1889 - 90 .] 
Mr J. Aitken on Bust Particles. 
197 
on the beach, the second at 100 yards inland, and the third at 250 
yards from the beach. The wind at the time was directly inshore,' 
but it is possible it may have been polluted, as there are a few 
dwellings on the islands outside. Two observations were made on 
the beach at an interval of an hour and a half. The second 
observation gave twice the number observed in the first. This may 
have been due to many of the particles having been produced by 
the waves, and as the waves continued nearly the same, while the 
wind fell to about one-half, the number of particles of spray in the 
air would be increased at the time of the second observation. The 
increase, however, may have been due to pollution from the dwellings 
on the islands. At both the situations at a distance from the 
shore the number was less than on the beach. This may have 
been due to the air with the spray particles being diluted on its 
passage, through the woods, to the situations at a distance from the 
beach. 
The next town at which observations were made was Cannes. 
The position selected for testing the air of this district was the top 
of La Croix des Gardes, a small hill in the west bay, having an 
elevation of about 500 feet. The hill is situated quite outside the 
town, but it is surrounded on most sides by houses at no great 
distance. On the 10th of April, when there was a strong west 
wind, the air was very pure, there was only 1600 particles per c.c. 
rioted. The air on this day was likely to be as pure as it will ever 
be at this situation, as it came with a fresh wind direct over the 
Esterel Mountains, and from a very thinly populated district. 
The lowest number observed here was much less than the lowest at 
Hyeres, but at the latter place the wind on the days the tests were 
made never came from the least populated district, so that the 
observations taken at the two places do not admit of comparison. 
The observation taken at Cannes on the 12th show an entire change 
in the state of matters. The number on this day was very great, 
being as high as 150,000 per c.c. This was due to a change of 
wind, which blew direct from the town, and brought the products of 
combustion to the place of observation. 
On the 13th, observations were made on the sea air at Cannes. 
The wind was from the south, that is inshore, but it was light. 
These observations on sea air can only be made when there is little 
