I love those old technical books and their line drawings. Being technical they are often passed by by the 'picture book' buyers so do not always cost an arm and a leg.
I regularly visit book fairs and second hand book shops in the UK and hunt down such tomes. Last years find was one from the ICS Reference Library on tramway Systems, tracks, overhead works, cars and equipment, brakes, motors and controllers, DC Railways, AC Railways, Electric Signalling.
£25. I do not think it very rare as I have seen on sale since at other book fairs.
By the way ICS or International Correspondence School still exists, but tramway course are no longer offered!