Ozone. 327 



Southerly and easterly tvinds being the point from which cm- 

 rain or snow generally comes, are for the most part present, dur- 

 ing the indications of ozone, while on the contrary northerly or 

 westerly winds, very rarely accompany its development. 



In reviewing these observations, there is no condition of the 

 atmosphere appreciable by our instruments, that indicates the pre- 

 sence of ozone except the presence of vapour or humidity. 



Schonbien has asserted that a high electrical state of the at- 

 mosphere was always present when ozone was developed, and that 

 •the amount depended essentially on the amount of atmospheric 

 electricity. From the comparison of nearly 6,000 observations 

 on the electrical state of the atmosphere, and the amount of ozone 

 taken at the same hour, at this place, and carefully compared ; I 

 have not found that opinion sustained, neither have I found its 

 amount or presence influenced by the appearance of the aurora 

 horealis which has also been said to be the case. 



From these observations it would appear that a moist and 

 humid atmosphere was necessary for the development of ozone, 

 and this may account in some measure for its more constant pre- 

 sence and its greater quantity, in proximity to the sea. So far 

 as its efi'ects on the production of disease in plants, especially the 

 potatoe, and to which it has been more especially referred ; it is al- 

 most certain that one of two causes must have given rise to the la- 

 mentable failure in this useful vegetable, either that the soil must 

 have furnished the medium of disease, or the action of the atmos- 

 phere upon the leaves and stem of the plant, — the causes which 

 act upon the stem and leaves, involve the action alone of Atmos- 

 pheric Influences, while those that act through the medium of the 

 soil are more numerous. 



In this neighbourhood the disease showed itself after rain fol- 

 lowed by a hot Sun, the atmosphere being loaded with moisture 

 or vapour — just the condition essentially proper for indicating the 

 presence of Ozone — the disease was ftiuch more extensive on wet 

 and clayey soils than on sandy or dry ones. 



It cannot be doubted that an agent so active as ozone, if really 

 present, must exert a great influence on the health of individuals as 

 well as animals and plants, the manner of its production, whether 

 by chemical action or electricity, or magnetism, demands from us 

 further investigation, and these investigations should be carried 

 out with uniformity for the sake of careful comparison — one point 

 should not be overlooked, that is, to mark carefully the amount 



