I should like to describe the instruments fully, but must content myself with telling you what remarkable things some of them do. The self-registering barometer, for instance, is made to actually photograph a storm; another is made to draw with a pencil, every hour, figures that show the height of the column of mercury and the condition of the atmosphere. Even the vane, or weather-cock, marks down the direction and force of the wind.
The report of the chief signal officer for the year 1876 gives some idea of the vast amount of labor performed by the service. The Herald of the Weather never rests. As he says, "The duties of this office permit little rest and less hesitation. Its action must be prompt. * * * Its orders must issue, its signals of warning be given, and its record thus made, sometimes when wisdom would delay, if possible, and subsequent information show it had delayed rightly. It is the simple duty of the office to act at each present moment as well as it can with the information at that time before it. The reports to come after can only give bases for future action, while exhibiting the right and wrong of the past." These points should be borne in mind by those who are disposed to find fault with some of the daily predictions about the weather. If these predictions do not always come true, it is for the reason given above. Each report must be made at a given hour. Sudden changes may occur immediately after a report has been issued. These changes cannot be waited for, and cannot always be foreseen. But the general accuracy of the daily reports cannot be questioned, as about eighty per cent of their predictions are known to have been verified, and the average of failure grows less.
The method of arranging, comparing, and studying out the meaning of all the different records of observations made at all the weather stations, cannot be explained in a short article. But I may add that the weather is, after all, not quite so capricious as its accusers have asserted. And it has been found that all storms have certain "habits, movements, and tracks." It is by applying these laws, and drawing conclusions from them, that the prophet of the weather is able to tell so nearly what kind of a day we shall have, and just about where and when the storm will come.