\cite{Lahti2015}The general trend in the catalogues that we have studied is that octavo format supersedes other printing formats during the eighteenth century. [FOOTNOTE: Henrik Horstbøll has previously studied the relevance of octavo format for Danish publishing in detail based on analogue methods and smaller samples. Our work confirms his findings and further extends the scope by studying a much larger and cross-European data. See, Henrik Horstbøll. Menigmands medie. Det folkelige bogtryck i Danmark 1500–1840. Copenhagen: Det Kongelige bibliotek & Museum Tuscalanums Forlag, 1999; Horstbøll. ‘In octavo. Formater, form og indhold på det populære litterære marked i 1700-tallets Danmark’. In Bokens materialitet. Bokhistoria och bibliografi, ed. Mats Malm, Barbro Ståhle Sjönell and Petra Söderlund. Stockholm: Svenska vitterhetssamfundet, 2009 and Horstbøll. ‘Bibliografi som boghistorie’, Biblis (2010:50), 90–95]. We can measure this by looking at a simple title count of documents published in different formats, or we can study the paper consumption of these formats in which case we are focused on the print area of the documents instead of counting the number of documents. We find the study of the print area quite useful and our choice in this article has been to examine particularly the paper consumed in the printed documents also so that we can compare our findings to our earlier studies that also focus on paper consumption. When we examine the publishing trends of book formats in the HPBD, we notice that at a general European level the rise of octavo format is particularly strong during the eighteenth century (fig.???). This is confirmed by ESTC (fig.???) and SNB (fig.???) where Octavo is not only the fastest gainer of the market, but also holds the largest share by the end of the eighteenth century. If we look at particular places with respect to octavo share in HPBD, a striking feature is the octavo share in German cities of Frankfurt (fig.???), Leipzig (fig.???), Halle (fig.???) and Berlin (fig.???). The manner in which folio drops and octavo rises in German soil during the eighteenth century suggests that octavo format was the high rising star of the Enlightenment. 
Among this type of general Europe-wide trends, there are of course local differences, and for example in Turku (fig.???) (and Finland that was part of Sweden at the time) the rise of octavo comes much later than in Sweden in general. This was due to the fact that the main part of the documents printed in Finland were official documents,  pamphlets and theses. If we look at the fractions of formats in Turku, another way of saying this would be that printing in Turku only takes off in the later eighteenth century whereas in Stockholm hand press printing industry seems to have reached a different level of maturity earlier (fig. ??). The simplest explanation for the success of octavo format is that it was particularly suited for smaller books that could be carried around and read practically anywhere, whereas quarto (and folio) formats were more commonly used in governmental and academic documents; pamphlets and in larger books alike, especially in the earlier centuries [FOOTNOTE: about relationship between books and pamphlets, see Joad Raymond, Pamphlets and pamphleteering in early modern Britain, Cambridge University Press, 2003) **]. We have analysed the relevance of the rise of octavo with respect to book printing in the case of "history" publishing earlier [CITE: DOI: http://doi.org/10.18352/lq.10112) **]. Of course, larger formats in book printing carried certain prestige also in the eighteenth century even when reading started to be partly removed from stately mansion libraries, becoming more equal and the price of the book turned out to be a decisive factor for dissemination of ideas [CITE: Allan, D. W. (2013). Politeness and the Politics of Culture: An Intellectual History of The Eighteenth-Century Subscription Library. Library History29, 159-169.  Allan, D. W. (2008). A Nation of Readers: The Lending Library in Georgian England. London: The British Library. Allan, D. W. (2008). Making British Culture: English Readers and the Scottish Enlightenment, 1740-1830. Routledge. Towsey, Mark (2010). Reading the Scottish Enlightenment: Books and their Readers in Provincial Scotland 1750-1820. Leiden and Boston: Brill. **] When considering quarto and octavo publications, it is quite telling that David Hume (1711-1776) wanted his History of England to be printed in quarto sized fine-paper six-volume set in late 1760s (as it had appeared earlier), but the editions that were actually published after 1767 until Hume's death (including the 1778 posthumous edition) are octavo editions in eight volumes.  Octavo editions might have lacked the exclusivity and finesse of heavier tomes with large margins that connoisseurs might have preferred for aesthetic reasons, but it was particularly the cheaper and smaller formats, octavo and duodecimo, that changed the nature and relevance of printing in the later part of the eighteenth century.