Geodesy is the study of the shape and size of the Earth, and of variations in its gravitational field. The Earth was originally believed to be flat, but many clues, such as the manner in which ships appear and disappear at the horizon, and the changed perspective from an elevated vantage point, as well as astronomical phenomena, convinced savants of its spherical shape. In the third century BC, Eratosthenes accurately estimated the circumference of the Earth [TM137 or search for “thatsmaths” at irishtimes.com].

## Posts Tagged 'Pythagoras'

### The Tunnel of Eupalinos in Samos

Published September 1, 2016 Irish Times Leave a CommentTags: Geometry, Pythagoras

The tunnel of Eupalinos on the Greek island of Samos, over one kilometre in length, is one of the greatest engineering achievements of the ancient world [TM098, or search for “thatsmaths” at irishtimes.com].

Approximate course of the tunnel of Eupalinos in Samos.

### The Biggest Harp in Ireland

Published September 4, 2014 Irish Times Leave a CommentTags: Geometry, Pythagoras, Wave Motion

This week’s *That’s Maths* column in *The Irish Times* (TM052, or search for “thatsmaths” at irishtimes.com) is about “Samuel Beckett Playing Bridge in Dublin”.

Every pure musical tone has a frequency, the number of oscillations per second in the sound wave. Doubling the frequency corresponds to moving up one octave. A musical note consists of a base frequency or pitch, called the *fundamental* together with a series of *harmonics*, or oscillations whose frequencies are whole-number multiples of the fundamental frequency.

That’s Maths in the *Irish Times* this week ( TM024: search for “thatsmaths” ) deals with perspective in art and its mathematical expression as projective geometry.

### Pythagoras goes Global

Published April 11, 2013 Occasional Leave a CommentTags: Pythagoras, Spherical Trigonometry

Spherical trigonometry has all the qualities we expect of the best mathematics: it is beautiful, useful and fun. It played an enormously important role in science for thousands of years. It was crucial for astronomy, and essential for global navigation. Yet, it has fallen out of fashion, and is almost completely ignored in modern education.

Continue reading ‘Pythagoras goes Global’