Michel Chasles presents two groundbreaking geometrical memoirs in this seminal work on cones. With clear and concise descriptions, Chasles lays out his discoveries on the general properties of cones of the second degree and the spherical conics. Complete with detailed notes and additions by C. Graves, this book is essential reading for anyone interested in the history of geometry. This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work is in the "public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.