I have said that the barometer has no fair weather standard--the mean of 30 inches at the level of the sea being an _average_ of the _fair weather_ elevations and the _foul weather_ depressions. Its fair weather position, it would seem, must be above the mean, therefore, and as much above as its foul weather depressions are below. But this is not precisely true. Its extreme fair weather range is 31 inches, and it rarely reaches that; while its lowest storm range is down to 28, and is the most often reached of the two. My barometer stands about 40 feet above ordinary high-water mark. It is not a "wheel," but an open, "scale" barometer, and a perfectly good one. Its most reliable fair weather standard is about 30-30/100 inches. It is its _most common summer, set fair position_, but that position is often at other and different elevations, at other periods of the year, during fair weather. The reader must observe for his own locality, and satisfy himself what the most common set fair position for the barometer is, at the different periods of the year, where he resides. When he has ascertained this, he may apply the following principles to illustrate its exceptional action, and in judging of the future of the weather: 1st. _As to its rise before storms._--Supposing it to have been stationary, at or about a set fair position, _for the period_, and for one or two or more days, a very _gradual_ and _moderate_ rise is an indication of continued fair weather; and a _sudden_ and _considerable rise_ is indicative of a storm. If the sudden and considerable rise occurs in the latter part of spring, summer, or early autumn, it indicates a storm of the _first_ or _third classes_ described in Chapter X., if in winter, a storm of the _first class_ only. If the elevation is _very_ sudden and considerable, the storm will probably be _severe_. The philosophy of this, according to my present apprehension of it, is, that these storms present an _extended easterly front_--_settle very near the earth_--and _have a rapid progress_--thus accumulating the atmosphere somewhat, in advance of them. 2d. _As to its fall before storms without previous rise._--This is always very regular before the second class of storms, or polar belts of showers and storms. It is very fairly exemplified in the table from Reid, on page 329. The barometer, so far as I have opportunity to observe, does not rise from a stationary position on the approach of this class of storms. At the commencement of heated, summer, dry terms, my barometer has most frequently ranged at about 30.30, and gradually, but slowly, fallen below 30 inches before the belt of showers arrived, and the term closed. The fourth rule of Dalton (Meteorology, page 183) indicates a similar law in England. It is as follows: