Which Ross?

Sir John Ross, RN (1777-1856)
British rear admiral, Arctic explorer

OR

Sir James Clark Ross, RN (1800-1862)
British naval officer, Arctic and Antarctic explorer
(the Ross sea and Ross Ice Shelf, in Antarctica, are named after him)

The above drawing is from
Heraldry:  A Pictorial Archive for Artists & Designers
(Arthur Charles Fox-Davies)
[ Thanks to  Guy H. Power  for unearthing this one... ]

The lengthy blazon given below is quoted in James Parker's
Glossary of Terms Used in Heraldry  (under "sphere")
where it's attributed to "Sir John ROSS, C.B., Capt. R.N.", the Arctic
explorer who was the  uncle  and mentor of James Clark Ross.
James Clark Ross discovered the North Magnetic Pole
on June 1st, 1831, during an expedition led by his uncle.
So, who made the heraldic claim to the discovery?

Gules, three estoiles in chevron between as many lions rampant Argent;
[for augmentation] a chief Or, thereon a portion of the terrestrial globe Proper,
the true meridian described thereon by a line passing from north to south Sable,
with the arctic circle Azure; within which the place of the magnetic pole
in latitude 70°5'17'', and longitude 96°46'45'', west, designated by
an inescutcheon Gules, charged with a lion passant gardant of the First;
the magnetic meridian shewn by line of the Fourth passing through
the inescutcheon with a correspondent circle, also Gules,
to denote more particularly the said place of the magnetic pole;
the words following inscribed on the chief, viz., "Arctæos Numine Fines".

Crest:   Two helms.
Dexter:  Over a downward pointing floating compass [?]
the Union Jack inscribed  "1st June 1831"  fesswise.
Sinister:  A fox's head erased proper [for "Ross"].

Motto:   Spes Aspera Levat  (hope lightens difficulties).