PREFACE. 



For tlie last fifteen years I liave liusied myself, particularly during the summers 

 witli the examination of niglit-frosts and the means of preventing their ravages. The 

 first time was spent in preparatoiy studies. This phenomenon, so alarming in its effects, 

 has been brought imder general natural laws. Dming thèse studies my own opinion on 

 the phenomenon has gi-adually ripened and lieeu consolidated, particularly what concerns 

 the autumn frosts. The work has, however, often suffered a shorter or longer inter- 

 ruption, caused by some casual occurrence. 



In 1886 a preliminary society was formed, its object being to work for spreading 

 the knowledge of „frost-torches" and the proper way of applyiug them. This society 

 appointed a Committee consistmg of Herr CI. Strömberg, Herr W. Brummer, and the 

 nndersigned. To thèse gentlemen I am gi-eatly indebted for their kindness, for which 

 I hereby beg to render them my gïateful thanks. An account of the Committee's work 

 is given in a special publication, from which much information may be gathered. 



Many friends liave kindly aided me in this work, and it is both pleasant and just 

 that I should ott'er them my liest thanks. 



THE AUTHOR. 



