The hologram is mounted at an angle and illuminated from above by a bright point source. It includes the configuration of the planets on April 26, 1832 and December 31, 1999. Why did they choose these dates?

Laplace, who invented the orrery, had an interesting exchange with Napolean when he presented one of his devices to the emporer. Napolean examined his orrery and stated, "How can this be! You made the system of the world, you explain the laws of all creation, but in all your book you speak not once of the existence of God!" Laplace responded, "[No, Sire,] I had no need of that hypothesis." See Wikiquote for further information and other translations.

The photographs above show the set of three white light holograms on a single stand with close-ups of the two scenes of the orrery hologram as described above.

The hologram is mounted at an angle and illuminated from above by a bright point source. It includes three successive views of a really ugly man turning into a really scary werewolf. Don't let your young children see this one.

The photographs above show the display setup with three white light holograms and close-ups of two scenes from the werewolf hologram.

Hand out small squares of black paper with pins to the class members to do this experiment.

Punch a pinhole in the paper and hold the paper about an inch from your eye (within the near point of the eye) while viewing a white surface through the pinhole. Raise the pinhead from below into the line of sight between the pinhole and your eye. Because the "image" is actually a shadow on the retina, it is not inverted by the eyelens, and appears to be coming from above.

In this experiment the arc lamp acts both as a source of ultraviolet radiation for discharging the zinc plate and as a bright light to shadow project the apparatus.

A zinc plate connected to an electroscope and charged positive will not discharge under the influence of ultraviolet radiation. When the plate is charged negative, however, light from the arc lamp, which contains much UV, will discharge the plate, as indicated by the electrometer. A 1/8" glass plate inserted into the light from the arc lamp prevents passage of UV and the discharge ceases. Removing the glass plate allows the discharge to continue.

A zinc plate connected to an electroscope and charged positive will not discharge under the influence of ultraviolet radiation from the black light. When the plate is charged negative, however, UV light will discharge the plate, as indicated by the electrometer. A 1/8" glass plate inserted into the light from the UV bulb prevents passage of UV and the discharge ceases. Removing the glass plate allows the discharge to continue.

This process is quite slow due to the low intensity light source; demonstration P2-02 is recommended over this one in most circumstances.

NOTE: This arrangement does not work to show that a positive zinc plate will NOT be discharged by the UV source. If you wish to show the effect with both positive and negative charge on the plate you must use the carbon arc lamp, Demonstration P2-02.