THE BAROMETER AND THE WEATHER. 193 



is copied mechanically on a reduced scale on a slab on which 

 the outline chart has been already engraved. This engraving 

 completed, casts are made in fusible metal with the black lines 

 in relief, for printing with ordinary type, and the casts are set 

 up with the ordinary newspaper types, and printed with the 

 letter-press matter. 



The engravings overleaf are taken from two of the news- 

 paper weather charts for the dates of October 5th, and 6th. 

 They are enlarged and printed more clearly than the originals, 

 with an explanation of signs at foot of the charts. 



It will be observed that, in the chart for October 5th, an 

 isobar of 29 s runs up in a N. E. direction from between the 

 Orkney and Shetland islands, crosses the North Sea, strikes the 

 coast of Norway near Bergen, and then proceeds onward 

 toward Thron hjemd. An isobar of 29* 5 crosses Scotland, 

 following very nearly the line of the Grampians, enters the 

 North Sea about Aberdeen, and crosses to Christiansund ; 

 then runs up the Skagar Rack and Ghristiania Fiord toward 

 Ohristiania. Another isobar of 29*8 crosses Ireland through 

 Connaught to Dublin, onward across England by Liverpool 

 and the Humber, over the North Sea, and through Schleswig to 

 the Baltic. These three are nearly parallel ; but now we find 

 another isobar that of 30*2 taking quite a different course, 

 by starting from the Bay of Biscay about Nantes ; running on 

 toward Paris and Strasbourg, and then bending sharp round, 

 as though frightened by the Germans, and retreating to the 

 Gulf of Lyons by an opposite course to that on which it started. 

 On the following day all has changed ; the northern isobars are 

 running down south-eastward instead of north-east, and are 

 remarkably parallel. In the left-hand upper corner of this 

 chart is a note that " our west, north, and eastern coasts were 

 warned yesterday. 1 ' 1 Why was this ? It was mainly because the 

 barometric gradient or incline was so steep. On the 5th there 

 was one inch of difference between the Orkneys and the Bay 

 of Biscay, or between Bergen and Paris, while the barometer 

 was still falling in Norway and at the same moment rising in 

 Ireland and France. On the following day these movements 

 culminated in a gradient of 1*4 nearly one and a half inches 

 between Cornwall and the ancient capital of Norway. 



What must follow from this condition of the atmosphere ? 

 Clearly a great flow or rush of air from the south toward the 

 comparatively vacuous regions of the north. The gases of our 

 atmosphere, like the waters of the ocean, are always struggling 



