The calendar of correspondence, titled "minute of letters" by its creator William Sommerville, consists of letter abstracts in seven sections.

1. "minute of letters received"; march 9 to december 28, 1811; pages 4-28
2. "minute of letters wrote"; february 3 to december 14, 1811; pages 1-24
3. "minute of letters wrote"; january 10 to december 29, 1810; pages 1-16
4. "minute of letters wrote"; january 5 to february 2, 1811; pages 1-3
5. "minute of letters received"; january 3 to september 19, 1810; pages 1-12
6. "minute of letters [received]"; september 29 to december 29, 1810; pages 13-18
7. "minute of letters received"; january 12-26, 1811; page 19

Correspondents and persons recorded in the calendar of correspondence include:
men in public office on the national and local levels,
local residents,
members of the Sommerville family,
Revolutionary War veterans,
newspaper editors,
and Post Office clients and officials.
See the name index in box 3 for an alphabetical listing.

Subjects of the correspondence include:
estates,
lottery - Susquehanna Canal,
lottery - Union College,
lottery - Wilmington College,
lottery - smallpox vaccine institute,
politics,
deaths,
mail schedules,
business affairs,
elections,
apprentice,
and vaccine legislation.

The diary of William Sommerville is in three parts, each representing a calendar year.

1. january 1 to december 24, 1810; pages 1-209
missing pages: 23-30, 55-76, 83-84, (page 84 occurs twice, numbered second time), 92-93, 96-97, (page 107 occurs twice), 110-115, 120-125, 127-130, 140-143, 158-161, 164-173, 180-187, 190-200, 207-208)

2. january 1 to december 31, 1811; pages 1-205
missing pages: 7-8, 11-14, 31-36, 47-48, 51-54, 61-62, 67-68, (page 70 not numbered), 108-119, 124-129, 136-137, 142-143, 160-161, 164-173, 180-181, 190-199, 202-203

3. january 1 to december 26, 1812; pages 1-195
missing pages: 34-39, 58-59, 74-79, 88-89, 133-134, 140-145, 154-155, 164-167, 176-179

People mentioned or commented on in the Diary include:
persons in politics and government on the national and local levels;
local residents;
members of the Sommerville family;
post office clients and officials;
military personnel;
Revolutionary War veterans;
New York, Baltimore, and local newspaper editors;
local doctors and doctors associated with the smallpox Vaccine Institution;
ministers of various church denominations;
and government officials in France and England.

Subjects mentioned or commented on in the Diary include:
post office business;
family affairs;
births;
marriages;
deaths;
apprentice[s];
slaves;
agricultural products;
methods, prices, and labor;
elections;
general store;
weather (daily);
Martinsburg and its residents (frequently);
mills;
taverns;
european affairs;
patriotism and Americanism;
churches;
schools;
reminiscences about the Revolutionary War;
opinions on ministers and religion;
lotteries -- Vaccine;
lotteries -- Delaware;
lotteries -- Susquehanna Canal;
lotteries -- Washington Monument;
lotteries -- Union College;
lotteries -- Wilmington College;
travel;
militia muster and draft;
War of 1812 -- cause;
War of 1812 -- local and national reaction;
War of 1812 -- battles;
and government policy.

Includes letter (1799) from Sarah Brown to William Sommerville;
and letters (1832-1888) between William Sommerville's daughter Elizabeth Sommerville (Edwards) and William B. Edwards, including their daughter and others. William B. Edwards was a Methodist circuit rider.

Subjects include personal and family affairs, churches and the ministry, Martinsburg, and slavery, among other topics.