Reading the hand has independent traditions in India, in China and around the Mediterranean, and the European form absorbed material from all of them. Its modern shape owes most to a revival in the nineteenth century, and above all to the practitioner who worked as Cheiro, who systematised the mounts and lines for a large popular readership and also supplied one of the rival letter tables used in numerology.
There is a real science in the neighbourhood and confusing it with palmistry is the standard error. Dermatoglyphics studies the ridge patterns of the fingers and palms, which form in the womb and are fixed for life. Because they develop at a particular stage of gestation, disturbances at that stage leave traces, and certain patterns are genuinely associated with particular chromosomal and developmental conditions. That is a narrow, well-evidenced medical observation.
It is not what palmistry claims. The flexion creases usually read as the life, head and heart lines are folds produced by the hand closing, their length is a matter of anatomy, and no association between them and lifespan, intellect or affection has survived testing. The best documented mechanism for a successful reading is the reading itself: a practitioner holding a client's hand, in conversation, has an unusually rich stream of feedback to work from.
The atlas records the tradition, its long history and its wide distribution, and records that the specific correspondences have not been shown to hold.