I. GEOMETRICAL AND GRAPHICAL ESSAYS. This Work contains, 1. A select Set of Geometrical Problems, many of which are new, and not contained in any other Work. 2. The Description and Use of those Mathematical Instruments that are usually put into a Case of Drawing Instruments. Besides these, there are also described several New and Useful Instruments for Geometrical Purposes. 3. A complete and concise System of SURVEYING, with an Account of some very essential Improvements in that useful Art. To which is added, a Description of the most improved THEODOLITES, PLANE TABLES, and other Instruments used in Surveying; and most accurate Methods of adjusting them. 4. The Methods of LEVELLING, for the Purpose of conveying Water from one Place to another; with a Description of the most improved Spirit Level. 5. A Course of PRACTICAL MILITARY GEOMETRY, as taught at Woolwich. 6. A short Essay on Perspective. The Second Edition, corrected, and enlarged with the Descriptions of several Instruments unnoticed in the former Edition, by W. JONES, Math. Inst. Maker; illustrated by 35 Copper-plates, in 2 vols. 8vo. Price 14s. in Boards. II. AN ESSAY ON ELECTRICITY, explaining clearly and fully the Principles of that useful Science, describing the various Instruments that have been contrived, either to illustrate the Theory, or render the Practice of it entertaining. To which is added, A LETTER to the AUTHOR, from Mr. JOHN BIRCH, Surgeon, on MEDICAL ELECTRICITY. Fourth Edition, 8vo. Price 6s. illustrated with six Plates. III. AN ESSAY ON VISION, briefly explaining the Fabric of the Eye, and the Nature of Vision; intended for the Service of those whose Eyes are weak and impaired, enabling them to form an accurate Idea of the State of their Sight, the Means of preserving it, together with proper Rules for ascertaining when Spectacles are necessary, and how to choose them without injuring the Sight. 8vo. Second Edition. Illustrated with Figures. Price 3s. in Boards. IV. ASTRONOMICAL AND GEOGRAPHICAL ESSAYS, containing, 1. A full and comprehensive View of the general Principles of Astronomy, with a large Account of the Discoveries of Dr. Herschel, &c. 2. The Use of the Globes, exemplified in a greater Variety of Problems than are to be found in any other Work; arranged under distinct Heads, and interspersed with much curious but relative Information. 3. The Description and Use of Orreries and Planetaria, &c. 4. An Introduction to Practical Astronomy, by a Set of easy and entertaining Problems. Third Edition, 8vo. Price 10s. 6d. in Boards, illustrated with sixteen Plates. V. AN INTRODUCTION TO PRACTICAL ASTRONOMY, or the Use of the Quadrant and Equatorial, being extracted from the preceding Work. Sewed, with two Plates, 2s. 6d.