FLYING MACHINES TO-DAY. By WILLIAM D. ENNIS, M. E., Professor of Mechanical Engineering, Polytechnic Institute, Brooklyn. 12mo., cloth, 218 pp., 123 illustrations $1.50 net
CONTENTS: The Delights and Dangers of Flying--Dangers of Aviation--What it is Like to Fly. Soaring Flight by Man--What Holds it Up. Lifting Power. Why so Many Sails. Steering. Turning Corners--What Happens When Making a Turn. Lateral Stability. Wing Warping. Automatic Control. The Gyroscope. Wind Gusts. Air and the Wind--Sailing Balloons. Field and Speed. Gas and Ballast--Buoyancy in Air. Ascending and Descending. The Ballonet. The Equilibrator. Dirigible Balloons and Other Kinds--Shapes. Dimensions. Fabrics. Framing. Keeping the Keel Horizontal. Stability. Rudders and Planes. Arrangement and Accessories. Amateur Dirigibles. Fort Omaha Plant. Balloon Progress. Question of Power--Resistance of Aeroplanes. Resistance of Dirigibles. Independent Speed and Timetable. Cost of Speed. Propeller. Getting Up and Down; Models and Gliders; Aeroplane Details--Launching. Descending. Gliders. Models. Balancing. Weights. Miscellaneous. Things to Look After. Some Aeroplanes--Some Accomplishments. The Possibilities in Aviation--Case of the Dirigible. The Orthopter. The Helicopter. Composite Types. What is Promised. Aerial Warfare.

AERIAL FLIGHT. Vol. 1. Aerodynamics. By F. W. LANCHESTER. 8vo., cloth, 438 pp., 162 illustrations $6.00 net
CONTENTS: Fluid Resistance and Its Associated Phenomena. Viscosity and Skin Friction. The Hydrodynamics of Analytical Theory. Wing Form and Motion in the Periphery. The Aeroplane. The Normal Plane. The Inclined Aeroplane. The Economics of Flight. The Aerofoil. On Propulsion, the Screw Propeller, and the Power Expended in Flight. Experimental Aerodynamics. Glossary. Appendices.

Vol. II. Aerodonetics. By F. W. LANCHESTER. 8vo., cloth, 433 pp., 208 illustrations $6.00 net
CONTENTS: Free Flight. General Principles and Phenomena. The Phugoid Theory--The Equations of the Flight Path. The Phugoid 1852-1872. Dirigible Balloons from 1883-1897; 1898-1906. Flying Machine Theory--The Flight Path Plotted. Elementary Deductions from the Phugoid Theory. Stability of the Flight Path as Affected by Resistance and Moment of Inertia. Experimental Evidence and Verification of the Phugoid Theory. Lateral and Directional Stability. Review of Chapters I to VII and General Conclusions. Soaring. Experimental. Aerodonetics.

AERIAL NAVIGATION. A practical handbook on the construction of dirigible balloons, aerostats, aeroplanes and aeromotors, by FREDERICK WALKER. 12mo., cloth, 151 pp., 100 illustrations $3.00 net.
CONTENTS: Laws of Flight. Aerostatics. Aerostats. Aerodynamics. Screw Propulsion. Paddles and Aeroplanes. Motive Power. Structure of Airships and Materials. Airships. Appendix.

AEROPLANE PATENTS. By ROBERT M. NEILSON. 8vo., cloth, 101 pp., 77 illustrations $2.00 net
CONTENTS: Advice to Inventors. Review of British Patents. British Patents and Applications for Patents from 1860 to 1910, arranged in Order of Application. British Patentees, arranged alphabetically. United States Patents from 1896 to 1909, arranged in order of issue. United States Patentees, arranged alphabetically.