ATMOSPHERE OF GREAT BRITAIN AND ON THE CONTINENT. 



649 



short and covered the time of only two or three observations, but in some cases they 

 continued all day, and the highest and lowest numbers of particles are given for the 

 period during which the conditions remained fairly settled. From these highest and 

 lowest numbers the mean numbers were calculated. As the humidity varies a little 

 from time to time, the observations were entered in the table most nearly corresponding 

 to the average humidity of the observations. After all the observations had been arranged 

 into tables according to the wet-bulb depression at the time, the observations in each table 

 were then rearranged and put in the order of the number of particles, the observation 

 with the lowest number being put at the top of the column, all the others being put in 

 succession, ending with the highest number at the foot. All the observations as 

 rearranged will be found in Tables IX., X. and XL In these tables are given the dates 

 of the observations, the highest and lowest numbers observed, the mean number and the 

 maximum limit of visibility of the air in miles. If we now look down the column showing 

 the limit of visibility we shall see that the numbers in this column have also been put in 

 order, but the order is the reverse of that in the dust column. The highest limit of 

 visibility is at the top of the column, and the lowest at the foot. In other words, we see 



Table IX. — Shoiving the Relation between the Number of Dust Particles and the Transparency 

 of the Atmosphere at Kingairloch when the Wet-Bulb Depression was from 2° to 4°. 



Date. 



Lowest 

 Number. 



Highest 

 Number. 



Mean 

 Number. 



Limit of 



Visibility in 



Miles. 



C. 



1893. 

 22 nd June 



13th July 



21st „ 



10th „ 



84 



182 



329 



1250 



420 

 392 



588 

 2100 



252 



287 



458 



1675 



250 

 250 

 200 



50 



63,000 -| 

 71,750 1 Mean) 

 91,600 [77,525 

 83,750 J 



Table X. — Shoiving the Relation betioeen the Number of Dust Particles and the Transparency 

 of the Atmosphere at Kingairloch when the Wet-Bulb Depression was from 4° to 7°. 



Date. 



Lowest 

 Number. 



Highest 

 Number. 



Mean 

 Number. 



Limit of 



Visibility in 



Miles'. 



C. 



1893. 

 14th July 

 26th June 

 18th July 

 25fch June 



4th July 

 27th June 



2nd July 



85 

 336 

 483 

 109 

 635 

 1350 

 1600 



850 

 725 

 775 

 1375? 

 1050 

 1700 

 2400 



467 

 530 

 628 

 742? 

 842 

 1525 

 2000 



250 



250 



130 



200 



40 



50 



40 



116,750^ 



132,500 



81,640 



148,400 



(33,680) 



76,250 



80,000 



Mean, 

 r 105,923 



