60 
Report of the Judges on the 
them, passap;cs to admit the steam from expansion-valves, woi'ldng on tlic 
baclc of the ]irincipal slides ; these passa'j;es are vertical in the working face of 
the main slides, but are at an angle of 52° to the horizontal in the back faces 
of those slides, the passages being twisted in tlicir progress through the body 
of the slide. The pair of expansion slides are of gun-nietal, and have bevelled 
ends, at the same angle (52°) as the openings in the main slides. The expansion- 
slides are driven by a slide-stalk, 
having on it a pair of eccentrics, 
working in blocks carried in brackets 
attached to the liacks of tlie expan- 
sion-slides, in which brackets the 
blocks are free to slide. The slides 
are driven by the sides of the eccentrics ; 
and hy their circumference, on the 
]>artial revolution of the slide-stalk, 
the expansion-slides can be rai.sed 
or lowered. As the ends of these 
slides are bevelled, the raising oi" 
lowering has the effect of lengthening 
or shortening the expansion-slide in 
relation to the angled passage in the 
main-slide, and thus of varying the 
expansion. The expansion-slides have 
bridges over their backs, and are 
adjusted to fit these'bridges in order 
to remove a portion of the pressure 
of the steam. The bridges are sepa- 
rate from the slide-jacket, and are 
fitted against stops, np to which they 
are pressed by springs at their backs, 
so that in the event of there being 
any water in the cylinder, both slides 
and bridges yield, and allow of its- 
escape. 
There are two eccentrics, one for 
the principal slide, and one for the 
expansion-slide, in the nsual manner. 
That for the principal slide is driven 
by a jilate having two holes in it, the 
one for head, the other for stern gear. 
The expansion-slide is set midway, so 
as to suit either head or stern gear. 
Immediately beyond the guide in 
which the expansion slide-stalk works, 
there is a socket in which the stalk 
can turn, and on the slide-stalk there 
is an arm worked by the governor, so 
that as the governor rises or falls, 
it causes the expansion slide-stalk to 
make a portion of a revolution, and 
thus to raise or lower the back slides, 
to vary the amount of expansion, and to regulate the speed of the engine. 
There is no throttle-valve, nor any apparatus whatever, other than these 
slides, for the purpose of regulation. 
The centre line of the engine is not parallel with that of the boiler, the crank 
shaft end being somewhat the higher. 
to 
'CD 
