How Halley Saved The Principia from Swimming with the Fishes


Space fish. Taken from

The French deserve a round of applause for their linguistic savvy. I, for one, salute and empathize with their decision to closely connect death with fishes using the sound Z. You see, the French word for fish is poisson (pronounced pweh-ssson; articulation should be fast and French), and poison is poison – not much of a spelling difference there if you look really closely, but its pronunciation is aggressive and the Z is strong where the S is placed. This lexical linkage serves as a nasty but important personal reminder of that time when I almost died of asphyxiation: Five-year old me felt thorns in my throat when a piece of bone from a grouper decided to edge me close to death during dinner.

Completely metaphorical, that if you take an S (skeleton) from poisson, it turns into the lethal libation poison.

Oh, it is just one of those French things the French say! some will argue – how far from the truth! In fact, the relationship of death with fishes finds home in many linguistic and literary domains. We read in Mario Puzo’s The Godfather that Luca Brasi’s death is announced by an ominous fish. Achilles, master murderer in Homer’s Iliad, in a fit of vengeful violence takes Lycaon on a trip of unimaginable torment, and just as they were about to reach the final stop, Achilles tells him to “Make your bed with the fishes now.”

(Disclaimer: Before any of you claim that this is just one man’s struggle in coming to terms with his traumatic past, let me assure you that I have no problem with fishes at this point in my life, just as long as they are in a sashimi or fillet format.)

Perhaps I am just grossly exaggerating the gravity of this connection. That may be the case. But history is fishy, and if we dig down its scales, we find proof that the poison of poisson almost drowned mankind’s first mathematical attempt to detail the workings of gravity.

It all started with a very English banter and bet bearing the premise of a bad comedy: Three Royal Society fellows walk into a bar. . .

Their names were Edmond Halley, Robert Hooke, and Christopher Wren. One of them is best remembered as a comet, another as a bird, and the other as a pirate. But these designations are unfair. The three were no ordinary fellows, they were scientific titans of their time.


Portrait of Edmond Halley by Thomas Murray, c.1687

They engaged in a discussion circling around the elliptical nature of planetary orbits. Johannes Kepler had provided the laws stating so: Planets do not revolve around the sun in perfect Galilean circles. Their paths, when traced, closely resemble a circle squished softly on two of its opposite sides. What directed planetary elliptical trajectory was obedience to the inverse square law. The problem was on the questions why and how. To solve the issue, mathematics was necessary, and the three of them were no hacks in that department. Robert Hooke took to announce his lead in the matter by confirming the works of the inverse square law, yet, refused to divulge any mathematical proofs, claiming that he would wait until the other two also arrived at the same results. Christopher Wren, not relenting to the bluff, offered a bet and prize worth 40 shillings to anyone who could come up with the correct mathematical proof within the next two months.

Game on.

Two months had passed and no one got around to prove it. Perhaps all three forgot, or maybe they just could not do it. But Halley somehow remembered and set himself the task of consulting England’s arch-mathematician regarding the matter. He boarded a coach and found himself deposited in Trinity College, Cambridge in 1684, the scholastic stronghold of Isaac Newton. When the niceties and courtesies were dispensed, Abraham de Moivre recounts that Halley wasted no time to ask Newton what kind of curve will a planet’s trajectory be if we suppose “the force of attraction towards the Sun to be reciprocal to the square of their distance from it.” Newton immediately responded that it would be an ellipse. This confirmation set Halley’s heart ablaze and he excitedly prodded Newton to tell him how he arrived at that conclusion. Newton simply said, “I have calculated it.” From two months of nothing, followed by periods of stagnation, here came the moment of reckoning. It might have been too late to win the bet, but Halley was seeking answers on a purely scientific enterprise – prize or no prize. But dismay suddenly bolted in unannounced, as Newton could not find the papers where he wrote his calculations. It almost seemed like Halley went full circle and found himself back to where he started, empty handed. Fortunately, Newton was willing to redo his calculations and promised to send it to Halley upon completion.


Isaac Newton by Godfrey Kneller, c.1689

Fast forward to December of that year, in one of the regular Royal Society meetings: Halley had received from Newton a nine-page treatise titled De motu corporum in gyrum (On the Motion of Bodies in Orbit) the month before and was in no mood to delay the announcement of its findings. Here it is! The answer to all our questions! he must have said, knowing the revolutionary implications the paper contained. In the December meeting, he announced to the society that Newton had shown him this remarkable treatise that was of utmost scientific importance. Thing is, Halley said, Newton was still expanding the ideas he laid out on the treatise – so the society had to wait for his complete exposition on the matter. No worries though, for Newton promised Halley that he would send the society a copy of it once he was done.

For 18 months Newton worked feverishly to finish the monumental task. He kept corresponding with John Flamsteed, Britain’s Astronomer Royal, for astronomical data so he could finesse his calculations; data which, he tells Flamsteed, “gives me very much satisfaction”. Finally, the manuscript arrived at the society’s doorsteps in April 1686. It was an “extension” one would expect of Newton: from a mere nine-page treatise, he produced an expanded version stretching to three volumes bearing the title Philosophiae Naturalis Principia Mathematica or simply known as the Principia. It was a scientific storm caged in pages and trapped in leather spine – the next step was to unleash it.

