Lightning, Thunder and Lightning Conductors — Inside the Classic

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Authors: Molloy, Gerald, 1834-1906 Digital Source: Project Gutenberg Gutenberg Release Year: 2022 First Publication Year: Not confirmed

Key Word: Lightning; Lightning conductors; Thunderstorms Target Reader: Readers of public-domain and historical texts

Book Edition: Project Gutenberg digital edition Book Language: en

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Words 30,560

Reading time 133 min

Text sections 9

This digital edition of Lightning, Thunder and Lightning Conductors — Inside the Classic is described by source-level measurements including 30,560 words, 2 hr 13 min estimated reading time, and 9 detected text sections.

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Source: Project Gutenberg record #68994

Gerald Molloy's 1890 lecture-based work examines lightning's physical properties, thunder's acoustics, and the design of lightning conductors, with an appendix on the 1888 British Association debate. Structured as two lectures and a controversy summary, it uses experiments and historical examples to explain electrical phenomena.

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LIGHTNING CONDUCTORS.

_WITH AN APPENDIX ON THE RECENT CONTROVERSY ON LIGHTNING CONDUCTORS._

GERALD MOLLOY, D. D., D. Sc.

THE HUMBOLDT PUBLISHING CO.,

LIGHTNING, THUNDER, AND LIGHTNING CONDUCTORS.

LECTURE I. Pages 5-26

LIGHTNING AND THUNDER.

Identity of Lightning and Electricity--Franklin’s Experiment--Fatal Experiment of Richman--Immediate Cause of Lightning--Illustration from Electric Spark--What a Flash of Lightning Is--Duration of a Flash of Lightning--Experiments of Professor Rood--Wheatstone’s Experiments--Experiment with Rotating Disc--Brightness of a Flash of Lightning--Various Forms of Lightning--Forked Lightning, Sheet Lightning, Globe Lightning--St. Elmo’s Fire--Experimental Illustration--Origin of Lightning--Length of a Flash of Lightning--Physical Cause of Thunder--Rolling of Thunder--Succession of Peals--Variation of Intensity--Distance of a Flash of Lightning

LECTURE II. Pages 26-53

LIGHTNING CONDUCTORS.

Destructive Effects of Lightning--Destruction of Buildings--Destruction of Ships at Sea--Destruction of Powder Magazines--Experimental Illustrations--Destruction of Life by Lightning--The Return Shock--Franklin’s Lightning Rods--Introduction of Lightning Rods into England--The Battle of Balls and Points--Functions of a Lightning Conductor--Conditions of a Lightning Conductor--Mischief Done by Bad Conductors--Evil Effects of a Bad Earth Contact--Danger from Rival Conductors--Insulation of Lightning Conductors--Personal Safety in a Thunder Storm--Practical Rules--Security Afforded by Lightning Rods

APPENDIX. Pages 55-62

RECENT CONTROVERSY ON LIGHTNING CONDUCTORS.

Theory of Lightning Conductors Challenged--Lectures of Professor Lodge--Short Account of his Views and Arguments--Effect of Self-Induction on a Lightning Rod--Experiment on the Discharge of a Leyden Jar--Outer Shell only of a Lightning Rod Acts as a Conductor--Discussion at the Meeting of the British Association, September, 1888--Statement by Mr. Preece--Lord Rayleigh and Sir William Thomson--Professor Rowland and Professor Forbes--M. de Fonvielle, Sir James Douglass, and Mr. Symons--Reply of Professor Lodge--Concluding Remarks of Professor Fitzgerald, President of the Section--Summary Showing the Present State of the Question

LIST OF ILLUSTRATIONS.

THE ELECTRIC SPARK: A TYPE OF A FLASH OF LIGHTNING, 8

CARDBOARD DISC WITH BLACK AND WHITE SECTORS; AS SEEN WHEN AT REST, 12

SAME DISC; AS SEEN WHEN IN RAPID ROTATION, 12

THE BRUSH DISCHARGE, ILLUSTRATING ST. ELMO’S FIRE, 17

ORIGIN OF SUCCESSIVE PEALS OF THUNDER, 22

VARIATIONS OF INTENSITY IN A PEAL OF THUNDER, 24

DISCHARGE OF LEYDEN JAR BATTERY THROUGH THIN WIRES, 27

GLASS VESSEL BROKEN BY DISCHARGE OF LEYDEN JAR BATTERY, 32

GUN COTTON SET ON FIRE BY ELECTRIC SPARK, 33

VOLTA’S PISTOL; EXPLOSION CAUSED BY ELECTRIC SPARK, 34

THE RETURN SHOCK ILLUSTRATED, 35

PROTECTION FROM LIGHTNING BY A CLOSED CONDUCTOR, 48

INDUCTION EFFECT OF LEYDEN JAR DISCHARGE, 56

LIGHTNING AND THUNDER.

