Charles Green balloon pioneer

[MartinR]

Coal gas is roughly equal volumes of carbon monoxide and hydrogen.  CO has no lifting properties, it is nearly as dense as air (mw of CO is 28, air is usually taken as 29).  The lift only comes from the hydrogen and therefore a coal gas balloon will have approximately half the lifting power of a hydrogen balloon.  Of course doubling the size of the balloon will restore the lift.

[Smiffy]

Just a small correction - apparently Green used coal gas to lift his balloons, which at the time was cheaper and easier to produce than hydrogen.

[Jackie Paper]

Here's an interesting image of Charles Green's hot air balloon, the Nassau, over the Medway at Chatham in 1836.
A Londoner, he took off from Vauxhall Gardens and came down at Cliffe an hour and a half later.
I imagine the riverscape was added as a background by studying a map, but the effect of height is quite realistic.

Later that year he flew across the channel from Vauxhall to Germany, 500 miles in 18 hours. A long distance record at the time, although the Channel was first crossed by air long before, in 1785, by a Frenchman and a newly-minted American.