There has been an obvious need in the Geological Survey o£ a paper devoted wholly to illustrations. No complete paper on the character, use, and mode of preparation of illustration has been published by the Survey, though brief suggestions concerning certain features of their use have been printed in connection wit other suggestions pertaining to publications. The present paper includes matter which it is hoped will be of service to authors in their work of making up original drafts of illustrations and to drafsmen who are using these originals in preparing more finished drawing but it is not a technical treatise on drafting.