While reading S.C. Tiwari's book, Superluminal Phenomena in Modern
Perspective (Rinton Press) [www.RintonPress.com/books/tiwari.html],
and recognizing that Dr. Tiwari has done a tremendous amount of
research on tachyons, I noticed that he attributes the first mention
of any kind of object resembling faster-than-light (FTL) particles
(not yet named "tachyons") to a mathematician named Le Sage, who is
alleged to have come up with the idea that "corpuscles" traveling FTL
could be used to explain Classical gravitaton (in Tiwari's book, see
page 6, Chapter 1, in Section 1.1, entitled "Historical Note").
There is some debate, however, on whether Le Sage or a Frenchman
named de Dullier originated the theory called "Le Sage gravity".

Here's the scoop on Le Sage's theory of gravitation (mostly cut-and-
pasted from Wikipedia, but with some editing of my own).

In 1690 Nicolas Fatio de Duillier of France, and in 1782 Georges-
Louis Le Sage of Geneva, proposed independently a kinetic theory for
gravity, which offered an explanation for Newton's force equation.
However, because Fatio's work was not widely known and remained
unpublished for a long time, it was Le Sage's exposition of the
theory that became popular, and which also became the subject of
renewed interest in the late nineteenth century when it was studied
in the context of the then newly discovered kinetic theory of gases.

By the early twentieth century, the theory was generally considered
discredited, most notably due to issues raised by James Clerk Maxwell
and Henri Poincare. Today, while Le Sage's theory is still studied
by some researchers (such as physics historians), it is not regarded
as a viable theory within the mainstream scientific community.

Referred to as "LeSage gravity", the idea is that the universe is
filled with "mundane courpuscles" that travel faster-than-light in
all directions; imparting the same amount of collisional force from
every direction on every isolated object. But when two objects are
fairly close to one another, they get shielded by each other, so that
there is less force on the sides that face each other, which results
in the forces on the unshielded sides pushing the objects towards
each other; the total amount of force given by Newton's formula.

With the advent of Maxwell's objections, and the success of his
equations explaining electromagnetism (and since no "mundane
corpuscles" had ever been observed), Le Sage gravity lost out to the
assumption that there was instead a gravitational field, and that it
was analogous to the electromagnetic field, except that instead of a
dipole field (having two poles, each on opposite ends of a central
axis), gravity was rather a quadrupole field (having two sets of such
poles, and therefore two central axes, oriented at right angles to
each other). This, indeed, remains the assumption among many modern
researchers, of how quantum gravity works; despite the fact that
there is no unbiased experimental justification for it.

For the complete Wikipedia reference, go to
http://en.wikipedia.org/wiki/Le_Sage's_theory_of_gravitation

I find it intersting, in any case, that one of the first explanations
of Newtonian gravity involving particles suggests particles traveling
faster-than-light, which, by the way, was compatible with Newton's
own vision of how the gravitational force was imparted. And this
appears to be the first suggestion on the possible existence of
faster-than-light particles altogether.

Newton, by the way, did not originate, nor endorse, the concept of
instantaneous "action at a distance" that came to be attached to his
formulation of gravity (first by an Englishman named Cotes, then by
nearly everyone else), and which implies an infinite-speed mediator.
To the contrary, he believed in an aether that pervades all of space,
and that an "agent" of some kind, propagating through the aether with
a finite speed, was the mediator of the force (although Newton also
did not take a stance on exactly how fast this agent acted).

It is interesting to note that Einstein's understanding of gravity,
the theory of General Relativity (GR), did not dismiss Newtonian
gravity, but incorporates it as a special case. In fact, GR retains
Newton's universal gravity constant (~6.67x10^-11 N m^2 / kg^2), and
is reported in many sources (and confirmed simply by doing the math)
to be equivalent to Newton's gravity at what is called the "weak
field limit" of GR. And, though others (starting with Lorentz) set
the speed of gravity at the speed of light, c, based on the fact that
the electromagnetic field propogates at c (and most scientists were
assuming that gravity was analgous to electromagnetism, which made no
sense if gravity was instantaneous), this notion remains attached to
the pseudo-Riemannian equations of GR in many people's minds, despite
not formally being required in Einstein's original formulation of GR.

Since I have developed an hypothesis that certain special kinds of
tachyons can be used to explain quantum gravity, then I looked into
Le Sage's theory, but found it unsatisfactory. Clearly, he was on
the right track. But without a knowledge of Einstein's Relativity or
of Quantum Theory, he did the best he could. However, I also find
unacceptable the long-standing assertion that gravity is a quadrupole
analog of electromagnetism, mediated by a spin-2 massless "graviton".

I am of the opinion that the type of tachyon I describe in my thesis
on gravity explains quantum gravity in a way that is compatible both
with GR and with Newton's vision, that it fits with all uncorrupted
experimental data we have on gravity (and better than any other kind
of exchange-particle so-far proposed for gravity), and that it is
also an empirically valid force mediator, which I contend is soon to
be proven beyond doubt experimentally. [Indeed, sometime this year.]

For a brief version of my thesis, click "Tachyonic Gravity", at
www.TachyonicsSociety.com

And, for an overview of the latest experimental efforts focusing on
determining the most accurate theory of quantum gravity, see Lee
Smolin's article "Quantum Gravity Faces Reality", in the November
2006 issue of Physics Today magazine, page 44.

Stay tuned.