Tuesday, December 16, 2008

Adventkalender, 16. Dezember

US-Patent 4796017: "Low water level alarm for Christmas tree stand" von Joseph T. Merenda, eingereicht am 20. Jänner 1987 ("A resistive water probe is used in combination with a Christmas tree stand to detect a low water level. A low water situation activates lights in a Christmas tree ornament").

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