Experiments and Observations on Electricity Made at Philadelphia in America — Context and Discussion
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Transcriber's note: Text enclosed by underscores is in italics (_italics_). In view of the difficulty of reliably distinguishing 18th-century variant spellings from typographical errors, the text has been reproduced entirely as printed.
_Philadelphia_ in _America_,
Mr. BENJAMIN FRANKLIN,
Communicated in several Letters to Mr. P. COLLINSON, of _London_, F. R. S.
Printed and sold by E. CAVE, at _St. John's Gate_. 1751. (_Price 2s. 6d._)
_It may be necessary to acquaint the reader, that the following observations and experiments were not drawn up with a view to their being made publick, but were communicated at different times, and most of them in letters wrote on various topicks, as matters only of private amusement._
_But some persons to whom they were read, and who had themselves been conversant in electrical disquisitions, were of opinion, they contain'd so many curious and interesting particulars relative to this affair, that it would be doing a kind of injustice to the publick, to confine them solely to the limits of a private acquaintance._
_The Editor was therefore prevailed upon to commit such extracts of letters, and other detach'd pieces as were in his hands to the press, without waiting for the ingenious author's permission so to do; and this was done with the less hesitation, as it was apprehended the author's engagements in other affairs, would scarce afford him leisure to give the publick his reflections and experiments on the subject, finish'd with that care and precision, of which the treatise before us shews he is alike studious and capable. He was only apprized of the step that had been thus taken, while the first sheets were in the press, and time enough for him to transmit some farther remarks, together with a few corrections and additions, which are placed at the end, and may be consulted in the perusal._
_The experiments which our author relates are most of them peculiar to himself; they are conducted with judgment, and the inferences from them plain and conclusive; though sometimes proposed under the terms of suppositions and conjectures._
_And indeed the scene he opens, strikes us with a pleasing astonishment, whilst he conducts us by a train of facts and judicious reflections, to a probable cause of those phænomena, which are at once the most awful, and, hitherto, accounted for with the least verisimilitude._
_He exhibits to our consideration, an invisible, subtile matter, disseminated through all nature in various proportions, equally unobserved, and, whilst all those bodies to which it peculiarly adheres are alike charged with it, inoffensive._
_He shews, however, that if an unequal distribution is by any means brought about; if there is a coacervation in one part of space, a less proportion, vacuity, or want, in another; by the near approach of a body capable of conducting the coacervated part to the emptier space, it becomes perhaps the most formidable and irresistible agent in the universe. Animals are in an Instant struck breathless, bodies almost impervious by any force yet known, are perforated, and metals fused by it, in a moment._
_From the similar effects of lightening and electricity our author has been led to make some propable conjectures on the cause of the former; and at the same time, to propose some rational experiments in order to secure ourselves, and those things on which its force is often directed, from its pernicious effects; a circumstance of no small importance to the publick, and therefore worthy of the utmost attention._
_It has, indeed, been of late the fashion to ascribe every grand or unusual operation of nature, such as lightening and earthquakes, to electricity; not, as one would imagine, from the manner of reasoning on these occasions, that the authors of these schemes have, discovered any connection betwixt the cause and effect, or saw in what manner they were related; but, as it would seem, merely because they were unacquainted with any other agent, of which it could not positively be said the connection was impossible._
_But of these, and many other interesting circumstances, the reader will be more satisfactorily informed in the following letters, to which he is therefore referred by_
Mr BENJ. FRANKLIN, in _Philadelphia_.
Mr PETER COLLINSON, F.R.S. _London_.
THE necessary trouble of copying long letters, which perhaps when they come to your hands may contain nothing new, or worth your reading (so quick is the progress made with you in Electricity) half discourages me from writing any more on that subject. Yet I cannot forbear adding a few observations on M. _Muschenbroek_'s wonderful bottle.
1. The non-electric contain'd in the bottle differs when electrised from a non-electric electrised out of the bottle, in this: that the electrical fire of the latter is accumulated _on its surface_, and forms an electrical atmosphere round it of considerable extent: but the electrical fire
This volume collects Benjamin Franklin's letters and papers on electricity, written in Philadelphia between 1747 and 1750 and sent to Peter Collinson in London. The preface explains that the material was never intended for publication; it was printed only after being shown to others “conversant in electrical disquisitions,” who urged its release. The result is a work that retains the informal, epistolary character of scientific correspondence, with Franklin proposing hypotheses, describing experiments, and refining his ideas in successive letters.
Franklin's central concept—that electricity is a single fluid that can be transferred between bodies, leaving one deficient (negative) and the other surcharged (positive)—emerges through concrete observations. He describes how a shock from a “large glass jar” passes through the body, and compares common matter to a “spunge” that absorbs electrical fluid. These analogies ground his theorizing in everyday experience.
From Private Amusement to Published Letters
The preface reveals that Franklin's experiments were originally “matters only of private amusement.” An unnamed editor assembled the letters and “detach'd pieces” without Franklin's prior permission, only informing him when the first sheets were already in press. Franklin then supplied “some farther remarks, together with a few corrections and additions,” placed at the end. This publication history shapes the text's structure: it is not a unified treatise but a series of communications, each responding to questions or reporting new findings. Readers encounter Franklin's ideas as they developed, with occasional afterthoughts and corrections appended.
The Electrical Fluid as a Universal Substance
Franklin's opening “Opinions and Conjectures” (1749) lays out his theory in numbered propositions. He defines electrical matter as “particles extreamly subtile” that can permeate even the densest metals. The particles repel each other but are “strongly attracted by all other matter.” This dual behavior explains why an electrified body's excess fluid forms an “electrical atmosphere” on its surface. Franklin then draws an extended analogy: common matter is “a kind of spunge to the electrical fluid,” absorbing it until saturated. The comparison is detailed—he considers pore size, attraction, and repulsion among fluid particles—showing his method of reasoning from familiar phenomena to invisible processes.
Speculative Uses and Cautions
Franklin acknowledges that “the beneficial uses of this electrical fluid in the creation, we are not yet well acquainted with,” though he suspects they are “very considerable.” He then speculates on the dangers of an excess: if the Earth contained as much electrical matter proportionally as a charged iron globe, “the particles of dust and other light matters” would repel each other, with potentially disruptive effects. This passage illustrates Franklin's willingness to extrapolate from laboratory experiments to cosmic scales, while remaining cautious about claiming certain knowledge. The conjectural tone is typical of the collection, which presents hypotheses as “suppositions and conjectures” rather than established facts.
Because the text is a compilation of letters, readers may find it helpful to track Franklin's evolving terminology—for instance, his shift from describing electricity as a fluid to using the terms “positive” and “negative.” The appended corrections and additions at the end should be consulted alongside the main letters, as they contain Franklin's later refinements. This edition reproduces the original 18th-century spelling and punctuation, which can occasionally obscure meaning but preserves the historical character of the work.
Franklin’s letters to London feel like watching a bright, patient mind feeling its way in the dark. That same quiet wonder lives in Faraday’s own notebooks, as if both men knew electricity was never quite theirs to command, only to befriend. A kinship of gentle curiosity, I think. Michael Faraday, His Life and Work — Themes and Context keeps such good company on my shelf.
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