ATMOSPHERE OF GREAT BRITAIN" AND ON THE CONTINENT. 



625 



slopes or from the mountains. Observations made on two days have been omitted, owing 

 to no observations having been made at low level before going up the mountain. In 

 these two tables are entered the year and the day of the month when the observation 

 was taken ; and then in four columns are entered the number of particles at four 

 different levels — at low level, at 1000 feet, at 1500 feet, and at 2000 feet. When an 

 observation was not made at exactly any one of these elevations, it is entered under 

 the nearest figure in the table. The average number of particles at the different eleva- 

 tions is entered at the foot of the different tables. 



In Table IV. the mean number of particles at low level is 4857 per c.c, and falls to 

 4750 at 1000 feet, to 3430 at 1500 feet, and to 3125 at 2000 feet. In Table V. 

 the number at low level is almost the same as in Table IV., being 4743, but at 1000 feet 

 it falls to 3270. At 1500 feet it is only 2195, and falls as low as 1453 at 2000 feet. 

 The general conclusion pointed to by these two tables is that when the wind blew up the 

 mountain slopes the air at considerable elevations is not much purer than it is in the 



Table IV. — Showing the Number of Dust Particles in the Atmosphere at Different Elevations 

 on Monte Mottorone, ivhen the Wind was blowing up the Slopes. 



Date. 



At Low Level. 



At 1000 feet. At 1500 feet. 



At 2000 feet. 



14th May 1891 

 9th „ 1892 

 10th „ 

 13th „ „ 

 14th „ 



1st „ 1893 

 2nd „ 









6600 

 2500 

 6900 

 4100 

 4700 

 2800 

 6400 



4000 



4550 

 6700 

 3750 



2150 



4800 

 3400 

 2300 

 4500 



3100 

 3150 



Mean 



4857 



4750 



3430 



3125 



Table V. — Showing the Number of Dust Particles in the Atmosphere at Different Elevations 

 on Monte Mottorone, when the Wind did not blow up the Slopes. 



Date. 



At Low Level. 



At 1000 feet. 



At 1500 feet. 



At 2000 feet. 



11th May 1891 

 12th „ „ 

 13th „ „ 

 15th „ „ 

 11th „ 1892 

 29th April 1893 

 4th May „ 

 6th „ 











6400 

 3700 

 6700 

 4200 

 3550 

 3500 

 5100 

 4800 



2950 

 2900 

 3800 

 3200 

 3500 



2400 

 875 

 1850 

 2250 

 3600 



1900 



1350 



840 



1525 

 1650 



Mean 



4743 



3270 



2195 



1453 



