OF THE BAROMETER AT MANCHESTER. 267 



periods, of course somewhat interferes with the exact com- 

 parison. 



Table III. contains the fall of rain for each month com- 

 pared with my own average for twelve years and Dr. 

 Dalton's average for forty-seven years. 



Table IV. contains the mean monthly temperatures and 

 their difference from the twelve years' average. It is much 

 to be regretted that we have no trustworthy observations 

 of the temperature for as long a period as that of the fall 

 of rain, as differences from a longer average would have 

 been of more value for this part of the investigation. 



Having obtained the values of the oscillations, it was 

 thought desirable to determine what connection there 

 might be between the amount of oscillation and the fall of 

 rain ; also the relation, if any, existing between the mean 

 temperature and the amount of oscillation. 



In Table V. the falls of rain above the average are com- 

 pared with the corresponding amounts of oscillation, and 

 the falls of rain below the average with their corresponding 

 oscillations. This table shows that a fall of rain in excess 

 of the average, is attended by a considerable increase in 

 the amount of the oscillations in every month but October ; 

 and it is very probable that this month would agree with 

 the others, if taken from a longer series of observations. 



In Table VI. similar data are given for the mean tem- 

 peratures of each month, according as they are above or 

 below the average. 



In this case we find that in February, April, May, June, 

 July, October and December, a temperature below the 

 mean for the month increases the amount of the oscilla- 

 tions, whilst in the remaining months of January, March, 

 August, September and November the converse would 

 appear to hold good. 



In Table VII. the numbers of oscillations above or below 

 the average are compared with the corresponding falls of 



