Contributed by John Novack.

From Bell Telephone Magazine, Spring 1948. Contributed by Steve Cichorsky.

Contributed by John Novack.

171 pages.? Provides a reference to common terms used in the 021 series of courses.? Marked for internal use within the Bell System.

Topics include: CO Equipment, Apparatus, Equipment, Cable & Wiring, Engineering Aids, References (e.g. Standards, Technical Design Manual, BSPs), and Ordering Apparatus.

Version 2023-06-25. This chart documents the history of Western Electric dial generations of the lineage started by Oscar Forsberg in 1915. It traces the history of apparatus codes through generations No. 1 to 6.  The apparatus codes also trace the application area of each dial type.
This is a work in progress, a snapshot, and will be updated as new information and documentation continues to emerge.

Created and contributed by Karl Brose.

This document is covered by Creative Commons Attribution-ShareAlike 4.0 International Public License. For details, click on the link in the lower right corner of the pdf.

Note: Prints best on 11x17" paper. Printing on 8.5x11" paper results in very small font size.
Most Windows print drivers allow "poster" printing on multiple 8.5x11" pages. For example, to print on two pages, which may be taped together:
    Select: Print / Paper Size & Handling / Poster / Tile Scale: 125% / Landscape

Special issue. Interesting early perspective on the adoption of Machine Switching in the Bell System. Contributed by the Connections Museum. Processing by Remco Enthoven and Paul Fassbender.

April 1920. Chicago Telephone Company. Feature article on Machine Switching in the Bell System.  Contributed by Steve Cichorsky. OCR by Clint Gilliland.

Extract showing the WE 392 ringer and gong shapes.  Contributed by Steve Cichorsky.

February 1924.  Machine dialing demonstrations and equipment.  Contributed by Steve Cichorsky.  OCR by Clint Gilliland.

103 pages. Components, Calling, Machine Switching, SxS, Long Distance. Contributed by the Connections Museum. Processing by Remco Enthoven and Paul Fassbender.

Extracts from the Bell System Technical Journal (April 1932) and several BSPs highlight reasons for adding capacitors to handsets.  BSPs referenced include C30.002, C32.203 and C32.275.  Contributed by Steve Cichorsky.

Contributed by Steve Cichorsky.  OCR by Clint Gilliland.

"Thousands Visit Kearney's Wonder Workshop," Telephone Review, Dec 38, Starts on page 7.

"Grooved handset article" from Bell Laboratories Record March, 1939? Vol. XVII No. 7, by T S Huxman, Insulating Materials Development.

Contributed by Jim Stettler.

Contributed by Steve Cichorsky.  OCR by Clint Gilliland.

Several internal memos discussing transmission and zoning implications of the new 500-type sets.  Includes a mention of the 4,000 unit 1949 trial and projected production quantities for the 500B:  50Q2 - 23K, 50Q3 - 49K and 50Q4 - 49K; and for the 401B: 50Q4 - 20K.  Price for a 500B = $14.30.  Also see AB43.910  Contributed by Clint Gilliland.

51 pages. Alexander Graham Bell Commemorative issue. Contributed, scanned and bookmarked by Steve Cichorsky. OCR by John Novack.