Here's a simple craft project that will appeal to younger children-a barometer without a needle, without mercury, and yet it really will indicate changes in the weather! The "working part" of the barometer is merely a piece of white blotting paper or cloth, which may be embodied in any design the child selects and mounted on cardboard or plywood. Immersion in the prepared solution will turn the cloth or blotting paper blue, and it will remain blue as long as the weather is dry; when the humidity rises it will become lavender in color, and red indicates rain or a storm.
The design might be a Dutch boy wearing a pair of blue breeches, a little girl in a blue dress, a boat sailing on blue waves, or the wise old owl (Figure 1). Anyone who protests that there's no such thing as a blue owl should be informed that this is a magic owl, and of course they can be any color!
The cloth or blotting paper is cut into pieces somewhat larger than the size needed for the design itself (this is to allow for possible shrinkage when the cloth is dipped in the chemical solution).
The solution is made as follows:
4 oz. water
1 oz. chloride of cobalt 1/2 oz. common salt 75 grains calcium chloride 1/4 oz. gum arabic
This will make about 40 cloth barometers, somewhat fewer if blotting paper is used, since the latter absorbs more of the solution.
The material for the "working part" of the barometer is immersed in this solution and allowed to dry thoroughly. The drying process may be hastened by putting the material in an oven, if one is available, or setting it out in the sun on a hot, dry day.
While it is drying, the children may be working on the remainder of the project.
The design is completed by cutting the other parts from paper of different colors and pasting or gluing them on a plaque of 3-ply wood or heavy cardboard. If necessary, the design may be traced from any picture the children choose, but it is far better to encourage originality, even at the expense of technical merit, and to encourage the children to create and develop their own designs.
When the material that was immersed in the solution is thoroughly dry, it is cut to the desired shape and size, and pasted or glued to the plaque. The mounting device is then added-a stiff cardboard or wood flap for an easel type of mounting if the barometer is to stand on a desk or table, a cord if it is to be hung.
In camp, where everyone is more or less weather conscious, this is an excellent "first-day" project. The craft counselor may have all the materials assembled so that the children can design and make barometers for their tents or cabins. If each unit has a name, such as Robin Hood, or there is a theme on which the program is based, the name or theme may suggest designs for the barometers.
A barometer would make a novel cover for a nature notebook. To make it doubly appropriate, the pieces of blotter may be cut into nature designs, such as leaves, vines or flowers, and arranged to form an attractive picture. This may be glued onto either a wooden or cardboard cover.
When there is to be a closing banquet, barometers would make attractive favors or place cards. They might take the form shown (Figure 2) in which the design is mounted on wood. Cut a branch of white birch or any wood with a smooth bark into pieces 3 or 4 inches long. Split them in two and mount on two smaller pieces of wood as illustrated, using a good glue or liquid cement. The calendar pad may be placed in any position that harmonizes with the design. Special days in the camp program may be indicated on the calendar by red circles or any special marking.