To launch a kite: run out about one hundred and fifty feet of the cord or wire while the kite is held by an assistant, who should give the kite a toss upward in the direction in which it must go. It is important that it be cast off directly in line with the wind. If the wind is light it may be necessary to run a short distance with a long line out in order to effect a launching.
Voluntary Weather Observers. There are more than three thousand voluntary or coöperating observers in the U. S. Weather Bureau. They receive no compensation other than the publications of the Bureau. They are required to read their instruments but once each day, as maximum and minimum thermometers record the highest and the lowest temperatures since they were last read and set. About sunset is the most satisfactory time for making the readings, since the thermometers will then show both the extremes for the past twenty-four hours. As a rule but one voluntary observer is accepted for a county. They are furnished without charge with maximum and minimum thermometers, instrument shelters and rain gauges, but not with wind vanes, anemometers for recording direction and velocity of wind, or barometers. But those who desire to become expert in forecasting the weather, as all may who study the chapter on forecasting, should equip themselves with an aneroid barometer, so that they may note the changes in the pressure of the air.
Fig. 5.—Comparison of the Thermometer Scales.
COMPARISON OF THERMOMETER SCALES
A little study of the accompanying information and diagram will enable any one to form a clear idea of the various thermometer scales and to convert temperatures from one scale to another.
Table of fixed points.
| Scale. | Temperature of melting ice. | Temperature of boiling water. | No. of degrees between melting ice and boiling water. |
|---|---|---|---|
| Centigrade | 0 | 100 | 100 |
| Reaumur | 0 | 80 | 80 |
| Fahrenheit | 32 | 212 | 180 |
Only Fahrenheit and Centigrade scales are in general use, and the accompanying plate is designed to enable observers to convert temperature readings from one scale to the other without resorting to a mathematical formula.