Seed germination temperatures you can get from a number of sources,
the old Thompson and Morgan seed germination guide is at
http://www.backyardgardener.com/tm.html

As for Cyclamen, http://www.cyclamen.com/ contains all the information
anybody needs to grow commercial F1 hybrid Florists' Cyclamen,
including a full commercial grower's manual if you register on the
site.

Again many thanks for your help Rod. Two very good sites and sound
information of your own. One final thought is that this started as I
measured a temperature gradient of 30F from the bottom of a plant pot to the
top (2.5 inches). And it this that raised the question of what temperature
and where do you measure it. I had never considered the point before having
not had a heated propagator, I had naively assumed there was a constant
temperature. But on reflection every propogator must exhibit this. 2
inches of sand or soil is a good insulator, and a feature of good insulators
is that they exhibit a steep temperature gradient across themselves - as in
double glazed windows, 70F one side and 32F a inch away on the other side.
The only way round this is to have the pots lifted off the bottom and so
suspended in warm air that circulates and consequently is all at the same
temperature. I shall have to experiment.

Cheers Peter