Wikipedia defines a chapbook as “an early type of popular literature printed in early modern Europe. Produced cheaply, chapbooks were commonly small, paper-covered booklets, usually printed on a single sheet folded into books of 8, 12, 16 and 24 pages. They were often illustrated with crude woodcuts, which sometimes bore no relation to the text. When illustrations were included in chapbooks, they were considered popular prints.
“The tradition of chapbooks arose in the 16th century, as soon as printed books became affordable, and rose to its height during the 17th and 18th centuries. Many different kinds of ephemera and popular or folk literature were published as chapbooks, such as almanacs, children’s literature, folk tales, nursery rhymes, pamphlets, poetry, and political and religious tracts.”
The chapbooks available in the National Library of Scotland’s online Digital Gallery were printed in the 18th and 19th centuries across the country. Many chapbook printers were active in the Central Belt and Aberdeen. But chapbooks were also printed in other towns, for instance in Inverness, Brechin, Fintray, Banff, Tain and Kilmarnock.
Chapbooks formed the staple reading material of the common people. They deal with every topic under the sun. You can read about trials, transvestites, war; religion, free masons, crime; courtship, Jacobites, the Irish; street life, sports, slavery; prostitution, politics, pirates; emigration, diseases, Scottish life and many more things.
Seven chapbooks were published in Inveraray, and they are in written in Gaelic. They mostly contain songs. Chapbooks were also written for children, not just for adults.
Your Scottish ancestors probably read some of these chapbooks. You can find out more about the Library’s most important collection of chapbooks, at the National Library of Scotland’s web site at http://blog.nls.uk/scottish-chapbooks-now-online and in the Lauriston Castle Collection at http://goo.gl/IWWPSj.