He joined the Barnabites at the age of sixteen, and during his theological course at Rome studied at the same time meteorology and astronomy under Angelo Secchi.

From 1856 until 1890 he was attached to the Barnabite college at Moncalieri where he became widely known for his work in meteorology, a science which he advanced not merely by his personal observations and studies but also by the interest which he roused in it throughout Italy.

The success which attended his efforts gave him a national reputation, and in 1866 Senator Matteucci and Signor Berti, minister of public instruction, urged him to take charge of the department of meteorology at Florence.

Denza did not accept the post, but in the following year, at Berti's invitation, he read a paper on meteors at the "Instituto Superiore" in Florence.

He likewise represented the pope at the Paris astronomical congress of 1887, when the plan was formulated of making a photographic map of all the stars in the heavens down to the fourteenth magnitude; through his influence the Vatican Observatory was one of the eighteen chosen to carry out this important project.