaboard, 

 from southern California to the mouth of the Columbia River, exert 

 or expend their full force within the national limits, and frequently 

 cut their broad swaths entirely across the country. The golden key, 

 therefore, to our continental meteorology is the adequate knowledge 

 of the barometric depressions and associate " waves of high pressure " 

 which roll over the continent from the westward, and, in their prog- 

 ress, dominate the weather to the north of the thirty-fifth parallel. 



Off the California coast there exists, throughout the year, a per- 

 manent area or wave of high atmospheric j^ressure, or a vast " anti-cy- 

 clone " — the diameter of which is something like one thousand miles. 

 The barometer in this area reads 30-20 inches (see chart, p. 309). From 

 its northern and western slopes, westei'ly and northwesterly wind-belts 

 extend in an easterly direction across the Coast and Rocky Mountain 

 ranges. The immense stationary anti-cyclone, from which flows off 

 this broad belt of westerly winds, is probably due to the continental 

 barrier an'esting and accumulating the perennial eqiiatorial current 

 from the central zone of the Pacific Ocean ; and has its counterpart in 

 the similar area of high pressure lying in the Atlantic, off the coast 

 of Spain and south of the Azores. The great '■^ highway^'' therefore, 

 along which the chief atmospheric currents move and introduce on our 

 continent the storm-controlling and weather-producing influences, be- 

 gins on the Pacific coast and traverses the country from west to east. 

 As the Atlantic dominates the weather of Europe lying on its eastern 



