=143. Distribution and Effects of Ozone.=--Mr. Glaisher has found that "the amount of ozone at stations of low elevation is small; at stations of high elevation, it is almost always present; and at other and intermediate stations, it is generally so. The presence and amount of ozone would seem to be graduated by the elevation, and to increase from the lowest to the highest ground. The amount of ozone is less in towns than in the open country at the same elevation; and less at inland than at sea-side stations." It seems to abound most with winds from the sea, and to be most prevalent where the air is considered the purest and most salubrious. This may seem, says Admiral FitzRoy, in _The Weather Book_, to point to a connection between ozone and chlorine gas, which is in and over sea-water, and which _must_ be brought by any wind that blows from the sea. It prevails more over the ocean and near it than over land, especially land remote from the sea; and, says the Admiral, it affects the gastric juice, improves digestion, and has a tanning effect. Dr. Daubeny, in his _Lectures on Climate_, writes: "Its presence must have a sensible influence upon the purity of the air, by removing from it foetid and injurious organic effluvia. It is also quite possible that ozone may play an important part in regulating the functions of the vegetable kingdom likewise; and although it would be premature at present to speculate upon its specific office, yet, for this reason alone, it may be well to note the fact of its frequency, in conjunction with the different phases which vegetation assumes, persuaded that no principle can be generally diffused throughout nature, as appears to be the case, with this, without having some important and appropriate use assigned for it to fulfil." =144. Registering Ozonometer.=--Dr. E. Lancaster has contrived an ozonometer, the object of which is to secure the constant registration of ozone, so that the varying quantities present in the atmosphere may be detected and registered. For this purpose, an inch of ozone paper passes in each hour, by clock-work, beneath an opening in the cover of the instrument. CHAPTER XVI. INSTRUMENTS NOT DESCRIBED IN THE PRECEDING CHAPTERS.