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On the origin of the Korteweg-de Vries equation

History and Overview · Submitted 28 Feb 2006 · 31 references

Pith's verdict: A mathematically sound historical essay whose central attribution claim—Boussinesq wrote KdV avant la lettre—needs primary-source verification, but the derivation and the comparison of boundary conditions are genuinely useful.

T0 · AI review

How this review was made: An AI referee (deepseek-v4-flash) read the paper on August 28, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

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  4. T3 Formal statement The claims written out in a formal math language a computer can read.
  5. T4 Proof Those claims proved, and the proof checked by computer.

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arXiv IDmath/0602661 (version 2)
Pith IDKEUMHJ4R, Pith's permanent record of this paper and its review
CitationE. M. de Jager. "On the origin of the Korteweg-de Vries equation." arXiv:math/0602661 (2006). https://pith.science/paper/KEUMHJ4R
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Referee report
The paper

The paper claims

The Korteweg-de Vries equation was already in Boussinesq's 1872 equations, waiting on a substitution he never performed.

The reading

The paper argues that the Korteweg-de Vries equation was already within Boussinesq's reach in the early 1870s: substituting his expression for the wave velocity into his continuity equation turns his 1872 shallow-water equations into the KdV equation. It also reports that the same equation appears explicitly in a footnote in Boussinesq's 1877 memoir, well before the 1895 paper that gave the equation its customary name. The reason to care is historical and conceptual: it separates who first wrote an equation from who first gave it a usable range of validity. The paper stresses that Korteweg and De Vries's real contribution was a unified treatment covering both solitary waves that die out at infinity and periodic waves, whereas Boussinesq's version carries the vanishing-at-infinity assumption.

What carries the argument

At the center is a substitution identity. Boussinesq's continuity equation (4.5), $\frac{\partial h}{\partial t} + \frac{\partial}{\partial x}(\omega h) = 0$, together with his pointwise wave velocity (4.8), $\omega = \sqrt{gH} + \sqrt{gH}\left(\frac{3h}{4H} + \frac{H^2}{6h}\frac{\partial^2 h}{\partial x^2}\right)$, yields (4.11), $\frac{\partial h}{\partial t} + \sqrt{\frac{g}{H}}\,\frac{3}{2}\,\frac{\partial}{\partial x}\left(\frac{2}{3}Hh + \frac{1}{2}h^2 + \frac{H^3}{9}\frac{\partial^2 h}{\partial x^2}\right) = 0$, which is the KdV equation. The paper also invokes the auxiliary function $\psi_1$ from the 1877 footnote, and the factorization (4.12) of the bidirectional Boussinesq equation into two KdV-type factors. These algebraic moves are what convert a historical comparison into an equivalence of equations.

Extended reading notes

Core claim

On the paper's own terms, Boussinesq's analysis contains the KdV equation twice, in two different senses. First, the displayed equations (4.5) and (4.8) of his 1872 article combine by direct substitution into equation (4.11), which is the Korteweg-de Vries equation in a fixed coordinate frame; Boussinesq did not make that substitution. Second, according to the paper, a footnote on page 360 of the 1877 'Essai sur la théorie des eaux courantes' effectively writes out the KdV equation via an auxiliary function $\psi_1$, a fact recovered only in the modern historical literature. The paper adds that the bidirectional Boussinesq equation factorizes into two unidirectional factors, one of which is KdV, as shown in equation (4.12). What Korteweg and De Vries added was not the equation itself but a derivation that avoids the vanishing-at-infinity assumption, so the same equation governs periodic cnoidal waves as well as solitary waves.

Load-bearing premise

The historical-priority claim depends on the report that Boussinesq's 1877 footnote actually writes out the Korteweg-de Vries equation; if that report is wrong, the algebraic derivation from his other equations still stands, but the claim of an explicit earlier statement does not.

Editorial extensions

If this is right

  • If the substitution is legitimate, Boussinesq's 1872 article contains the KdV equation in unidirectional form, and his 1877 memoir contains it explicitly in a footnote; the customary name is then a matter of historical reception rather than first derivation.
  • The 1895 Korteweg-de Vries equation is equivalent to Boussinesq's solitary-wave theory when surface tension is neglected; the remaining difference is the choice of a fixed versus a moving coordinate frame.
  • Because the bidirectional Boussinesq equation factorizes into two unidirectional factors, the KdV equation can be read as one half of a more general two-directional shallow-water model.
  • Korteweg and De Vries's distinctive contribution is the removal of the vanishing-at-infinity assumption, which lets one equation govern both solitary waves and periodic cnoidal waves; Boussinesq treated periodic waves separately.
  • Boussinesq's conserved 'moment de stabilité' appears inside a Hamiltonian formulation of the KdV equation, so his stability argument anticipates the later Hamiltonian theory of integrable wave equations.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • A reader can infer that the equation's name is partly a historical accident: had the 1877 footnote been incorporated into the standard narrative earlier, the central object of soliton theory could plausibly be called the Boussinesq equation.
  • The paper's method—checking whether a displayed equation in an older memoir turns into a later equation by a simple substitution—offers a general historiographic test, provided one also checks the validity conditions under which the two equations live.
  • A natural follow-up question, beyond the historical claim, is how much of the KdV equation's integrable structure (soliton collisions, infinite conservation laws) is visible already in the bidirectional Boussinesq equation from which KdV factors out.
Original abstract

