I placed this picture of a Rosebery Pumper on one of my pictures pages (Science Works Power of the Past Exhibition) and a gentleman by the name of Mr Ted Lee e-mailed me and related this wonderful story from his personal experience with just such a beast. Ted is not the owner of the engine in this photo. Please enjoy the story below, Ted has quite the way with words and I've asked him if he would not mind contributing more in the future.
The following message is by Mr Ted Lee and is © Copyright 1998 Ted Lee used with his permission with my thanks.
In my younger days sixties & early seventies around Emerald on QLD's Central Highlands I worked on many and varied old engines (I didn't think of them as OLD just well used).
I haven't got information particularly on the Rosebery Pumper, but what I have may be helpful. Buzzacott, Ronaldson Tippet & the Toowoomba foundry (Southern Cross QLD) made Pumpers under license to someone, and I wouldn't be surprised if there were a few more manufacturers out there.
These engines were notoriously unreliable (because of the crude carby setup the fuel mixture needed to be readjusted as the fuel level dropped, bit of a pain when the bore was down the back of the 6 mile paddock.) They ran beautifully while you stood there watching them, but as soon as you turned your back they would stop. As you rode away on your horse you would keep turning in the saddle trying to hear if it was still going. My cousin said "You have to drop your hat beside it then sneak away through the spear grass so that it doesn't see you leave."
One real serious problem these engines had was wear in the cam shaft which, after a lot of work, failed to lift the exhaust valve high enough for the governor arm to catch then they would simply keep on revving until the poorly balanced fly-wheel tore the thing apart. A property owner I knew went to start his Pumper up one day and found that "There was no engine to start" he found the fly-wheel nearly 400 meters away. My Uncle gave me one that had over-revved and broken the magneto cog which saved it from total destruction, I resurrected it and gave it to a friend at Longreach, his children took it to High School because you could see all the moving parts, it would literally run on an oily rag (soaked in petrol).
These engines were made a long time before the 1940s and were still being made possibly into the fifties. Southern Cross in the sixties replaced the engine part of the setup with a Villiers 2 or 4 HP motor, retaining the crown-wheel and pinion, mountings & legs of the original.