The A.B.C. 'Wasp II,' made by Walton Motors, Limited, is a seven-cylinder radial, air-cooled engine, the cylinders having a bore of 4.75 inches and stroke 6.25 inches. The normal brake horse-power at 1,650 revolutions is 160, and the maximum 200 at a speed of 1,850 revolutions per minute. Lubrication is by means of two rotary pumps, one feeding through the hollow crankshaft to the crank pin, giving centrifugal feed to big end and thence splash oiling, and one feeding to the nose of the engine, dropping on to the cams and forming a permanent sump for the gears on the bottom of the engine nose. Two carburettors are fitted, and two two-spark magnetos, running at one and three-quarters engine speed. The total weight of this engine is 350 lbs., or 1.75 lbs. per horse-power. Oil consumption at 1,850 revolutions is.03 pints per horse-power per hour, and petrol consumption is.56 pints per horsepower per hour. The engine thus shows as very economical in consumption, as well as very light in weight. The A.B.C. 'Dragon Fly 1A 'is a nine-cylinder radial engine having one overhead inlet and two overhead exhaust valves per cylinder. The cylinder dimensions are 5.5 inches bore by 6.5 inches stroke, and the normal rate of speed, 1,650 revolutions per minute, gives 340 horse-power. The oiling is by means of two pumps, the system being practically identical with that of the 'Wasp II.' Oil consumption is.021 pints per brake horse-power per hour, and petrol consumption.56 pints--the same as that of the 'Wasp II.' The weight of the complete engine, including propeller boss, is 600 lbs., or 1,765 lbs. per horse-power. These A.B.C. radials have proved highly satisfactory on tests, and their extreme simplicity of design and reliability commend them as engineering products and at the same time demonstrate the value, for aero work, of the air-cooled radial design--when this latter is accompanied by sound workmanship. These and the Cosmos engines represent the minimum of weight per horse-power yet attained, together with a practicable degree of reliability, in radial and probably any aero engine design. APPENDIX A GENERAL MENSIER'S REPORT ON THE TRIALS OF CLEMENT ADER'S AVION. Paris, October 21, 1897. Report on the trials of M. Clement Ader's aviation apparatus. M. Ader having notified the Minister of War by letter, July 21, 1897, that the Apparatus of Aviation which he had agreed to build under the conditions set forth in the convention of July 24th, 1894, was ready, and therefore requesting that trials be undertaken before a Committee appointed for this purpose as per the decision of August 4th, the Committee was appointed as follows:--