129 - 



v<:dro of water thrown into a red-hot boiler in a steam- 

 ship or steam factory is ,,suf ficient to blow either structure 

 to pieces. For this reason the utmost care is exercised 

 in the use of steam-boilers to prevent the complete eva- 

 poration of moisture, as the accidents resulting from 

 neglect of caution in this matter are disastrous and dan- 

 gerous in the highest degree, resulting often in serious 

 loss of life and property. 



Now let us observe what takes place on the surface 

 of the earth itself after the passage of a thunder cloud. 

 We saw that the earth suffers at such times from an 

 absence of moisture, while the oxygen continuing to 

 appear in fresh quantities begins to burn up vegetation. 

 The drops of water falling in rain upon the earth yield 

 their much needed moisture to the ground, and the roots 

 of plants labour to raise this moisture and circulate it 

 through the stems and foliage. The oxygen eagerly unites 

 with the desired element of hydrogen in a new form of 

 combination O:$, called in the language of chemistry 

 ozone. Instead of the simple combination of hydrogen with 

 oxygen, we see here a combination of hydrogen with 

 oxyde of oxygen, a phenomenon only observable after 

 thunder-storms. At such times the air is fresh and 

 light. 



Whoever follows the barometrical charts in the news- 

 papers will certainly remark that the raised and depres- 

 sed points on the surface of the earth's atmosphere are 

 very numerous, and that the warmer a country the more 

 frequent these points. Though we have no published 

 particulars of maximums and minimums under the tropics 

 and near the equator, there is no doubt, judging from 

 analogy but that they are more frequent there than in 

 our northern parts. Here a chain of consequences ensues. 

 The more frequent these barometrical points the more 

 pronounced the atmospherical incline; the more pronoun- 

 ced the atmospherical incline the swifter the descent 

 thereby; the swifter the movement of the azote the 

 stronger the atmospherical winds. Sometimes two cur- 



9 



