Proceedings of the First Park Naturalists’ Training Conference, November 1 to 30, 1929



By Dorr G. Yeager

I believe it is generally agreed that a more effective lecture can be given with slides and other illustrative material than when the lecturer depends wholly upon his personality to put it across. The trend is more and more toward the illustrated type in our National Parks. Last year we established two in Yellowstone and next year we hope to add three more.

The advantages of an illustrated lecture are many fold. It enables the lecturer to better illustrate his point. A picture on the screen is remembered much longer by the audience than a word picture. By means of slides, a man can give a comprehensive bird lecture where a mere description of the different birds would fail utterly.

n placing illustrated lectures in a national park several things should be considered. The ideal situation is, of course, to place the lecture in a special room for the purpose. We are encountering difficulty in Yellowstone in finding a suitable place at several lodges to give these lectures. The lights must be turned out and in the lobby many tourists, not interested in the lecture, complain at being forced to sit in the dark throughout the talk. If size permits, the lights may be turned off in one section of the lobby and burned in the other section. We have had great success in holding the lectures in the recreation room of the lodge before the evening program. This enables those who do not wish to attend the talk to remain in the main lobby until after it is over.

The subject matter in one of these talks is vitally important and the treatment will vary with the different parks. In Yosemite it is possible to give different lectures each evening. In Yellowstone, however, care must be exercised that the lectures do not overlap or repeat in order that the visitor may get fresh material each evening. As a rule, about 20 slides are necessary for a talk of 30 minutes. Slides should be available on all subjects relating to the park. These slides should eventually be stored in Moler cabinets similar to the one in Mr. Hall’s office. The type of machine is not so important, although several features should be insisted upon. A double dissolving effect is desired. This may be obtained by purchasing two machines and hooking them up in series.* This not only gives the double dissolving effect, but it also makes two machines immediately available in case of emergency. A water cell should be in the equipment.**

* Bausch and Lomb Optical Co. makes a fine portable double dissolving lantern which is more convenient end lower in price than two machines. It is the Ballopticon Model BB.


** Not necessary for double dissolving lanterns.


It is also necessary to study the conditions before deciding on the type to purchase. If the lecture is to be given out of doors with semi-light conditions, especially if there is a long throw, an arc machine should be obtained. If, on the other hand, it is to be given in a hall where darkness is available, a bulb machine is best suited. An arc throws the stronger light but it is not always necessary to have such strength. It is advisable also to have in the equipment a small portable projector ready for instant use. Many of these are on the market at present.