fore the days of the
high-tension magneto and the almost perfect ignition systems that makers
now employ. The scheme of ignition for this engine was originated by
Manly himself, and he also designed the sparking plugs fitted in the
tops of the cylinders. Through fear of trouble resulting if the steel
pistons worked on the steel cylinders, cast iron liners were introduced
in the latter, 1/16 of an inch thick.

The connecting rods of this engine were of virtually the same type as is
employed on nearly all modern radial engines. The rod for one cylinder
had a bearing along the whole of the crank pin, and its end enclosed the
pin; the other four rods had bearings upon the end of the first rod,
and did not touch the crank pin. The accompanying diagram shows this
construction, together with the means employed for securing the ends of
the four rods--the collars were placed in position after the rods had
been put on. The bearings of these rods did not receive any of the
rubbing effect due to the rotation of the crank pin, the rubbing on them
being only that of the small angular displacement of the rods during
each revolution; thus there was no difficulty experienced with the
lubrication.

Another early example of the radial type of engine was the French
Anzani, of which type one was fitted to the machine with which Bleriot
first crossed the English Channel--this was of 25 horse-power. The
earliest Anzani engines were of the three-cylinder fan type, one
cylinder being vertical, and the other two placed at an angle of 72
degrees on each side, as the possibility of over-lubrication of the
bottom cylinders was feared if a regular radial construction were
adopted. In order to overcome the unequal balance of this type, balance
weights were fitted inside the crank case.

The final development of this three-cylinder radial was the 'Y' type of
engine, in which the cylinders were regularly disposed at 120 degrees
apart, the bore was 4.1, stroke 4.7 inches, and the power developed was
30 brake horse-power at 1,300 revolutions per minute.

Critchley's list of aero engines being constructed in 1910 shows twelve
of the radial type, with powers of between 14 and 100 horse-power, and
with from three to ten cylinder--this last is probably the greatest
number of cylinders that can be successfully arranged in circular form.
Of the twelve types of 1910, only two were water-cooled, and it is to be
noted that these two ran at the slowest speeds