Mary Black wrote her Key to Weaving back in the 1940s and updated it regularly through her life. As such it reflects the style and attitudes of the day. The photos are black and white (although later updates did include some colour plates) and diagrams are hand drawn because that is how information was processed at that time. And sometimes a hand drawn illustration is more informative than a photo anyway because it cuts away anything that isn't essential to conveying the point.
Many people now look at (New) Key to Weaving with a jaundiced eye. We have grown so accustomed to pretty pictures and lots of white space on the page where Black's book is text dense. The language also reflects the time and seems very formal and stilted to some people which they find off putting.
But for those people who can process this kind of approach, the book holds a wealth of information.
This is most definitely a book where you need to read the introductory bits. Black attempts to convey a lot of information in a small amount of space, so understanding what she is doing will help in figuring out what is necessary.
For example, in the middle photo, Black provides the tie up for both rising and sinking shed looms. First you have to know which type your loom is (and I'll discuss that in another post at some point) but even if you don't know, choose one. As mentioned yesterday, if you guess wrong you will still get a result, it will just be 'upside down'.
As Black guides you through the information, the technical information gets a bit more 'complex', as in the bottom photo which shows a unit weave which will create blocks which can then be fitted together to make motifs.
A profile draft takes up much less paper to convey, so she has given the profile draft, then how the treadles will be tied up, then also written out the treadling as a profile. You need to understand how the weave structure works, then you can just plug in the appropriate sequence. But all of this is not shown thread by thread - you have to have read the introductory bits so that you have the key in order to obtain the results.
Weaving is a lot like coding. You have to understand what the code is and be able to translate it into meaning.
Weaving software makes doing this kind of translation easy but it isn't 100%. For example, in Fiberworks, I prefer to have the Bronson Lace weft floats be my 'right' side and the software does the warp floats as the 'right' side as its default. After I enter my blocks, then select Bronson Lace, I then edit the tie up so that I have the weft floats on the top of the cloth as I weave it.
I prefer the straight progression of twill to descend from the back shaft to the front shaft when possible, so I will use the shaft shuffler tool to do that if I am converting a profile draft into, for example, twill blocks. (I do this because I find it more ergonomic/efficient to thread from the back most shaft to the front most.)
Weaving drafts are not set in stone. As long as the cloth looks the way you want it to, a draft can be edited to meet your requirements. Especially the treadling. If the author places the plain weave treadles to one side and your preference is to have one on each side? Change it to reflect what you prefer.
Mostly I like my plain weave treadles to either side, but for some weave structures, they might go both on one side (Bronson Lace), or even in the middle (Huck Lace). Because to place them that way makes the treadling progression make more sense to me and I make fewer mistakes.
My copy of New Key to Weaving was purchased in 1975 when I enrolled in the weaving class at the college. It, along with Davison and Shirley Held's Weaving were my textbooks. Three very different volumes, still treasured volumes in my library.