and had the lowest weight
per horse-power of any.

The Anzani radial was considerably developed special attention being
paid to this type by its makers and by 1914 the Anzani list comprised
seven different sizes of air-cooled radials. Of these the largest had
twenty cylinders, developing 200 brake horse-power--it was virtually
a double radial--and the smallest was the original 30 horse-power
three-cylinder design. A six-cylinder model was formed by a combination
of two groups of three cylinders each, acting upon a double-throw
crankshaft; the two crank pins were set at 180 degrees to each other,
and the cylinder groups were staggered by an amount equal to the
distance between the centres of the crank pins. Ten-cylinder radial
engines are made with two groups of five cylinders acting upon two
crank pins set at 180 degrees to each other, the largest Anzani 'ten'
developed 125 horsepower at 1,200 revolutions per minute, the ten
cylinders being each 4.5 inches in bore with stroke of 5.9 inches, and
the weight of the engine being 3.7 lbs. per horse-power. In the 200
horse-power Anzani radial the cylinders are arranged in four groups of
five each, acting on two crank pins. The bore of the cylinders in this
engine is the same as in the three-cylinder, but the stroke is increased
to 5.5 inches. The rated power is developed at 1,300 revolutions per
minute, and the engine complete weighs 3.4 lbs. per horse-power.

With this 200 horse-power Anzani, a petrol consumption of as low as 0.49
lbs. of fuel per brake horse-power per hour has been obtained, but
the consumption of lubricating oil is compensatingly high, being up to
one-fifth of the fuel used. The cylinders are set desaxe with the
crank shaft, and are of cast-iron, provided with radiating ribs for
air-cooling; they are attached to the crank case by long bolts passing
through bosses at the top of the cylinders, and connected to other bolts
at right angles through the crank case. The tops of the cylinders are
formed flat, and seats for the inlet and exhaust valves are formed on
them. The pistons are cast-iron, fitted with ordinary cast-iron spring
rings. An aluminium crank case is used, being made in two halves
connected together by bolts, which latter also attach the engine to the
frame of the machine. The crankshaft is of nickel steel, made hollow,
and mounted on ball-bearings in such a manner that practically a
combination of ball and plain bearings is obtained; the centra