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DIY tutorial glowing pendulum in the dark

Learn how to make a simple DIY pendulum using a ping pong ball and basic household materials. This step-by-step guide shows ...
Nature

Pendulum Observations in the Northern and Southern Hemispheres

THE figure of the earth has been determined by three independent methods of investigation, (1) By abstract mathematical calculation of the form which such a body as the earth, rotating as it does, ...