The electricity produced by an ordinary electric machine exhibits, under certain conditions, phenomena which bear a striking resemblance to the phenomena attendant on lightning. In both cases there is a flash of light; in both there is a report, which, in the case of lightning, we call thunder; and, in both cases, intense heat is developed, which is capable of setting fire to combustible bodies. Further, the spark from an electric machine travels through space with extraordinary rapidity, and so does a flash of lightning; the spark follows a zig-zag course, and so does a flash of lightning; the spark moves silently and harmlessly through metal rods and stout wires, while it forces its way, with destructive effect, through bad conductors, and it is so, too, with a flash of lightning. Lastly, the electricity of a machine is capable of giving a severe shock to the human body; and we know that lightning gives a shock so severe as usually to cause immediate death. For these reasons it was long conjectured by scientific men that lightning is, in its nature, identical with electricity; and that it differs from the electricity of our machines only in this, that it exists in a more powerful and destructive form.

=Identity of Lightning and Electricity.=--But it was reserved for the celebrated Benjamin Franklin to demonstrate the truth of this conjecture by direct experiment. He first conceived the idea of drawing electricity from a thundercloud in the same way as it is drawn from the conductor of an electric machine. For this purpose he proposed to place a kind of sentry-box on the summit of a lofty tower, and to erect, on the sentry-box, a metal rod, projecting twenty or thirty feet upward into the air, pointed at the end, and having no electrical communication with the earth. He predicted that when a thundercloud would pass over the tower, the metal rod would become charged with electricity, and that an observer, stationed in the sentry-box, might draw from it, at pleasure, a succession of electric sparks.

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Gerald Molloy's Lightning, Thunder and Lightning Conductors (1890) opens not with a definition but with a demonstration: the identity of lightning and electricity is established through Franklin's kite experiment and Richman's fatal accident. The book's structure—two lectures followed by an appendix on a contemporary scientific controversy—mirrors its dual purpose: to explain fundamental physics and to intervene in an ongoing technical debate. Molloy, a Dublin physicist and cleric, writes in a voice that shifts between lecture-hall demonstration and polemical argument, using simple apparatus like a brass chain and a rotating disc to make invisible forces visible.

From Spark to Storm: The Physics of Lightning

Molloy devotes the first lecture to lightning's physical character, drawing explicit parallels between laboratory sparks and natural flashes. He cites Professor Rood's experiments on flash duration and Wheatstone's rotating-disc method to measure the brevity of a lightning stroke. The text distinguishes three forms—forked, sheet, and globe lightning—and treats St. Elmo's fire as a brush discharge. Molloy's method is cumulative: each phenomenon is introduced with an experimental illustration before being linked to thunder's rolling peals. The lecture ends with a practical rule for estimating storm distance by counting seconds between flash and thunderclap, grounding abstract physics in everyday observation.

Destruction and Protection: The Case for Conductors

The second lecture catalogues lightning's destructive effects on buildings, ships, powder magazines, and living beings, then introduces Franklin's lightning rod as the remedy. Molloy reproduces Franklin's own instructions from Poor Richard's Almanac, noting their enduring accuracy. He emphasizes that a conductor must have adequate size and a good earth connection; a bad conductor or poor grounding can cause more harm than none. The lecture warns against 'rival conductors' and debates whether insulation is beneficial. Molloy's tone is prescriptive, offering practical rules for personal safety during thunderstorms, but he grounds each rule in the electrical principles established earlier.

The 1888 Controversy: Lodge, Self-Induction, and the Outer Shell

The appendix shifts from instruction to dispute. Molloy summarizes Professor Oliver Lodge's challenge to conventional lightning-rod theory, focusing on self-induction: Lodge argued that a lightning rod's outer shell alone conducts the discharge, and that a thick rod may be less effective than a thin one. Molloy recounts the September 1888 British Association meeting, where Preece, Lord Rayleigh, Sir William Thomson, and others debated Lodge's claims. The summary is even-handed, presenting Lodge's experiments with Leyden jars and the counterarguments of engineers like Sir James Douglass. Molloy concludes with Professor Fitzgerald's presidential remarks, leaving the question unresolved—a deliberate structural choice that turns the book into a document of scientific process.

Experiments in the Lecture Hall: How Molloy Makes Physics Visible

Throughout the text, Molloy relies on simple, reproducible demonstrations. The brass-chain experiment—where a person twenty feet away receives a shock nearly as strong as the experimenter, while someone ten feet away feels almost nothing—illustrates the return shock and the importance of electrical communication. The rotating disc with black and white sectors, used to measure flash duration, appears in the list of illustrations. These experiments are not decorative; they are the book's primary evidence. Molloy's prose often addresses an audience directly ('I hand to any one among the audience'), preserving the lecture's interactive character. This pedagogical structure allows readers to replicate the reasoning, not just the conclusions.

Molloy's book is best read as a record of late-nineteenth-century electrical science in action: a lecture course that doubles as a position paper. Readers interested in the history of physics will find a clear exposition of pre-ionization theories of lightning; those concerned with engineering will encounter the roots of modern grounding practice. The appendix, in particular, rewards attention as a snapshot of a scientific community in disagreement, before consensus hardened.

That rainy afternoon, Molloy’s thunder felt less like physics and more like a long, patient voice from another century. When I finally set the book down, I found myself thinking about other Victorian certainties—canals, for instance, and their quiet, interrupted ambitions. So I reached for British Canals: Is their resuscitation practicable? — Story, Setting & Ideas, a different kind of hopefulness entirely.