The Rev. II. Lloyd on the Meteorology of Ireland. 413 



of the earth, and where so many causes are in operation, practical applications 

 can be obtained only from mature theoretical knowledge. Thus, it may be 

 shown that the knowledge of the phenomena of temperature, requisite for the 

 determination of the possible geographical limits of a single species of plants, ia 

 by no means inconsiderable ;* and when to this we add the consideration of the 

 other agencies which are at work in the atmosphere, all influencing vegetable 

 life, it is plain that we are not in a condition to deduce any useful result con- 

 nected with the distribution of species, until we have mastered a much larger 

 amount of theoretical knowledge than is usually brought to bear in such de- 

 ductions. 



It would seem, therefore, to be the duty of the Government of every civi- 

 lized state to provide the statistical data which have so many important 

 bearings upon the material welfare of the people, and in the form best fitted for 

 their discussion and examination. And to the lover of truth itself, for its own 

 sake, the fulfilment of this duty would, fortunately, supply the wants of science 

 in the most complete and satisfactory manner. 



In many countries, accordingly, provision has been made by their respec- 

 tive Governments for the collection and discussion of meteorological data upon 

 a unifoi'm and well-digested plan. The Government of Prussia appears to have 

 taken the lead in this important labour. Its example has been followed by 

 those of Russia, Austria, Bavaria, and Belgium ; and the names of Dove, 

 KuPFFEB, Kreil, Lamont, and Quetelet, to whom the superintendence of these 

 observations has been intrusted, afford the surest warrant of their successful 

 prosecution.! But perhaps the most important undertaking of this nature is 



* For each plant there is a lower limit of temperature, below which it will cease to vege- 

 tate ; while, in order that it may blossom and bear fruit, it must receive, between the two 

 seasons of this minimum temperature, a certain amount of heat beyond this limit which is con- 

 stant for each species. It is upon this integral of effective heat, as has been shown by De Candolle, 

 that the existence of the species depends. For information on this and other subjects connected 

 with the applications of meteorology, see the interesting introduction, by M. Martins, to the 

 Annuaire Meteorologique de la France. 



I The results of many of these series have been already published. Professor Dove has pub- 

 lished the results of the observations made in Prussia in the years 1848 and 1849. The observa- 

 tions made at the Russian observatories have been published from time to time by M. Kupfker, 

 in the Recueil des Observations faites dans VEmpire de Russie. The results of the Bavarian obscr- 



3 u 2 



