The correct spelling of our subject's given name is Aquila.  It's a Latin word meaning "eagle," and it's found as a given name in the New Testament.  It's pronounced AK-wi-luh, not a-KWIL-luh. 

The children's birthyears given in secondary sources appear to be guesses.  Thomas's birthyear is given as 1796 or 1799, the latter of which may be correct because it agrees with the 1850 census.  But if Thomas's age in the 1860 census is the correct one, then Aquila had a wife prior to Mary OSBORN, which is reasonable given Aquila's age.

Most of the birthyears given in secondary sources appear to be guesses.  Sylvester is said to be born in 1811, but the 1820 and 1830 censuses show no son born after 1810.  Mildred is said to be born 1832 — when Anne would have been 53 years of age — which is biologically out of the question; based on the 1850 census, where Mildred is age 28, it's clear that "1832" must be someone's typo for 1822, blindly copied and repeated by many secondary sources.  Please, if you aren't going to dig out the primary sources, at least check your data to see if it makes sense, because a woman having a baby at age 53 does not make sense.

1.  Jordan R. Dodd, ed.  1993.  Kentucky Marriages:  Early to 1850.  Liahona Research, Orem, UT (Broderbund CD-229):

Blandford, Aquilla	Osborn, Mary	5 Mar 1796	Nelson Co.
Blandford, Aquilla	Carrico, Anne	14 Feb 1804	Washington Co.

2.  Anon.  1991.  The 1795 Census of Kentucky [as constructed from tax lists].  T.L.C. Genealogy, Miami Beach, FL (said to include every extant tax list from every county existing in the state of Kentucky in 1795):

Pg	Name	County
16	Blandford, A James	Nelson
	Blandford, William	Nelson

Our subject not found, unless he is the James A. BLANDFORD in Nelson Co., KY (names were meant to read from right to left, i.e., James A. Blandford, not A. James Blandford).  Some secondary sources do call our subject, "James Aquilla" or "Aquilla James," so it may, indeed, be him (males were taxed beginning at age 16, whether married or not).  William is presumably Aquila's father.

3.  Census Index:  U.S. Selected Counties, 1800 (Broderbund CD-312):  the 1800 Kentucky census was lost, but where available, tax lists are substituted on the CD.-

1800 Tax List

Blandford, Aquilla

KY

Washington Co.

4.  1810 Census Index/Images (online at Ancestry.com; Image #6 of 9 — list was roughly alphabetized; extracted by Diana Gale Matthiesen):¤•

1810

KY

Washington Co.

Springfield

Roll M252_8

p. 3/347/850

Ln. 11

Aquila Blandford

32010-20010-01

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
3 males	9 or under	1800-1810	= Sylvester (b. 1810?) = Joseph (b. 1805) = Martin (b. 1800?)
2 males	10-15	1794-1800	= Thomas (b. 1798/9) = William (b. 1798?)
1 male	26-44	1765-1784	= Aquila (b. 1765-70)
2 females	9 or under	1800-1810	= Mary (b. 1809) = Teresa (b. 1807?)
1 female	26-44	1765-1784	= Anne (b. 1778/9)
1 slave	all ages	in or bef. 1810	= ?

5.  1820 Census Index/Images (online at Ancestry.com; Image #14 of 17 — mis-indexed "Agmler"; also mis-indexed as being in the Town of Lebanon, please see this post at GenForum.com for problems with the online images of these pages; extracted by Diana Gale Matthiesen):¤•

1820

KY

Washington Co.

