This book is a classic treatise on plane and spherical trigonometry, with a focus on practical applications in surveying, navigation, and astronomy. It includes detailed explanations of the key concepts and definitions in trigonometry, as well as a range of exercises and problems to help readers develop their skills. With its comprehensive coverage and clear, accessible style, this book has remained a valuable resource for students and professionals alike. 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.