This coat-of-arms of physicist
Clerk Maxwell (1831-1879)
corresponds to the ancient [unregistered] arms borne by the
Maxwells of Middlebie, a branch revived by his father shortly after his birth.
Argent a saltire Sable, in chief a mullet Gules, within a bordure Azure.
In Scotland, the right to bear arms is rigorously regulated: The arms at left are the ancient arms of Lord Maxwell, Chief of the Clan Maxwell. The more recent chiefs, including the Earls of Nithsdale, bore more complex arms (the clan has been without a recognised chief ever since William Maxwell of Carruchan died in 1863). The physicist James Clerk Maxwell would not have been allowed to bear the Maxwell shield without some mark of difference, although he was entitled to use the Clan's Strap and Buckle Badge with the Chief's crest (A stag couchant before a holly bush Proper) and motto (Reviresco), and could wear the Maxwell tartan. The arms at right are most probably the unregistered arms which the Maxwells of Middlebie bore before 1672 (when registration with the Lyon Office became compulsory). The branch was revived by James' father, John Clerk Maxwell, who assumed the Maxwell name on inheriting Middlebie (shortly after the birth of his only child).
The Maxwell name had similarly been assumed by John's own grandfather, George Clerk of Penicuik (4th Baronet of Penicuik, son of the Laird of Dumcrieff) who became known as George Clerk Maxwell after he married his first cousin (in 1735) Dorothy, the only child of the heiress Agnes Maxwell of Middlebie, and William Clerk. However, the pattern had been broken in the middle generation, since the son of George Clerk Maxwell who fathered John Clerk Maxwell remained known as James Clerk (his 3 children were thus born Clerk). Because of some obscure rule against holding both estates at Middlebie and Penicuik, James Clerk's estate was divided: Middlebie went to John Clerk Maxwell, whereas his brother George Clerk got the Clerk property at Penicuik. Isabella Clerk, their younger sister, married James Wedderburn and is the ancestor of the Wedderburn-Maxwells of Middlebie who now bear the above arms quartered with Wedderburn's.
James Clerk Maxwell, his father, his mother, and his wife Katherine are buried in the ruins of the old chapel of the village of Parton, Scotland  (the Old Kirk at Parton) where there's now a plaque in his honor, which reads:
His short life was high in distinguished contributions to
every branch of physical science - heat, light, mechanics.
Above all, by unifying the theories of electricity and
magnetism, he established a sure foundation for
modern physics, electrical engineering and atsronomy,
and prepared the way for radio communication and television.
Maxwell died before his 48th birthday, in 1879 (the year Albert Einstein was born).
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