maxwell (symbol: Mx) is the CGS (centimetre-gram-second) unit of magnetic flux ( Φ). 
The unit name honours
James Clerk Maxwell, who presented a unified theory of  electromagnetism. The maxwell was recommended as a CGS unit at the International Electrical Congress held in 1900 at Paris. This practical unit was previously called a  line, reflecting  Faraday's conception of the magnetic field as curved lines of magnetic force, which he designated as  line of magnetic induction.  Kiloline (10 3 line) and megaline (10 6 line) were sometimes used because 1 line was very small relative to the phenomena that it was used to measure. 
maxwell was affirmed again unanimously as the unit name for magnetic flux at the Plenary Meeting of the International Electrotechnical Commission in July 1930 at Oslo. In 1933, the Electric and Magnetic Magnitudes and Units committee of the  International Electrotechnical Commission recommended to adopt the metre-kilogram-second ( MKS) system ( Giorgi system), and the name weber was proposed for the practical unit of magnetic flux ( Φ), subject to approval of various national committees, which was achieved in 1935. The  weber was thus adopted as a practical unit of magnetic flux by the International Electrotechnical Commission.
maxwell is a non- SI unit.  1 maxwell = 1 gauss × cm 2
That is, one maxwell is the total flux across a surface of one square centimetre
perpendicular to a magnetic field of strength one gauss.
weber is the related SI unit of magnetic flux, which was defined in 1946.  1 maxwell ? 10 -8 weber
International Bureau of Weights and Measures (2006), The International System of Units (SI) (PDF) (8th ed.), ISBN , 92-822-2213-6 archived (PDF) from the original on 2017-08-14 , p. 128
^ "as late as 1936 a subcommittee of the IEC [
International Electrotechnical Commission] proposed the names 'maxwell', 'gauss' and 'oersted' for the cgs electromagnetic units of flux, induction and magnetic field strength, respectively." — Roche, John James; The Mathematics of Measurement: A Critical History, The Athlone Press, London, 1998, ISBN 0-485-11473-9, page 184 and Roche, John James; ", B and H, the intensity vectors of magnetism: A new approach to resolving a century-old controversy" American Journal of Physics, vol. 68, no. 5, 2000, doi: 10.1119/1.19459, p. 438; in both cases giving the reference as Egidi, Claudio; editor; Giovanni Giorgi and his Contribution to Electrical Metrology: Proceedings of the meeting held in Turin (Italy) on 21 and 22, September 1988, Politecnico di Torino, Turin (IT), 1990, ISBN 978-8885259003, pp. 53-56
"Séance de clôture". (in French). Paris: Gauthier-Villars. 1901. p. 354. Congrès international d'électricité
^ a b
Gyllenbok, Jan (2018). "line". Encyclopaedia of Historical Metrology, Weights, and Measures, Volume 1. Birkhäuser. p. 141. ISBN 9783319575988 . Retrieved 2018.
^ a b
Klein, Herbert Arthur (1988) . The science of measurement: A historical survey. Dover. p. 481.
Kennelly, Arthur E. "Conference of the Symbols, Units and Nomenclature (S. U. N.) Commission of the International Union of Pure and Applied Physics (I. P. U.), at Paris, in July, 1932, and its Results". Proceedings of the National Academy of Sciences of the United States of America. 19 (1): 146. doi: . 10.1073/pnas.19.1.144 JSTOR 85786.
Kennelly, Arthur E. (1935). "I.E.C. adopts MKS system of units". Electrical Engineering. 54: 1377. doi: 10.1109/EE.1935.6538821.
"Non-SI units accepted for use with the SI, and units based on fundamental constants (contd.)". SI Brochure: The International System of Units (SI) [8th edition, 2006; updated in 2014]. Bureau international des poids et mesures . Retrieved 2018.
International Bureau of Weights and Measures (2006), The International System of Units (SI) (PDF) (8th ed.), ISBN , 92-822-2213-6 archived (PDF) from the original on 2017-08-14 , p. 144