Geometrical Propositions Demonstrated Or A Supplement To Euclid: Being A Key To The Exercises Appended To Euclid�������s Elements (1840) is a book written by William Desborough Cooley. The book serves as a supplement to Euclid�������s Elements and provides a key to the exercises found in the original text. It contains a collection of geometrical propositions that are demonstrated through diagrams and mathematical proofs. The book is intended for students of geometry and mathematics who are studying Euclid�������s Elements and need additional guidance and explanation of the concepts presented in the text. The author, Cooley, was a British mathematician and engineer who was known for his work in the field of railway engineering. He was also a Fellow of the Royal Society and a member of the Institution of Civil Engineers. This book is a valuable resource for anyone studying geometry and mathematics and provides a comprehensive guide to understanding the concepts presented in Euclid�������s Elements.This scarce antiquarian book is a facsimile reprint of the old original and may contain some imperfections such as library marks and notations. Because we believe this work is culturally important, we have made it available as part of our commitment for protecting, preserving, and promoting the world's literature in affordable, high quality, modern editions, that are true to their original work.