Report of the J adges on the 
This engine difl'crs from the ordinary locomotive tyi^e, and it does so in this 
particular, that although the boiler is, as a whole, of the locomotive form, it 
has added to it in the tire-box, 10-25-iiich diameter wrought-iron bent water- 
tubes, of the Davey-Paxman character, such as were introduced by this firm at 
Oxford (1870) in their 4-horse semi-portable. The upper ends of these tubes 
arc provided with deflectors, to cause the current, as it rises through them, to 
be dispersed horizontally. 
The cylinder is bolted on to the fire-box and is steam-jacketed, as also are 
the covers. 
The crank-shaft, which is near the smoke-box, is supported in brasses, one 
pair of which are adjusted sideways, and the other pair, near the fly-wheel, are 
adjusted vertically. The brasses are supported in cast brackets bolted to the 
rig. 3. — Indicator-diagram of Messrs. Davey, Paxman, and Davey's 
Portable Steam Engine, No, 4959 (No. ^ diagram, 32 lbs. spring.) 
boiler. The crank is a " bent " crauk, and is made of steel. The engine is 
balanced at the fly-wheel. 
The four guide-bars are cast iron. 
The guide-blocks are also cast iron, and the adjustment for wear is made by 
letting the bars together. 
The steam is admitted to the cylinder through a regulator, and then passes 
an expansion-valve into the slide-jacket. 
The main slide is an ordinary short D slide. The expansion slide is a small 
gridiron valve, taking steam in over the end and through four openings. Q"he 
travel of this slide is y^ths. It is driven by the oscillating movement of a spindle, 
carrying a lever situated in the expansion slide-box, and having a gun-metal 
block on its end, which gives motion to the slide. The spindle does not imss 
