pplied, and once in each
revolution each port in the case registered with the port in the
hollow shaft. The mixture which then entered the charging cylinder was
transferred to the corresponding working cylinder when the piston of
that cylinder had reached the end of its power stroke, and immediately
before this the exhaust ports diametrically opposite the inlet ports
were uncovered; scavenging was thus assisted in the usual way. The very
desirable feature of being entirely valveless was accomplished with this
engine, which is also noteworthy for exceedingly compact design.

The Lamplough six-cylinder two-stroke cycle rotary, shown at the Aero
Exhibition at Olympia in 1911, had several innovations, including a
charging pump of rotary blower type. With the six cylinders, six power
impulses at regular intervals were given on each rotation; otherwise,
the cycle of operations was carried out much as in other two-stroke
cycle engines. The pump supplied the mixture under slight pressure to
an inlet port in each cylinder, which was opened at the same time as the
exhaust port, the period of opening being controlled by the piston. The
rotary blower sucked the mixture from the carburettor and delivered it
to a passage communicating with the inlet ports in the cylinder walls.
A mechanically-operated exhaust valve was placed in the centre of each
cylinder head, and towards the end of the working stroke this valve
opened, allowing part of the burnt gases to escape to the atmosphere;
the remainder was pushed out by the fresh mixture going in through the
ports at the bottom end of the cylinder. In practice, one or other of
the cylinders was always taking fresh mixture while working, therefore
the delivery from the pump was continuous and the mixture had not to be
stored under pressure.

The piston of this engine was long enough to keep the ports covered
when it was at the top of the stroke, and a bottom ring was provided
to prevent the mixture from entering the crank case. In addition to
preventing leakage, this ring no doubt prevented an excess of oil
working up the piston into the cylinder. As the cylinder fired with
every revolution, the valve gear was of the simplest construction, a
fixed cam lifting each valve as the cylinder came into position. The
spring of the exhaust valve was not placed round the stem in the usual
way, but at the end of a short lever, away from the heat of the exhaust
gases. The cylinders were of cast steel,