Clearly a man of considerable ingenuity. My guess is they are all his own design, although the three cylinder 'radial' steam engine (4th down) bears a resemblance to Edgar T Westbury's Cygnet.
I have no idea what 1 is.
2 appears to be a weir feed pump (one end is a steam power cylinder, the other pumps water)
3 is a spark ignition 2 stroke, possibly m eant for a boat (or just display) as it has a flywheel.
4 is the radial steam engine which should have an interesting valve arrangement behind that large cover at the back.
5 is an unusual stationary engine.
6 is a duplex feed pump.
7 is a very compact reversible engine, perhaps meant for a steam crane or similar.
Aside from the 2-stroke which may have suffered internal corrosion from the fuel, I would expect most of them to be restorable, with patience and care. Steam engines are tolerant of wear and minor leaks if you just want them to 'go' on low pressure steam or compressed air, rather than work hard. The presence of lubricators on several engines suggests your great-grandfather meant these engines to be run on steam, not just display models.
If the brass has not deteriorated and become brittle or corroded, then 'restoration' could mainly be a careful strip down, cleaning and relubricating. Gaskets will probably need replacing with new ones, and glands will need repacking. Be thankful that he hardly used steel components, if at all.
A great find, and a nice heirloom for anyone with an interest in things mechanical.
Neil
Edited By Stub Mandrel on 26/10/2013 20:26:12