How does an abacus work?
The Abacus was an instrument useful for various mathematical computations. This learning leaflet provides step-by-step instructions for the basic operations of the abacus
How does the Sextant symbolize the person who worked on the famed Hevelius star catalog and star atlas throughout its production, from observation to publication?
Elisabeth Hevelius, wife of Johann Hevelius, was an astronomer in her own right. They worked together in the observatory of their Gdansk home to measure angular widths and distances with a great sextant, which required two observers at a time. The Sextant was among the new constellations they proposed in Uranographia (1690), the most detailed and influential celestial atlas of the 17th century. The Uranographia contains 54 beautiful double page engraved plates of 73 constellations, and 2 oversized folding plates of planispheres.
Why were experimental variables (like tilt) so important?
Galileo described his experiment with an inclined plane in Two New Sciences. In this work, Galileo furthered a research tradition in physics known as "impetus." This tradition, begun in the 6th century CE with John Philoponos, sought to explain motion. A body falling straight down accelerates too fast to be measured, so Galileo constructed his inclined plane in order to study it in slow motion. Galileo's inclined plane provided experimental confirmation of the law of free fall.