A Lofty Mountain, Putrefying Flesh, Styptic Water, and Germinating Seeds: Methodological Reflections on Experimental Procedures from Pascal and Perier to Redi and Beyond
Nico Bertoloni Meli

This paper examines the rise of the "parallel trial" as an
experimental procedure in the second half of the 17th century. By
"parallel trial" I mean the notion of performing two parallel
experimental trials with minimal variations in order to weed out those
events and phenomena naturally occurring in nature as opposed to those
generated by the experimental setup. Clearly the notion of "parallel
trial" is related to the modern notion of control experiment, but
whereas this notion has been codified in a standardized set of
procedures, the 17th-century practices I investigate were considerably
looser: for example, mathematical/statistical methods for handling the
results were lacking, the number of cases in the two parallel trials
was not the same, or the conditions in which the trials were carried
out were not spelt out. Therefore those experiments are best captured
and described by a different term.

I examine the Puy-de-Dome experiment by Blaise Pascal and his brother
in law Florin Perier, whereby a "continuous experiment" was carried out
at the foot of the mountain whilst Perier ascended it, in order to
prove that the descent of the column of mercury carried to the top of
the mountain was unequivocally due to the higher altitude; Francesco
Redi's experiemnts on spontaneous generation, in which he placed pieces
of flesh in two containers, one covered and protected by flies and the
other open, proving that putrefying flesh does not generate insects by
itself; Redi's experiments to test the properties of a styptic water
coming from France that was advertized as a cure for dangerous arterial
wounds, in which he compared its powers to the properties of standard
water from a well; and Marcello Malpighi's experiments to establish the
role of cotyledons in the germination of seeds, whereby he argued
against Giovanni Battista Trionfetti that growth is hindered or delayed
by the removal of cotyledons compared to the case when the cotyledons
are retained.

These cases range from the physico-mathematical disciplines to natural
history and medicine, pointing to a growing methodological awareness
about experimental procedures and to a concern about the natural
variability of experimental results: the height of mercury in the
barometers is not always constant, some arterial wounds heal without
any intervention, etc. Together, they highlight a new awareness of the
need to rule out competing explanations for experimental results. Thus
the cases I examine represent an important chapter in the history and
philosophy of experimentation, one that has surprisingly been left at
the margins of current accounts of experimentation in the seventeenth
century.