room with a large picture window
scotch tape (™ 3M Corp)
overhead projector bulb
overhead projector stand
silicone aquarium sealant (one tube should be sufficient)
butcher paper sufficient to cover picture window
multiple siphons long enough to reach a bathtub or sink from your designated window (these may be shared among members of the class; sign up for a time to use them if you do not have your own, or are unable to purchase your own, or else substitute a pitcher)
aquarium (approximate dimensions: 6" H x 40"L x 16" W; consult me if you are unsure whether your pre-made aquarium may be used)
approximately 15-16 gallons of water (amount will vary according to aquarium dimensions)
30-35 small goldfish or 5-10 large koi
two wood or metal stands (to be custom-built)
aquarium thermometer (inside-mounted preferable)
Ms. Guilford wishes to publicly acknowledge the assistance of Mr. Schaffer and his fifth period Industrial Arts class for their offer of expert help in constructing custom aquariums and support stands. This project counts for course credit in Industrial Arts; interested students should contact Mr. Schaffer, room 15, for details.
1. Tape a single sheet of butcher paper over the picture window.
2. Place the overhead projector, on its stand, in front of the window. Turn it on (make sure the bulb is installed and functioning).
3. Adjust the distance of the projector from the window until the image fits precisely in the window.
4. Adjust the focus of the projector so that the image projected on the window is as sharp as possible, then turn off the projector.
NOTE: you may require some assistance for steps 5-8.
5. Place the stands on either side of the projector. They should be sturdy enough to support about 60 pounds of weight. The tops of the stands should be slightly taller than the top of the overhead projector (one inch or less if on carpet, less than a quarter-inch if on wood, stone, tile, or concrete floor).
6. Carefully place the aquarium across the tops of the stands and the projector. For best results, the bottom of the aquarium should be resting just above, or else flush with, the top of the projector.
7. Unplug the projector.
8. Slowly fill the aquarium with water. Be alert for any leakage (especially from corners).
ATTENTION: If any leakage is detected, stop filling the aquarium immediately and empty it with a siphon, pitcher, etc. until it can be moved to a different location and dumped out. You must then allow the aquarium to dry before resealing the edges and corners according to the silicone manufacturer's instructions. Also take care to dry the projector, stands, etc. thoroughly before proceeding.
9. When the aquarium is full, clean up any water spills and then plug in the projector and turn it on.
10. Recheck the focus of the image produced on the butcher paper and adjust as needed. (You should not need to make a large adjustment.)
11. Add the goldfish to the aquarium.
12. Your butcher paper should now be the screen on which a projection of the goldfish (viewed from top down) is being shown. You may decrease the water depth for slightly sharper shadows, though this will increase ripple visibility from the goldfish, and may also make the glass more prone to breakage, due to temperature differences. For the first few hours of operation, monitor the water temperature; goldfish and koi are relatively hardy over a range of water temperatures but the heat output of the projector may vary according to make and model; if water temperature goes above 80ºF (27ºC), add more water (if possible), cool the room, or shut down the projector for 18-24 hours. You should also go outside and view your projection.
WARNINGS AND ADMONISHMENTS:
Under NO circumstances should you leave the projector in continuous operation for more than two hours; though the water should serve to buffer extreme temperature changes in the glass, it is still only glass, and will break if overheated. You may connect the projector's electrical plug to an outlet via a 24-hour timer (available at most department stores): I would recommend setting the timer to run the projector from 9 to 11 PM and 1-3 AM (plus an optional 5-7 PM run during the winter, when the nights are longer.).
Do not leave the projector unattended while in operation.
Overfilling the aquarium may increase mechanical strain and lead to breakage of the aquarium glass, the projector glass, or both.
Students concerned about animal cruelty may substitute other items for the goldfish, subject to my approval; some mechanism to provide continuous object motion must be included in the proposal or it will be rejected.
Goldfish will die if not fed regularly. Frequent cleaning (at least every three or four days) of the bottom of the tank will be necessary as well.
Water will evaporate from the tank over time and must be replaced with fresh dechlorinated water (at least every two weeks).
Algae will grow on the sides and bottom of the tank and should be regularly removed to maintain transparency of the projection.
The presence of water in this electrical installation greatly increases the risk of shock. Always disconnect the apparatus from the power supply when performing aquarium maintenance. Whenever possible, have a parent, guardian, or other student in the room when making adjustments to the projector, aquarium, stands, etc.
Extra Credit Opportunity: Students will be given extra credit for completing, prior to set-up of this project, an electrical safety program given by the local Red Cross chapter. Contact me no later than June 7 if you wish to sign up.