n 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:--

Division General Mensier, Chairman; Division General Delambre, Inspector
General of the Permanent Works of Coast Defence, Member of the Technical
Committee of the Engineering Corps; Colonel Laussedat, Director of the
Conservatoire des Arts et Metiers; Sar