Another important medium of visual education is the moving picture. Here we have many of the advantages of the still projector and the added advantage of having the objects moving. These are best for wild life pictures, advertising guide trips, etc. There is no special advantage in using them for simply scening showings. In all probability the, moving picture will replace the still within a few years in our lecture work, but at present we have no skilled photographers available and I feel that our efforts should be concentrated on the still projection.
There are many other mechanical devices to aid a lecturer. Just as the hand specimens augment museum display, so do hand specimens augment a lecture. In a tree lecture it is much more instructive to have the cones and leaves of the tree at hand than simply to tell about them. In explaining obsidian, for example, it is a simple matter to pass a small piece around the group, providing it is a medium sized audience. Another method which I have seen worked with great success is a display table. Here the lecturer has many of the objects upon which he is lecturing. He is not only able to show the audience the real thing but they are priviledged at the end of the talk to come forward and examine them at their leisure. One of the best methods of lecturing to a small group, at least, is the time-honored “chalk talk.” It is a simple matter to rig up a blackboard. Chalk is cheap and provides a medium that will go far in putting over the story.
In summing up the mechanical methods to augment a talk we have, then:
- Still projectors
- Moving pictures
- Chalk talks
- Natural objects such as cones, leaves, etc.
- Experiments such as deposition of carbonate (applicable to small group)
- Microscopes and lenses.
Discussion
Following Mr. Yeager’s presentation of his paper on the use of visual materials, the following points were brought out in discussion:
Visual material used should be of the highest possible type; inferior material or illustrations greatly detract from the lecture and are worth less than nothing. Occasionally it may be necessary to use a lantern slide which has no great artistic merit but is important for a certain definite scientific purpose. There is never an excuse for using an inferior slide when an effort is being made to present an inspirational subject; and in this case, it is better to use no slide at all.
There are certain places where lantern slides might introduce an undesired formality into the program; in a natural setting an illustrated talk may be out of place. This, however, is a matter in which the judgment of the individual park naturalist must be exercised.
