The English equivalent of “On voyait s’élever” could be “one could see rising…”. “On leur répondait” is simply “We would tell them that…” or “We would respond with…”.

As for “c’était le « pigeon » de M. Ader”, as far as I know, Clément Ader was said to be fascinated by birds [<< Le vol des oiseaux et des insectes m’a toujours préoccupé >> – Clément Ader. ] This could thus be a reference to that – Ader built his flying machines based on research on the flight of birds (often “bat-like”, as the passage states).

Hope this helps.

You get the point quite well, I may rephrase your translation to make it a bit more accurate : “On voyait s’élever” stands for “It was seen rising sometimes during the few past years (mentioned at the start of the text)” .

As for “c’était le « pigeon » de M. Ader et rien de plus” , the direct hidden meaning is that people there didn’t care about what it was and didn’t want to further investigate. Of course, the object was not a pigeon, that’s for the guillemets.

Sometimes in English, one shifts to another tense for descriptions of ongoing things where imperfect is used in French. Imperfect can be rendered in a number of ways. The idea is to get the overall description of actions in terms of tenses to make sense in English. Also, the word ENSUITE, sounds like they looked for info after it had flown by….that placement of ensuite is the reason for my moving the idea of peculiar sight (phénomène) to the beginning of the sentence.

Passive and imperfect in French:

In the Haute Garonne, in chateau gardens on the outskirts of Paris, a gigantic bird, a sort of bluish bat gliding some fifteen meters above the ground, had been seen rising into the sky. After seeing this peculiar sight, the lucky onlookers then tried to get information on the singular machine. They were told that it was nothing more than Monsieur Ader’s “pidgin” flying around.