Firstly understand the difference between legibility and readability - the best short text on this - IMHO - is the section in Walter Tracy’s ‘Letters of Credit’. Some of the confusion over these topics by those who should have known better, can be better understood now as a result of the research of William Berkson & Peter Enneson in ‘Readability: discovery and disputation’ - the retrieval of the reputation and research of Matthew Luckiesh (1883-1967) - in Typography Papers · 9.

Edward Tufte’s classic ‘The Visual Display of Quantitative Information’ is a highly refined introduction to and exemplar of the presentation of non-text information and an appeal to eliminate unnecessary visual ‘noise’.

Balance and selection are rarely given enough emphasis - images can easily overwhelm and undermine text, especially if they have their own extensive captions - the main text matter in many highly illustrated books are seldom ever read properly & people who have browsed the images will swear that they’ve read the book! Keep to the text grid unless you are prepared to abandon it for a dramatically different page structure (eg. full bleed) in an inset.

Tschichold’s ‘On the Correlation of Text to Page Area’ is the seminal text not only to understand the historic role of the grid, but demonstrates the common heritage and geometric logic of the ergonomics and perceptual balance of the double page spread both in its classic form but also as a congruent basis of asymetric layout on a page proportioned grid. Tschichold’s classic book grid also generates a 9x9 proportional modernist page grid matrix - see below for construction - the crucial element is the resulting rectangle top left of the recto text area - an exact 1/9 x 1/9 page proportion grid unit. And it works for any page proportions giving you margins, text area and layout. Key to the scriptorum!

Preserving sizes & stroke widths from the main text is a good aim, but a switch to a sans typeface with the flexibility of for example Univers for diagrams and labelling is a well established tradition. If you switch fonts in bodies of text - take the trouble to exactly match x-heights - something that almost cannot be done in letterpress but is almost trivial with digital fonts.

The Monotype Recorder on ‘The Setting of Mathematics’ by Arthur Phillips (1956) is a one of a kind reference, if you should ever need it. Some of the University Presses and their typographers have recognisable House Styles and Rules for dealing with tabular material and it’s worth collecting your own annotated examples - I’m a great believer in design by exception - follow good models as carefully as you can - correcting clear errors and only inventing new treatments when confronted with genuinely new materials not previously incorporated in the series style.

See the ‘Book Design: Text Format Models’ by Stanley Rice (Dec 1978) when designing your style architecture.

You’re asking good questions - borrow from past giants but always imagine personas for your readers and the circumstances of their reading - go deep and enjoy.

The treatment of captions is critical, as it provides a working bridge. between body text and images, that informs page layout.

A lot depends on how much information, and in how many categories, is contained in the captions.

Bear in mind that many, if not most people, barely glance at pictures before reading captions.

IMO, nothing is more annoying in a book than captions which are not right beside the images to which they refer, or not organized in a way that is consistent.

I would suggest bookstore/library perusing of books similar in content to yours, identifying those with caption design which communicates promptly and efficiently to you, analyzing why, and adopting a similar strategy.

Thank you, this all makes sense :)

With respect to images without captions but which are referred to by the text, I wonder about their placement on the page or spread. It seems to help when the images’ dimensions align with, say, a 9x9 grid layout of the page but I am reluctant to flow text around images. I have always somehow disliked how this scatters text.

There are some hints in Designing Books which helps.

Tim: Thank you so much for all the tips, I found a few excerpts from The Form of the Book. The other references I've added to my list :)

Nick: That's a good idea, I'll spend a day at the local library and poke around :)

I know this was a long time ago - but I just wanted to endorse Nick’s suggestion of going to look for good models - I am a huge advocate of design by exception - find a really good model for similar material and use its elements that work best - spend your precious creative time crafting the elements that are uniquely required by your new content that aren’t already provide in your model ... check out the bible - Stanley Rice - Book Design: Text Format Models from the early pioneer days of style-sheets - I’ve suggested before that someone could make a killing and/or earn a PhD by doing a modern digital equivalent - just say you heard it here first ...