Thank you so much for this! I was just searching for a 1910's brassiere pattern last night! :)
FYI, I made a bra from your pattern and it worked well for me. Although I am a larger size than you (34DD) I neglected to check the measurements before I cut it out. Fortunately I used a wide seam allowance. I let out the side seams about 5/8" on each side. The princess seams were let out over the apex and taken in at the upper bust. The original dart placement worked for me--I just made them about 1/4" longer. The fabric was a stiff cotton ticking (that wrinkles like all get out). I didn't use lace--just made it plain because I was concerned that it would compromise the support. I had planned to bone it, but I have enough support without the boning. I used hook and eye tape for the closure.The bra is really comfortable, and I'm thinking about taking it for a spin under contemporary clothes. Now I need to make a prettier version.
I'm so glad the pattern came in handy for you!!! Thank you so much for telling me all about it. Made my day. :D