St. Nicholas Magazine for Boys and Girls, Vol. 5, July 1878, No. 9 | Page 4

danger Of the barb'd hook, keen and small! Well she tries to warn her pupils Of all evils, low and high! But, alas! the vain young triflers Sometimes disobey--and die!
What was that which passed so quickly, With a slender shade behind? What is that which stirs the alders When no ripple tells of wind? What sends Mistress Salmo darting Underneath the stones in fear?-- Crying, "Hide yourselves, my darlings! Our worst enemy is near!" "I am bound to understand it," Says one self-proud speckle-side; "When I see the danger's real, Then, if need be, I can hide."
So he waits alone and watches, Sees the shadow pass again, Sees a fly drop on the water,-- Dashes at it, might and main. "Missed it! Well," he says, "I never! That's the worst jump made to-day! Here another comes--now for it!" Splash! He's in the air--to stay! When the alders cease to tremble, Silence comes and sun-glints shine, Mistress Salmo Fontinalis Calls the roll,--just thirty-nine!
[Footnote A: Brook-trout.]

[Illustration]
HOW THE WEATHER IS FORETOLD.
BY JAMES H. FLINT.
In former times, the chief herald of the weather was the almanac, which ambitiously prophesied a whole year of cold and heat, wet and dry, dividing up the kinds of weather quite impartially, if not always correctly.
But the almanac, good as it was now and then, and the weather-wise farmers, correct as sometimes they might have been, were not always able to impart exact information to the country; and they have been thrown quite into the shade of late, by one who is popularly known under the somewhat disrespectful title of "Old Prob," or "Old Probabilities." He has become the Herald of the Weather to the sailor, near the rocky, dangerous coasts; to the farmer, watching his crops, and waiting for good days to store them; to the traveler, anxious to pursue his journey under fair skies; and to the girls and boys who want to know, before they start to the woods for a picnic, what are the "probabilities" as to rain.
Every one who reads the daily paper is familiar with the "Weather Record," issued from the "War Department, office of the Chief Signal Officer," at Washington. These reports give, first, a general statement of what the weather has been, for the past twenty-four hours, all over the country, from Maine to California, and from the Lakes to the South Atlantic States; and then the "Probabilities," or "Indications," for the next twenty-four hours, over this same broad territory. The annual reports of the Chief Signal Officer show that in only comparatively few instances do these daily predictions fail of fulfillment.
The reason these prophecies are so true is a simple and yet a wonderful one. The weather itself tells the observer what it is going to do, some time in advance, and the telegraph sends the news all over the country, from the central signal office at Washington.
We shall see, presently, how the weather interprets itself to "Old Probabilities." Although it has proved such a fruitful subject of discourse in all ages, yet I am afraid many people who pass remarks upon it do not really think what the weather is made of. Let us examine its different elements.
The atmosphere has weight, just as water or any other fluid, although it seems to be perfectly bodiless. We must comprehend that the transparent, invisible air is pressing inward toward the center of the earth. This pressure varies according to the state of the weather, and the changes are indicated by an instrument called a barometer. Generally speaking, the falling of the mercury in the tube of the barometer indicates rain, and its rise heralds clear weather. Sometimes the rise is followed by cold winds, frost and ice. What these changes really indicate, however, can be determined only by comparing the barometric changes, at certain hours, in a number of places very far apart. This is done by the Signal Service. Observations are made at about one hundred and forty stations, in different portions of the country, at given hours, and the results are telegraphed at once to Washington, where our faithful "weather clerk" receives them, reasoning out from them the "probabilities" which he publishes three times in every twenty-four hours.
But the atmosphere varies not only in weight, but also in temperature. The thermometer tells us of such changes.
Besides this, the air contains a great amount of moisture, and it shows as much variation in this characteristic as in the others. For the purpose of making known the changes in the moisture of the atmosphere, an instrument has been invented called a "wet-bulb" thermometer.
We are thus enabled to ascertain the weight or pressure, the temperature, and the wetness of the air, and now it only remains for us to measure the force, and point out the direction, of the wind. This is