Ok.
Starley decided on a 52” gear for two reasons.
1/ It represented the most popular size Penny Farthing, and
2/ The fully clothed, untrained, raw beginner could keep 12.5 mph, at 100 Watts output at 80 cadence for an enjoyable afternoon bicycle ride.
Nowadays, we buy lighter bikes with higher gears than 52”, and wear cycling specific clothes that are much lighter than a tweed suit.
The early responses to the OP’s question were 28 and 36 minutes for ten miles. Tell me how this helps the OP?
I said, “40 minutes will be your initial target.”
I am presuming the OP will be riding a circular route, in which case, wind speed and hills won’t make much difference to riding a flat road in the calm.
The OP asked for our estimations of an ‘average’ time, so I can only presume the OP regards themself of ‘average’ fitness. ????