Roll M33_29

p. 51

Ln. 13

Aquiler Blanford

020301-52010-0-600

0200-0010

These data indicate:

No., Race, Gender	Age Class	Therefore Born	Individuals Inferred
2 white males	10-15	1804-1810	= Sylvester (b. 1810?) = Joseph (b. 1805)
3 white males	19-25*	1794-1801	= Martin (b. 1800?) = Thomas (b. 1798/9) = William (b. 1798?)
1 white male	45 or over	in or bef. 1775	= Aquila
5 white females	9 or under	1810-1820	= Ann (b. 1820?) = Matilda (b. 1816) = Elizabeth (b. 1814) = Susan (b. 1813) = Daughter A
2 white females	10-15	1804-1810	= Mary (b. 1809) = Teresa (b. 1807?)
1 white female	26-44	1775-1794	= Anne (b. 1779)
6	people engaged in agriculture
2 male slaves	14-25	1794-1806	= ? ?
1 female slave	26-44	1775-1794	= ?
*In the 1820 Census, the third column is age class 16-18 and the fourth column is age class 16-25; therefore, any individual in column three is duplicated in column four.  By subtracting the number in column three from the number in column four, you can create an age class "19-25."

6.  1830 Census Index/Images (online at Ancestry.com; Image #23-24 of 116 — indexed "Aquilla"; extracted by Diana Gale Matthiesen):¤•

1830

KY

Washington Co.

Roll M19_42

p. 162

Ln. 22

Aquillar Blandford

000 042 001 - 012 311 010

011000-002000

These data indicate:

No., Race, Gender	Age Class	Therefore Born	Individuals Inferred
4 white males	20-29	1800-1810	= Sylvester (b. 1810?) = Joseph (b. 1805) = Martin (b. 1800?) = ?
2 white males	30-39	1790-1800	= Thomas (b. 1798/9) = William? (b. 1798?)
1 white male	60-69	1760-1770	= Aquila
1 white female	5-9	1820-1825	= Mildred (b. 1822?)
2 white females	10-14	1815-1820	= Ann (b. 1820?) = Matilda (b. 1816)
3 white females	15-19	1810-1815	= Elizabeth (b. 1814) = Susan (b. 1813) = Daughter A
1 white female	20-29	1800-1810	= Mary (b. 1809) or Teresa (b. 1807?)
1 white female	30-39	1790-1800	= daughter-in-law?
1 white female	50-59	1770-1780	= Anne (b. 1779)
1 male slave	10-23	1806-1820	= ?
1 male slave	24-35	1794-1806	= ?
2 female slaves	24-35	1794-1806	= ? ?

Our subjects only had five sons in the 1820 census, so could not have six here.  Thomas was not married 'til November of 1830 and Joseph was not married 'til 1833, so we would expect them to still be in the household.  There must be others in the household who are not children of our subjects.  Listed between Edward OZBORNE and John S. CARRICOE.

7.  1840 Census Index/Images (online at Ancestry.com, Image #73-75 of 94; extracted by Diana Gale Matthiesen):¤•

1840

KY

Washington Co.

Roll M704_125

pp. 131B-132A

Ln. 6

Ann Blanford

000 010 - 000 031 200

002000-003000

0300000

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
1 white male	20-29	1810-1820	= Sylvester? (b. 1810)
3 white females	20-29	1810-1820	= Mildred? (b. 1821/2) = Matilda (b. 1816) = Elizabeth (b. 1814)
1 white female	30-39	1800-1810	= Mary (b. 1807-9)
2 white females	40-49	1790-1800	= ?
0 white females	50-69	1770-1870	= Anne (b. 1779)
2 male slaves	24-35	1804-1816	= ? ?
3 female slaves	24-35	1804-1816	= ? ? ?
3	persons employed in agriculture

Either the enumerator erred badly or Anne was fibbing about her age big time.  Listed next to Edward OSBURN.

8.  1850 Census Index/Images (online at Ancestry.com; Image #202 of 208):  Washington Co., KY, Roll M432_221, p. 231B, 1402/1402, enumerated 12 Nov 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):¤•

Ann Blanford	71	F			2100	Md
Mary Blanford	42	F				Ky
Elizabeth Blanford	33	F				"
Mildred Blanford	28	F				"
James Carrico	19	M				"

Listed next to Edward OSBOURN.

9.  Broderbund.  World Family Trees.  Vol. 4, Pedigree #3517.

10.  WorldConnect / Ancestry World Trees (online at RootsWeb.com/Ancestry.com).

11.  LDS.  Family Search: Internet Genealogy Service: Pedigree Resource File (index to CDs, online at FamilySearch.org).