The Korteweg-de Vries equation has a central place in a model for waves on shallow water and it is an example of the propagation of weakly dispersive and weakly nonlinear waves. Its history spans a period of about sixty years, starting with experiments of Scott Russell in 1834, followed by theoretical investigations of, among others, Lord Rayleigh and Boussinesq in 1871 and, finally, Korteweg and De Vries in 1895. In this essay we compare the work of Boussinesq and Korteweg-de Vries, stressing essential differences and some interesting connections. Although there exist a number of articles, reviewing the origin and birth of the Korteweg-de Vries equations, connections and differences, not generally known, are reported.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 3,735 input tokens.

What the abstract itself states, as probabilities: claims first 0.05 · states limitation 0.13 · human participants 0.03 · controlled comparison 0.03 · randomized assignment 0.01 · states quantitative result 0.16 · compares with prior results 0.54 · mentions code or data availability 0.01.

The abstract, sentence by sentence

arXiv listing abstract v2. Results and the main claim are underlined; .

The Korteweg-de Vries equation has a central place in a model for waves on shallow water and it is an example of the propagation of weakly dispersive and weakly nonlinear waves. Its history spans a period of about sixty years, starting with experiments of Scott Russell in 1834, followed by theoretical investigations of, among others, Lord Rayleigh and Boussinesq in 1871 and, finally, Korteweg and De Vries in 1895. In this essay we compare the work of Boussinesq and Korteweg-de Vries, stressing essential differences and some interesting connections. Although there exist a number of articles, reviewing the origin and birth of the Korteweg-de Vries equations, connections and differences, not generally known, are reported.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 The Korteweg-de Vries equation has a central place in a model for waves on shallow water and it is an example of the propagation of weakly dispersive and weakly nonlinear waves. background 1.00 0.05 0.04 asserted 1.00
s1 Its history spans a period of about sixty years, starting with experiments of Scott Russell in 1834, followed by theoretical investigations of, among others, Lord Rayleigh and Boussinesq in 1871 and, finally, Korteweg and De Vries in 1895. background 1.00 0.03 0.03 asserted 1.00
s2 In this essay we compare the work of Boussinesq and Korteweg-de Vries, stressing essential differences and some interesting connections. contribution 1.00 0.72 0.09 asserted 0.91
s3 Although there exist a number of articles, reviewing the origin and birth of the Korteweg-de Vries equations, connections and differences, not generally known, are reported. gap 0.66 0.57 0.12 asserted 0.99

What kind of paper the classifier reports this is: review 0.91 · evidence from literature 0.97.

What was examined, and what was not

sources read
  • arXiv listing abstract v2
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures
Figure 1. Scott Russell’s experiments For an extensive historical study the reader may consult the papers by Bul￾lough [14] and Darrigol [17]. As mentioned in the introduction, there existed in England and France a rich tradition in the mathematical description of hydrody￾namic phenomena such as wave motions in fluids. Scott Russell challenged the mathematical community to prove theoretically the existence of his solitary wave and “to give an a priori demonstration a posteriori” i.e. to show the possible existence of a stable solitary wave propagating without change of form. It is not unusual…
Figure 2. Wavesurface The coordinates of a fluid particle are given by the coordinates x and y, the undisturbed depth of the canal by the constant H and the wave surface by H + h(x, t). Another essential assumption is that the wave length is large in comparison with H. As has been mentioned in the preceding section, Airy had already remarked that the theory of shallow waves of great length is contained in the equation ∂ 2X ∂t2 = gκ ∂ 2X ∂x2 (where κ = H and g the constant of gravity). The wave velocity is √ gκ , a result generally known since Lagrange in 1786. However, this result is on
Figure 3. Cnoidal Wave Suppose now that the minimum value h0 of h, which is necessarily negative, is assumed at x = 0 and the wave surface represented by h˜(x, t) = h(x, t) − h0, then h˜ ≥ 0 and h˜ = 0 at x = 0. This shift results into

Figures reproduced from arXiv:math/0602661 by the authors.

References
How the literature uses it

4 arXiv papers cite this in 4 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it

Cites it as background 4 papers

Discussion

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