Limits of the Mean Temperature of Years, §fc. 3 



I repeat, that the readers of the Annuaire ought not to 

 expect to find here a complete investigation of the problem 

 which I have taken up. My sole intention is to lay before 

 them a few facts, which, taken in connection with those which 

 I shall analyse in a second notice, appear to me to lead to 

 this conclusion. 



Between what limits the mean temperatures of years and months 

 vary in our climates. 



The meteorological state of a given place, is much less 

 variable than those would be led to believe who judge of it 

 by their personal sensations, by vague recollections, or the 

 condition of the crops. Thus, at Paris, the mean tempera- 

 ture of years ranges witiiin very narrow limits. 



The annual mean temperature of Paris, from 1806 to 1826 

 inclusive, has been + 10°*8 centigrade (54°*4 Fahr.) The 

 greatest of 21 annual means does not exceed the general mean 

 by more than l°-3 (2°-3 F.) ; the lowest of the mean annual 

 temperatures has been found below the general mean only by 

 1°*4. (2°-5 F.) As far as relates to mean annual temperatures, 

 systematic meteorologists have, therefore, no need of foresight 

 to predict only slight perturbations. The causes of distur- 

 bance will satisfy all the phenomena, if they can produce, 

 more or less, l°-5 of centigrade variation (2°-7 F.) 



It is not the same with regard to the months. The differ- 

 ences between the general means and the partial means 

 extend, in January and December, to 4 and 5 centigrade 

 degrees (7° to 9° F.) 



drawing a few lines from his own resources. Vain efforts ! These pretended 

 Lectures on Astronomy at the Observatory have, however, reached no less than 

 a fourth edition. The laws have made no provision against what I shall call 

 this scientific calumny. What must be done when the law is silent ? Submit with 

 resignation ? A sensitiveness which will not appear surprising to any who have 

 seen the book in question, will not allow me to be satisfied with resignation. 

 My position having become intolerable, I have made up my mind to publish 

 myself the Lectures which have been so outrageously disfigured. Since it has 

 become necessary, I shall abandon for a time the plans for original investiga- 

 tions which I had formed, and devote the time I wished to employ in delicate 

 experiments, fitted to illustrate points of the science still enveloped in great 

 obscurity, to the preparation of a work intended to popularise astronomy. 

 May this work be in some degree useful. 



