Mysterious old letter

[From Bill Powers (951119.1930 MST)]

Letter found in a basement of the British Museum, apparently a
translation but from what language is not known.

My Esteemed Sir Isaac Newton,

I have read with interest your pioneering works on gravitation and the
properties of motion. It seems to be the best treatment of projectiles
and falling objects that has been offered so far. My own interest has
been in the uses of seige guns and (historically) catapults, with
particular emphasis on the effects of clouds, nearby bodies of water,
dry and moist winds, swamp humours, and moonlight on the impetus
exhaustion point, or IEP (the point where the initial impetus, or as you
call it the "tendency to continue in a state of motion", is exhausted
and the projectile falls straight down). Your theory of universal
gravitation is entirely consistent with what is known about these
matters, and expresses observations of this kind very succinctly.

I am somewhat puzzled that you have not mentioned the IEP; it has been
the subject of numerous treatises published in _Ballistica_ over the
past twenty years, with a great deal of work relating the IEP to
important natural principles of earth, air, fire, and water (my own
specialty concerns the effects of water, on which I have written several
books that are standards in the field). In fact, it seems to me that
your predictions are somewhat in error, as they seem to result in smooth
trajectories in which the IEP is all but undetectable. If you will
permit a suggestion, I hope you will consider the measurement techniques
described in numerous articles in _Ballistca_, particularly the
essential corrections for optical illusions that I have developed and
which your mathematical expressions, I am told, do not include. You may
find that my own field, in some small measure, may help you in your work
as much as I expect your work to help mine. I will be happy to transmit
copies of relevant works to you, if you wish to see them.

While your work is an important advance in our understanding of
affinities, proclivities, and tendencies of natural bodies to move in
various ways, I have been disappointed to see that you have ignored a
number of basic phenomena (Some of my colleagues, indeed, consider your
speculations about gravitational effects on the Moon and planets to be
rather frivolous, as there is no possible way of testing them). I
realize that you have a great deal to do in carrying out your official
duties, but if your work is to be considered in any sense complete,
there are important topics that it must include. For example, you have
said nothing about the trajectories of birds and insects, nor those of
leaping fish or falling raindrops, and you have not considered the
puzzling phenomena of clouds, hot-air balloons, and rising smoke, which
clearly involve both fire and air and a reversal of the natural affinity
of dense objects for earth and water.

I am currently working on a treatise that explains these anomalous
phenomena in terms of your theory of gravitation, with the introduction
of a compensating "gravitational oversufficiency" effect which, for
objects with a natural preference for air or fire, just balances out the
otherwise universal gravitational effect. You and I are really talking
about the same thing, of course, although in different contexts.

While writing this, I have realized (inspired by your wonderful work)
that you should find a great deal in common with the revered Aristotle,
and that by taking into account some of his findings you might resolve
the disparity between your predictions and the phenomena associated with
the Impetus Exhaustion Point. Aristotle found that certain objects in
flight are maintained in motion by air displaced by their passage and
returned in a vortex to their rear surfaces, where the air imparts a
continued forward motion to them. By combining his observations with
your mathematics, you might be able to show that Aristotle's effect
could mask the occurrance of the IEP under some circumstances, carrying
the projectile beyond the IEP in an apparent but spurious continuous
arc. Most projectiles, of course, cease to move at the IEP and move
along the line of greatest affinity to the Earth (or Water), but I am
sure that there will be cases where the Newton-Aristotle effect could be
detected by careful measurement. I hope you will devote at least some of
your time to working out the details of this proposal now that I have
provided the basic approach.

Before I bid you farewell, I must say how entertained I have been by
your experiments with prisms and sunlight. Who would have thought that
Fire could stimulate mere glass to emit emanations of just the colors
that signify earth, air, and water? An astonishing discovery, Sir Isaac;
I confess that I don't know what to make of it yet. I'm thinking of
firing some large prisms from a cannon (on a sunny day) to see whether
they show the same IEP as projectiles made of opaque materials.

With respect and admiration, I remain


(signature illegible)