These look like the fonts from the IBM Selectric with the changeable typeballs.

When you needed a greek letter you had to stop there, change typeballs, type the greek letter, then put the regular typeball back on.

On the equations the big stuff would be drawn in by hand from stencils.

On a diagram it could be a mechanical (assisted) drawing that was labeled by typing the same font size, like sketch (a).

When you get to sketch (b) though, this one is a reduced photocopy of the original page that was typed on when labeling the mechanical drawing to begin with.

You can see the way that all of the equations and illustrations could very well be place-held in the text draft until a perfect equation or diagram could then be added later by cutting the proper size horizontal strip of paper containing the original drawing, and "pasting" it over the blank spot in the text where the figure goes. Before photocopying to arrive at the priceless original like this where you couldn't always tell where it was cut-and-pasted.

The Fortran printouts from the IBM line printer look like they could be pasted in both at full-size and photoreduced, on one page at page 20.

But a good typist could avoid that for most equations, they could blaze through the text but when an equation came up it took more time to get one equation right than to type many more pages of text.

As can be seen, it was obviously worth it :)