We know little about his life.
A friend of Mersenne and a correspondent of Gassendi, Le Tenneur lived
in Paris until around 1645, then moved to Clermont-Ferrand, where
he assumed the role of Counsellor in the local senate.
Le Tenneur is the author of one volume, the De motu naturaliter
accelerato, published in 1649, in which he enters the debate taking
place in France over the new dynamic theories announced by Galileo.
He opposed the judgements of the Jesuits Pierre Le Cazre and Honoré
Fabri, who discounted the validity of the galileian thesis by their
hypothesis that the increase of distance passed in equal times by
a falling body being equal to the progression of odd numbers. He defended
the Pisan scientist's conclusions, demonstrating, that, as Galileo
had claimed, the acceleration of a falling body is directly related
to time, not space.
In January, 1648, Mersenne wrote to Le Tenneur,
asking him to carry out an experiment aimed at measuring atmospheric
pressure. The idea was to carry a barometer to the summit of the Puy-de-Dôme,
and check to see if the mercury levels had changed during the ascent.
The experiment was not carried out (it would in fact be Perier who
performed it for Pascal, that same year). Le Tenneur expressed the
mistaken conviction that the liquid level in the barometric tube would
show, even at altitude, the same levels recorded at sea-level.