About the Author and Acknowledgments

About the Author

Roberto Cardil Ricol is a Secondary School teacher of Mathematics in Spain. He studied as a teacher (Huesca University, Spain), and earned Bachelor of History (Barcelona University, Spain) and Bachelor of Mathematics (Zaragoza University, Spain) degrees. He has taught Mathematics to students from 6 years old to the University level. He maintains the site www.matematicasvisuales.com and enjoys the beauty of Mathematics.

Acknowledgments

I would like to thank Janet Beery, Convergence editor, for her support and encouragement. Without her help this article would not have been published.

I thank the anonymous referees for suggestions that improved the article.

I am grateful to the Carnegie Mellon University Libraries for granting permission to use images from their copy of Kepler's Nova stereometria doliorum vinariorum, held in the Posner Memorial Collection, in this article.

Miguel Cardil helped me in the artistic design of the page and also designed all graphic elements in the mathlets.

Finally, I would like to thank Kathleen Killorin for her help with the English translation.