RE: 149b dial plate listed above by Paul-f on "Western Electric Dial Plates". One reply mentioned having the 149b as shown above. I have that also right in front of me. However, a web site I saw last night shows that same one as a 132b notched. That site said the 132b could be notchless or notched. Mention is made of the 132 has having the 3 prongs on back of course. The 149b II36 dial plate I just looked at on a B1/202/AB does not have the three prongs.
So, are the the three prongs on the back a major difference between a 132 and 149 plate? Mention was made of "catalog error" in the 149 diagrams. Perhaps the transition period was not as sharp as imagined, perhaps a late 132 did resemble an early 149. The "132" I seem to have is like the other corresponder's, no numbers on back(or on front). Thanks.
I also believe that to be an error in the catalog. The 149 type plates closes the large open center area around the shaft to just enough for the shaft to emerge.
The number plates on the No.4 dials on the early D1 handset mountings for 102 and 202 instruments had a large diameter opening with a notch, the "notched 132", ca. 1930-1934.
I believe the first plate that closed the center area was the all-cellulose acetate pate developed by ca. 1931, and having patent dates of 1934 by Cox and Gutberlet of Philadelphia. Their review of prior art mentions the short-coming of the previous design with the wide opening. The C&G plate was apparently tested in the Bell System in various places with dates between Q2-33 and Q4-34. I believe I own the earliest one found to date (II-33). These are extremely rare items.
The 149 plate appears ca. 1934. It may well have copied the closed design from Cox et al. It is inconceivable that the 149B plate would still have the opening in 1935.
