{{Infobox Scientist
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|birth_date        =  September 6, 1811
|birth_place       = Georgetown, Washington, D.C.
|death_date        = February 9 1865
|death_place       =  Washington, D.C.
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|ethnicity         = 
|field             = astronomy
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|known_for         = United States Naval Observatory
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}}'''James Melville Gilliss''' (born September 6, 1811 in Georgetown, Washington, D.C. - died February 9 1865 in Washington, D.C.) was an astronomer, United States Navy officer and founder of the United States Naval Observatory.

==History==
Gilliss joined the Navy in 1827 as a Delaware'', the ''Java'' and the ''Concord''.

In 1831 he started his studies at the University of Virginia, and went to Paris for further studies one year later. He got the position of an assistant at the Depot of Charts and Instruments in Washington in 1836. He was also responsible for astronomical observations.

He made an astronomical research journey under Captain Charles Wilkes in 1837. He made observations on the differences of longitude by means of moon-culminations, made metrological observations and worked on new instruments.

Gilliss was made a lieutenant in 1838.

In August 1842, the U.S. Congress passed a bill authorizing the creation of an observatory, intended to be a "National Observatory" by John Quincy Adams who was an amateur astronomer it came to be under the command of the navy and thus for 12 years it was alternately called the National Observatory and the U.S. Naval_Observatory although the latter was used less until a bill was passed clarifying what it would be officially called. Until that point every item, every document and letter had to be duplicated because of the two names of "National Observatory" and "Navy Observatory.". This was but another time consuming duty that came to  Matthew Fontaine Maury who headed the observatory from its beginning until 1861. Another of the many duties of superintendent M. F. Maury during this time period was to oversee all publications that embraced every maritime survey.

'''James Melville Gilliss''' (* Georgetown, Washington (D.C.), USA; &dagger; 9. Februar 1865 in Washington (D.C.)) war ein US-amerikanischer Astronom und Marineoffizier.
 
Gillis trat der US-Marine 1827 15-jährig bei, er hatte den Mannschaftsdienstgrad eines midshipman. Er diente auf der „Delaware“, der „Java“ und der „Concord“.

1831 erhielt er die Möglichkeit zu einer höheren Ausbildung durch die Marine und studierte zunächst ein Jahr an der University of Virginia und setzte seine Studien anschließend in Paris fort. 1837 wurde er als Assistent in das Marinedepot für Anzeigen und Instrumente versetzt. Er war dort auch für astronomische Beobachtungen verantwortlich.

Er unternahm eine astronomische Forschungsreise unter Captain Charles Wilkes, erarbeitete Korrekturen für die Längengradbestimmung, Mondbahn, erfand neue Beobachtungsinstrumente und untersuchte meteorologische Phänomene. 1838 wurde er zum Leutnant befördert.

Gilliss begründete 1841 im Rahmen seiner Tätigkeit das Captains leitete, als erstes nationales Forschungsobservatourium der USA. Dort unternahm er 1848 bis 1851 Bestimmungen zur Sonnenparallaxe vor. Er publizierte zahlreiche seiner Beobachtungen.