2i 4 DISSERTATION on the 



In this point of view, the fubject feems to me to merit in- 

 vestigation, fince the difcufiion of it is an object to fcience in 

 general, and to medicine in particular. The plan, then, that 

 I have chalked out to myfelf, as likely to throw light on the 

 fubjedt, is to give the Hiftory of the Northern Climate in one 

 paper, and that of its Phyfical Influence in another, as it ap- 

 pears in the new capital of Ruflia, St Peterfburg, where I have 

 refided for many years. Thefe two Differtations will contain a 

 number of facts and obfervations, from which Phyficians, in 

 the double fenfe of the word, may draw conclusions ; for I pre- 

 tend to nothing more than the honour of laying the foundation 

 of an important work to be profec-uted by others, and which 

 will probably require many years to complete. 



As to the execution of my plan : Firjl, I have made ufe of 

 the meteorological regifter, kept in the Imperial Academy of 

 Sciences, as fuch regifter muft be more clofely attended to than 

 that of any individual, whofe private bufinefs muft often call 

 him abroad at the proper hours of obfervation. 



2dfy, I have adopted the Academy's divifion of the year in- 

 to two feafons only, as in fact we have but two, properly fpeak- 

 ing, viz. winter and fummer, the one feafon running into the 

 other, without leaving well defined intermediate periods, to an- 

 fwer to what are called fpring and autumn in the temperate 

 climates. Nature appears to hurry in the north, by as quick a 

 tranfition as poffible, from the long fevere winter into its fhort 

 but ardent fummer ; fo that our thawing feafon occupies the 

 period of your fpring : and the fame kind parent feems to pro- 

 long the feafon of vegetation, from a fimilar wife intention, as 

 long as poflible, till furprifed in a manner at once by the re- 

 turn of winter, without much of what may be called autumn 

 weather. 



2>dly, I have followed the plan of the academic regifter, in 

 prefixing to each feafon an enumeration of the common pheno- 

 mena which take place in it, fuch as the quantity and duration 



of 



