708 
The Trials of Oil Engines at Cambridge. 
7 brake liorse-power, and costs 120 1. It embodies an application 
of Root’s patent oil feed. A section of this is shown in fig. 7. 
A grooved spindle reciprocates in and out of an oil bath, past a 
port in the main air passage. The air, entering through a spiral 
heater, sucks the oil off the exposed grooves, and passing down 
through a prolongation of this heater, which forms the vaporiser, 
is admitted by the main air valve into the ignition passage. 
The governor, of the ordinary ball type, raises or lowers the end 
of a connecting-link, which drives the spindle upon a stepped 
distance piece, and so lengthens or shortens its stroke. This is 
shown in fig. 8. In this way the number of grooves which 
enter the oil bath and are filled is varied, and the richness of the 
vapour charge correspondingly modified. The vaporiser is heated 
by a central lamp, which also heats the ignition tube, and the 
lamp blast is supplied by a pump driven by the lay shaft. An 
oil-pump is also worked in the same manner for filling the oil 
bath from the main tank in the engine bed. 
Three cams on the lay shaft Are] arranged to give no com- 
pression, half compression, and full compression, and a pin fitting 
