What do you call a balloon meant to carry passengers? The reflexive response seems to be “hot air balloon” (Vintage Views, Monitor, 3/19). Except at the birth of ballooning and the past fifty years, the most appropriate description would be “hydrogen balloon.” It’s true the first balloons launched in Paris in 1783 by the Montgolfier brothers were hot air balloons made of paper and linen and filled with heat from a fire below the launch platform. But these craft had a very limited flight range, ending when the hot air cooled. Almost immediately, other experimenters had a better idea: generate hydrogen by adding sulfuric acid to iron filings, pipe it into a cloth bag held within a net, and suspend a wicker basket for passengers. This kind of balloon crossed the English Channel in 1785, and first ascended in Portsmouth in 1796.
The balloon that rose from Concord’s State House lawn in 1838 and landed in Northfield was a hydrogen balloon, not a hot air balloon. Only with the development of liquid propane fuel and synthetic fabrics was it possible to return to hot air ballooning as a practical thing, generating the heat by a burner beneath the fabric envelope. This is new technology. As recently as the 1970s, a book on ballooning contrasted the deafening roar of the burner with the perfect silence of the hydrogen balloon, predicting that “the existence of these modern Montgolfier balloons will be of short duration, for the advantages of the gas balloon are overwhelming.”
James Garvin
Pembroke