WHAT CONSTELLATIONS ARE VISIBLE THIS

MONTH? (XXI-1)

The problem. Most people notice that the stars are grouped so that they form more or less conspicuous figures. The Big Dipper and the North Star are easily located. The Dipper is part of a larger group of stars called the Great Bear. Some of the larger stars in the more prominent constellations are easily located after they have once been pointed out to the observer. What conspicuous groups are visible now?

What to use. The sky map which is printed each month in the Monthly Evening Sky Map or the first issue of the month of the Scientific American will be the most convenient. A "star finder can be used in the laboratory. Most pupils will find it wise to carry a small sky map so that observations can be made on any clear evening. A flashlight is useful for studying the map at night.

What to do. 1. Secure the sky map for this month and mark on it the groups of stars that are to be located. Any of the important constellations mentioned in sections 275 to 278 of the text may be selected. If each pupil is not provided with a map, a large drawing should be placed on the blackboard, so that each pupil may copy it for out-of-door use.

2. Observe the sky each clear night until you have located the chief constellations. Do not try to locate too many groups the first few evenings. Do not be discouraged if you have trouble in making the map fit the sky. It is difficult to represent a hemisphere on a flat surface. Make a record of the observations.

Questions. Which constellations are most prominent? Locate the brilliant stars in these constellations. Do these stars rise and set as the sun? Do all the stars have the same color? the same size? Do you know the names of any of these stars? Does the Dipper move from hour to hour?

Suggestions for report. Make drawings of two important constellations as a part of the notebook record. Locate the groups on a figure similar to figure 39.

Reference work. Read Chapter XXI.

Optional problems. On a clear and moonless night focus a camera on the North Star. Expose the plate or film for three or four hours. Develop the negative and account for the curved lines on the picture. Make an observation of the Big Dipper every two hours during the entire night and keep a record of the observations. Explain the change.

HOW ARE SOILS FORMED? (XXII-1)

The problem. It is thought that the earth's surface at one time was all rock or water and that fertile soil is of relatively recent origin. Almost all land regions and many water regions give some evidence of the ways in which soils are formed. A study of such regions to determine what is occurring will usually yield valuable information.

What to use. The local stream beds and banks, hillsides, surface drains, exposed rocks with vegetation attempting to grow upon them, soil-survey reports bearing upon local soils, discussions of soils in library books and magazines.

What to do. 1. An excursion should be made into the adjacent country to study the soils. River-bottom lands, uplands, banks of streams, and walls of open ditches

FIG. 40. Plant action in soil-making Upper picture, lichens destroying rock; midshould furnish contrasting dle picture, a tree splitting a rock; lower

types of soils. Differences

in crops and in natural vegetation in correspondence with soil differences should also be observed. Visit a rocky ridge or ravine and study the formation of soil by weathering and plant action (Fig. 40). If the region is within a glaciated area, look for evidences of glaciation and formation of glacial soils (Figs. 139 and 140 in the text).

2. Find whether the region about the school has been surveyed by the Bureau of Soils, Department of Agriculture, Washington, D. C., and if so, secure a copy of the report. This will give maps and details regarding soil types of the region. The details of this study will vary with the locality.

Questions. Are there local areas of exposed rock in which you can find evidences of its disorganization to form soil? What effects do plants have in soil-making in rocky regions? Is there any evidence of glacial action? Does your community contain any glacially deposited soil and rock? Which type of soil in your community is considered most valuable? Why?

Suggestions for report. Write a brief history of the formation of the soil of your locality, giving specific local examples.

Reference work. Read sections 280 to 287.

Optional problems. How many types of soils are there in your locality? Can you determine the causes of the differences in these soils?