In 1872, a sequel - Through the Looking-Glass - was published. Its somewhat darker mood possibly reflects the changes in Dodgson's life. His father had recently died (1868), plunging him into a depression that would last some years.
The Hunting of the Snark
In 1876, Dodgson produced his last great work, The Hunting of the Snark, a fantastic "nonsense" poem, exploring the adventures of a bizarre crew of variously inadequate beings, and one beaver, who set off to find the eponymous creature. The painter Dante Gabriel Rossetti reputedly became convinced the poem was about him.
Photo of Alice Liddell taken by Lewis Carroll (1858).
In 1856, Dodgson took up the new art form of photography, first under the influence of his uncle Skeffington Lutwidge, and later his Oxford friend Reginald Southey.
He soon excelled at the art and became a well-known gentleman-photographer, and he seems even to have toyed with the idea of making a living out of it in his very early years .
A recent study by Roger Taylor and Edward Wakeling exhaustively lists every surviving print, and Taylorcalculates that just over fifty percent of his surviving work depicts young girls. He would later use many of his photographs of children in conjunction with his writings to add illustration to his work. Alexandra Kitchin, known as "Xie" (pronounced "Ecksy"), was his favourite photographic subject. From 1869 until he gave up photography in 1880, Dodgson photographed her at least fifty times, ending just before her sixteenth birthday. Less than a third of his original portfolio has survived, however; Dodgson also made many studies of men, women, male children and landscapes; his subjects also include skeletons, dolls, dogs, statues and paintings, trees, scholars, scientists, old men and little girls. His studies of nude children were long presumed lost, but six have since surfaced, four of which have been published.
Photo of John Everett Millais and his wife Effie Gray with two of their children, signed by Effie (c. 1860)
He also found photography to be a useful entr?e into higher social circles. During the most productive part of his career, he made portraits of notable sitters such as John Everett Millais, Ellen Terry, Dante Gabriel Rossetti, Julia Margaret Cameron, Michael Faraday and Alfred, Lord Tennyson.
Dodgson abruptly ceased to photograph in 1880. Over 24 years, he had completely mastered the medium, set up his own studio on the roof of Tom Quad, and created around 3,000 images. Fewer than 1,000 have survived time and deliberate destruction. His reasons for abandoning photography remain uncertain.
With the advent of Modernism tastes changed, and his photography was forgotten from around 1920 until the 1960s. He is now considered by many to be one of the very best Victorian photographers, and is certainly the one who has had the most influence on modern art photographers.
To promote letter writing, Dodgson invented The Wonderland Postage-Stamp Case in 1889. This was a cloth-backed folder with twelve slots, two marked for inserting the then most commonly used 1d. stamp, and one each for the other current denominations to 1s. The folder was then put into a slip case decorated with a picture of Alice on the front and the Cheshire Cat on the back. All could be conveniently carried in a pocket or purse. When issued it also included a copy of Carroll's pamphletted lecture, Eight or Nine Wise Words About Letter-Writing.
Another invention is a writing tablet called the Nyctograph for use at night that allowed for note-taking in the dark; thus eliminating the trouble of getting out of bed and striking a light when one wakes with an idea. The device consisted of a gridded card with sixteen squares and system of symbols representing an alphabet of Dodgson's design.
Among the games he devised outside of logic, croquet, billiards and those played on a chess board, there are a number of word games, including an early version of what today is known as Scrabble. He also appears to have invented, or at least certainly popularised, the Word Ladder (or "doublet" as it was known at first); a form of brain-teaser that is still popular today: the game of changing one word into another by altering one letter at a time, each successive change always resulting in a genuine word. For instance, CAT is transformed into DOG by the following steps: CAT, COT, DOT, DOG 
Other items include a rule for finding the day of the week for any date; a means for justifying right margins on a typewriter; a steering device for a velociam (a type of tricycle); new systems of parliamentary representation; more nearly fair elimination rules for tennis tournaments; a new sort of postal money order; rules for reckoning postage; rules for a win in betting; rules for dividing a number by various divisors; a cardboard scale for the college common room he worked in later in life, which held, next to a glass, insured the right amount of liqueur for the price paid; a double sided adhesive strip for things like the fastening of envelopes or mounting things in books; a device for helping a bedridden invalid to read from a book placed sideways; and at least two ciphers. .
Richard Grey's Memoria Technica and John Jaques In Statu Quo traveling chess set have at times been mistakenly credited to Dodgson.
The later years
Over the remaining twenty years of his life, throughout his growing wealth and fame, his existence remained little changed. He continued to teach at Christ Church until 1881, and remained in residence there until his death. His last novel, the two-volume Sylvie and Bruno, was published in 1889 and 1893 respectively. Its extraordinary convolutions and apparent confusion baffled most readers and it achieved little success. It does contain an extremely concise account of three-valued logic when Bruno counts "about a thousand and four" pigs because he is certain about the four but estimates the remainder. In three-valued logic, unknown plus four = unknown (see Null (SQL)).
He died on January 14, 1898 at his sisters' home, 'The Chestnuts' in Guildford, of pneumonia following influenza. He was 2 weeks