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One week later, a follow-up. I went through the largest JPG files and was able to shave 7 MB off the final PDF file size, with no noticeable drop in quality, as far as I can tell: https://framagit.org/olivier/thermodynamique/-/commit/063038...

As for the PNG files, I gave up after spending a whole day on them. I was able to compress them losslessly to save 6 MB, but this did not carry over into the PDF, where they are not embedded but re-encoded. The best way to save space here would be to switch to SVG, but this is too much work and last time I tried 12 years ago it did not work well. Alternatively, removing transparency would help (and anyway the source SVG is given for each file). But that’s not very future-proof and somewhere I know there’s a teacher who just is going to right-click-save a diagram and will get a nice crisp transparent-background PNG they can instantly reuse. Verdict: at this point, I am calling it good enough. :-)

Thank you for the compliment! I am touched by the generosity of the HN people today.

It’s accessible with end-of-high school math: you need to be okay-ish with integration and derivation. Practicing engineers might find it a bit slow, but that’s for each to decide :-)

Glad the book can help! Regarding image size, it’s on my todo list now (see thread further down the page).

I am using Payhip for the transaction, and then Paypal. Fees end up averaging 0,5€. Calculating in terms of percentage is not really helpful here at such low prices: there is an incompressible flat rate pretty much anywhere you go. See it differently: these intermediary fees go towards making the UX smooth, the payment secure, reducing fraud etc. I want to spend my energy on the content, not making a credit card form :-)

I used to think that way about the publishing industry too, but I now think that this description is not deserved. Just observing it from an operational perspective: a laptop to type, software to edit, book printers that will talk to you, payment rails, and even access to world-class distribution: it’s all available to us now. On the other side of the market, students and teachers are not locked in either. Barriers to entry are nonexistent. For context, see the links I posted in my other comments on this page. It’s all in our hands!

Thank you! ^^

ha yes :-) Carnot died of cholera aged 36, and Rudolf Diesel committed suicide too. Maybe I should add an appendix about mental health at the end!

The payment for the paid-for PDF is processed through Payhip. As far as I can test here in Germany no cell number is required. Maybe you trigger some extra verification that I don’t?

As for the email, I require it so that I can subscribe all of my readers to a weekly newsl… haha just joking. Juuuuust joking :-) If you try it, you will find that a bogus email address works just fine.

that’s a really good place to start, thank you!

Thank you! To be honest I think there is not much there because when I started 17 years ago my technical skills were much shallower, plotting a diagram to visualize/compare two models would have been quite a lot of work. But if I can be frank, at undergraduate level playing with equations of state is not expected nor a requirement. I’m happy to just say "there are others and they all have some common things". I‘d much rather the students and I spend our energy wrapping our heads around say the concept of entropy and what it allows us to do. Regardless, I appreciate your comment muchly (and shall look up CoolProp tomorrow).

Thanks for that. At first glance, it looks like that is a good place to be, regarding images. I will still investigate when I find time.

I have not kept a very close look on what’s going on. I would say that three things have changed since:

- tablets are everywhere in the classrooms now, so the number of places where a good PDF can do good is much bigger

- there are better workflows to get a high-quality PDF than LaTeX, so much frustration can be saved, and all that can be learned easily with AI tools

- in a sea of AI slop, all the humans are desperate for a One Good Resource they can trust

Go for it!!!!

Following up with actual numbers for the project, from Lulu, in Euros: List Price 43 Print cost 11 Distribution fees (read: Amazon, 50% of selling price): 21.5 Lulu share of profit : 2 Rest to author: 8,5

Because of the different prices on different locales in different currencies the actual share I receive averages 7€ (gross revenue before income tax, although in my case the yearly income is too small to trigger it where I live).

For books sold directly on Lulu List price 43 Print cost 11 Lulu share of profit: 6.5 Rest to author: 25.5

The mindset should not be "this is all that’s left for me", however: a book is many things at once and for better or for worse, Amazon creates a big part of it. Kevin kelly has some excellent advice at https://kk.org/thetechnium/everything-i-know-about-self-publ...

Indeed! Truth be told, I think the book really is missing a chapter on refrigeration systems. I had to call it done at some point for my own sanity. Maybe someone will jump in and add one someday!

Thanks! I think most of the weight comes from the PNG diagrams, but I don’t actually know: I’ll put it on my to-do list to investigate, maybe there are some easy wins here.

Amazon takes the lion’s share, and then the rest of the pie looks very different depending on which route you go. Big publishers print in batches and have very low print/distribution costs. I ended up on the other end of the spectrum, self-publishing with Lulu (print-on-demand, so much higher costs). I wrote an article in French on exploring the economics of textbooks, from the open-source point of view, a few years back: https://framablog.org/2022/01/20/mais-ou-sont-les-livres-uni...

https://ariadacapo.net/