Trouble was, the society made a bit of a blunder.

While Newton was taming his thunder, the society set loose upon the public De Historia Piscium (The History of Fish). The book’s subject alone should be indicative of its effect on Principia.

De Historia Piscium was a project of Francis Willughby who took upon himself the task of cataloging all the known fishes at that time with accompanying drawings and sketches. He died before the book saw publication (a strong case for poisson = poison?). His close colleague and mentor John Ray took over the task and once finished had the Royal Society sponsor it for printing. De Historia Piscium was released in 1686.



Title page of Willughby’s De Historia Piscium. Illustration by Paul van Somer

The book was an ornate piece of work that required expensive plates for the elaborate illustrations of its sea-creatures. Expectations were high and the society thought that this would be a success thanks to its grand scheme and evocative aesthetics.

It was not.

De Historia Piscium was a financial disaster, an investment gone wrong. Clueless on how to deal with this commercial failure, the society was desperate to move copies to booksellers and individual subscribers – they even sent it for free to dignitaries and galleries.  As a result, the society was low on cash and its coffers were close to getting empty. Worst, on their hands was the manuscript of the Principia, but they had no means to have it sent to the printers for publishing.

Until Halley came to the rescue.

The Royal Society employed Halley as its clerk in 1685. He was assigned to deal with the society’s finances and the publication of its Philosophical Transactions (one of the major source of income of the society). And it was on him that the problem of publishing Newton’s Principia fell – a task that he would see through without fail, albeit with disheartening and hilarious consequences.

Halley saved the Principia from sleeping with the fishes by using his own salary as bait to reel it back to safety. It was decided in a June 1686 society meeting that Newton’s manuscript “be printed, and that Mr. Halley undertake the business of looking after it, and printing it at his own charge, which he engaged to do”. But as Halley reeled back the Principia, thinking that he was already off the hook, the fishes scaled back on board to deal one last irony.

As the society’s clerk, Halley’s wages amounted to 50 pounds annually. Not much compared to the annual earnings of merchants and other men of business at that time. But it was enough for Halley, nonetheless. Upon the release of the Principia in July 1867, the society pondered on the issue of Halley’s salary.

Having spent his own cash for the Principia’s publication, Halley surely needed some money to recover from the expenses he incurred. What shall we give this man as compensation for all his troubles? the society asked itself. Looming in the air was a kind of stench, a certain wet and scaly scent. The society looked around trying to trace the origin of the odor, it then found a stack of books lying unused on the shelves: copies of De Historia Piscium. The society had an idea.

Halley: Wait a minute!

The Royal Society: ( ͡° ͜ʖ ͡°)

On the question, “whether E. Halley should have 50 of the books of Fishes, instead of the fifty pounds ordered him by the last Councell”, the society saw it fit to conclude in the affirmative. Moreover, as a testimony of their utmost gratitude for his selfless service of pulling the society out of a sticky wicket, the society decided that Halley shall “receive a gratuity of twenty other books de Piscibus in consideration of his services”.

Halley, 50 pounds poorer, was at least 70 books of fishes richer by the end of this episode. At least, through the silly circumstances that befell him, what he considered as a “divine treatise” was published for the world to enjoy. No word of regret seemed to have come from Halley after this debacle. Instead, he peppered nonstop paean and praise on Newton’s work: The Principia, a book that Halley claimed to have “set out the pattern of the Heavens!” That with its light, “No longer does error oppress doubtful mankind with its darkness”, and as such, mankind has earned entry to the divine kingdom because “the keenness of a sublime Intellect has allowed us to penetrate the dwellings of the Gods”. More than just being an entry pass, Newton’s Principia is also mankind’s invitation card to a divine dinner party, as its publication meant that “we are truly admitted as table-guests of the Gods”. Who would like to lead the saying of grace?

The combination of Newton’s findings and Halley’s persistence led the way for a revolution in scientific thought. What Newton illuminated was a clearer understanding of how things, astronomical and trivial and everything in between, happen: why on earth are seat belts important, why cannot flying fish remain airborne, why did the apocryphal apple fall on Newton’s head, why are cats amazing, why are planets moving around the sun; all these are made a little easier to answer thanks to Newton (and of course Halley, who persuaded him to pursue this undertaking). Perhaps it will indeed lead us to God’s dinner table in the near future.

Hopefully, God has no particular fondness for fish.



A first edition copy of the Principia. Happily, this book sleeps in Trinity College’s Wren Library (away from fishes!).



Cook, Allan. Edmond Halley: Charting the heavens and the seas. Oxford: Oxford University Press. 1998

Wakefield, Julie. Halley’s quest: a selfless genius and his troubled paramore. Washington, DC: Joseph Henry Press. 2005

Westfall, Richard. Never at rest: a biography of Isaac Newton. Cambridge: Cambridge University Press. 1983

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