58 The Ottawa Naturalist. [June 



the country, as it were, actually before his eye, instead of the flat 

 map on which the data are charted. 



The official may know and predict accurately the general 

 direction in which a storm will move, and yet in thickly popu- 

 lated parts, as western Ontario, the passage of a storm only 

 twenty miles to the northward or the southward of the point 

 fixed in advance by the forecaster will result in weather con- 

 ditions which must disappoint thousands of people who are 

 interested therein. The narrow difference of a few miles in 

 predicting twenty-four hours in advance the path of a storm which 

 travels 600 or 700 miles daily is almost infinitesimal as regards 

 the storm itself, and yet it is sufficient to produce cold northerly 

 • winds, with snow, in place of warm southerly winds, with rain, 

 or vice versa. 



The introduction of the telegraph made it possible to collect 

 meteorological data from a large section of country in time to 

 make it of use in following the weather changes over a whole 

 region at the time the events are actually taking place, and also 

 to transmit storm warnings in advance of the approach of a 

 storm. The telegraph is to the meteorologist what the telescope 

 is to the astronomer. Thus we follow the movement of cyclones 

 and anti-cyclones and their accompanying weather conditions 

 across the country in much the same manner that we can follow 

 the movements of a railroad train if we know its time and place 

 of starting, and its route and speed. But the cyclones or storms 

 vary so much in intensity, in the paths which they take, and in 

 their velocity of movement, that their positions and conditions can 

 usually be foretold only day by day. Once having fixed the 

 position of a cyclone or anti-cyclone with regard to any place, 

 we know the general weather conditions at that place as shown 

 by the distribution of the meteorological elements in cyclones 



and anti-cyclones. 



The daily weather maps are prepared in the following 



