ADDITIONAL OBSERVATIONS DURING STORMS. 33 



places, and by combining the facts obtained, that the meteorolo- 

 gist can be enabled to discover the laws which preside over these 

 great phenomena. For this, the three regular observations a day 

 are insufficient ; it is then earnestly recommended to observers, 

 who desire to contribute effectually to the solution of this great 

 problem, not to content themselves with the prescribed number, 

 but to add as many more as possible during the continuance of 

 remarkable storms j noting not only the state of the instruments 

 from hour to hour, if possible, but following with attention all 

 the meteorological changes. These observations must be entered 

 on the reverse of the sheet, under the head of Casual Phenomena, 

 which is particularly reserved for this purpose. 



The principal points to which attention should be directed are 

 the following : 



The barometer announces by a considerable fall the approach 

 of a storm. Then it begins to rise during its continuance, and 

 only resumes its nominal equilibrium after its close. Remark 

 especially the following points : 



Was the storm preceded by a noticeable or sudden rise previous 

 to the fall ; 



Note the state of the barometer, and the time when the fall 

 becomes more rapid ; 



Its state, and the time, when it is 4 lowest and when the rise 

 begins; 



The highest point which it reaches during, or immediately 

 after the storm. 



If alternations of rising and falling take place, the fact should 

 be mentioned and the time noted. 



The thermometer. The fluctuations of the thermometer in 

 the same time as those of the barometer should also be noted, 

 and their connection with the changes of the wind be observed. 



The wind. It is of the greatest importance to observe the 

 course of the winds through the entire height of the atmosphere 

 during the whole continuance of the storm, by means of the wind- 

 vane and of the clouds in the different layers of the atmosphere. 



The hour when the wind begins, and the direction whence it 

 comes ; 



The moment of its greatest violence ; 



The instant it changes its direction, and when it takes the di- 

 rection it keeps to the end of the storm. 



