HISTORY OF TELETYPEWRITER DEVELOPMENT
R. A. Nelson
K. M. Lovitt, Editor
5555 West Touhy Avenue
The success of the modern teletypewriter began with Howard L. Krum's
conception of the start-stop method of synchronization for permutation
code telegraph systems. The purpose of this paper is to provide a
brief historical account of events which led to that achievement and
of those which ensued.
Four areas of development will be covered:
(1) The contributions of Sterling Morton, Charles L. Krum and
Howard L. Krum.
(2) The contributions of E. E. Kleinschmidt.
(3) The contributions of AT&T and Western Electric.
(4) The contributions of L. M. Potts
HISTORY OF TELETYPEWRITER DEVELOPMENT
Area I. In 1902 a young electrical engineer named Frank Pearne
solicited financial support from Joy Morton, head of the Morton Salt
interests. Pearne had been experimenting with a printing telegraph
system and needed sponsorship to continue his work. Morton discussed
the matter with his friend, Charles L. Krum, a distinguished
mechanical engineer and vice president of the Western Cold Storage
Company (which was operated by Joy's brother, Mark Morton). The
verdict for Pearne was favorable, and he was given laboratory space in
the attic of the Western Cold Storage Company.
After about a year of unsuccessful experimenting, Pearne lost
interest and decided to enter the teaching field. Charles Krum
continued the work and by 1906 had developed a promising model. In
that year his son, Howard, a newly graduated electrical engineer,
plunged into the work alongside his father. The fruit of these early
efforts was a typebar page printer (Patent No. 888,335; filed August
22, 1903; issued May 19, 1908) and a typewheel printing telegraph
machine (Patent No. 862,402; filed August 6, 1904; issued August 6,
1907). Neither of these machines used a permutation code.
They experimented with transmitters as well, applications filed in
1904 and 1906 maturing into Patents No. 929,602 and No. 929,603.
These patents covered modes of transmission which depended both on
alternation of polarity and change in current level.
By 1908 the Krums were able to test an experimental printer on an
actual telegraph line. The typing portion of this machine was a
modified Oliver typewriter mounted on a desk with the necessary
relays, contacts, magnets, and interconnecting wires (Patent No.
1,137,146; filed February 4, 1909; issued April 27, 1915). As a result
of the successful test of this printer, Charles and Howard Krum
continued their experiments with a view to developing a direct
keyboard typewheel printer.
They sought most of all to discover a way of synchronizing
transmitting and receiving units so that they would stay "in step."
It was Howard Krum who worked out the start-stop method of
synchronization (Patent No. 1,286,351; filed May 31, 1910; issued
December 3, 1918). This achievement, which more than anything else
put printing telegraphy on a practical basis, was first embodied (for
commercial purposes) in the "Green Code" Printer, a typewheel page
printer (Patent No. 1,232,045; filed November 28, 1909;issued July 3,
The transmitters first used by the Krums were of the continuously-
moving-tape variety. (A stepped tape feed, they maintained, would have
reduced transmission speed.) In order to permit sequential sensing,
the rows of code holes were arranged in a slightly oblique pattern
(with respect to tape edges). This method of transmission is more
fully elaborated in Krum Patents No. 1,326,456, No. 1,360,231, and No.
Keyboard-controlled cam-type start-stop permutation code
were developed by Charles and Howard Krum in about 1919. Such a
device is the transmitter component of the Morkrum 11-Type tape printer
(Krum Patent No. 1,635,486). This kind of transmitter employs a
single contact to open or close the signal line.
In about 1924 the Morkrum Company introduced the No. 12-Type tape
printer (H. L. Krum Patent No. 1,665,594). On December 23, 1924,
Howard Krum and Sterling Morton (son of Joy Morton) filed an
application on the 14-Type type-bar tape printer which matured into
Patent No. 1,745,633. 
Area II. It appears that the early efforts of E. E. Kleinschmidt
were directed toward development of facsimile printing apparatus and
automatic Morse code equipment. He patented first a Morse keyboard
transmitter (Patent No. 964,372; filed February 7, 1095; issued
January 11, 1910) and later a Morse keyboard perforator (Patents No.
1,045,855, No. 1,085,984, and No. 1,085,985). (The latter became
known as the Wheatstone Perforator.)
In 1916 Kleinschmidt filed an application for a type-bar page
printer (Patent No. 1,448,750 issued March 20, 1923). This printer
utilized Baudot code but was not start-stop. It was intended for use
on multiplex circuits, and its printing was controlled from a local
segment on a receiving distributor of the sunflower type. Later,
around 1919, Kleinschmidt appeared to be concerned chiefly with
development of multiplex transmitters for use with this printer
(Kleinschmidt Patent No. 1,460,357).
It seems that Kleinschmidt first became interested in modern
start-stop permutation code telegraph systems when H. L. Krum's basic
start-stop patent was issued in December 1918. Shortly after that
Kleinschmidt filed an application entitled "Method of and Apparatus
for Operating Printing Telegraphs" (Patent No. 1,463,136; filed May 1,
1919; issued July 24, 1923). The system described therein employed
the start-stop principle with a modified version of his earlier
multiplex distributor. That patent, accordingly, was dominated by the
Krum start-stop patent. The conflict of patent rights between the
Morkrum Company and the Kleinschmidt Electric Company eventually led
to a merger of the two interests.
Shortly after the new Morkrum-Kleinschmidt Corporation (later called
the Teletype Corporation) had been established, Sterling Morton,
Howard Krum, and E. E. Kleinschmidt filed an application covering the
commercial form of the well-known 15-Type page printer (Patent No.
Area III. Teletype entered the Bell System in 1930. From this
point on, advances in the Teletype product can be considered the
result of the pooled efforts of the AT&T Company, the Western Electric
Company, and the Teletype Corporation. Teletype Corporation, of
course, holder of the basic patents and expert in the art, was the
Although it appears from the report of R. E. Pierce, dated December
24, 1934, that the Bell System was active in the development of
telegraph printers and transmitters as early as the year 1909, a
review of the patents issued to Bell reveals no significant
contribution to modern teletypewriter development (using start-stop
permutation code) until the introduction in 1920 of the 10-A
teletypewriter (Pfannenstiehl Patents No. 1,374,606, No. 1,399,933,
No. 1,426,768, No. 1,623,809, and No. 1,661,012).
The 10-A teletypewriter was the first embodiment of such basic
design features of the 15-Type printer as stationary platen, moving
type basket, and selector vane assembly, but the majority of
improvements incorporated in the 15-Type were proprietary to the
Area IV. The earliest contribution of Dr. L. M. Potts to the
start-stop method of synchronization appears to have been set forth in
a patent application filed November 18, 1911, covering a reed-type
start-stop selector (Patent No. 1,151,216).
In 1914, Dr. Potts filed an application for a single magnet page
printer which used an eight-unit code (Patent No. 1,229,202; issued
June 5, 1917).
In 1915, Dr. Potts filed an application covering another single
magnet page printer, this one using the start-stop permutation code
(Patent No. 1,370,669; assigned to AT&T March 8, 1921).
Potts Patents No. 1,517,381 and No. 1,570,923 were also assigned to
 For anyone who is old enough to have seen a Western Union
where the typing is on narrow gum-backed tape that is moistened and
stuck to a telegram blank, this is the machine that produces that kind
of printing. The same mechanism is the basis of a typing reperforator,
a machine which punches received signals into a tape for retransmission
and also types on the tape so an operator can read it.
 This is the machine used until the 1960s or so by the news wire
services. Some radio stations still use a recording of the sound of
one of these machines as background during news broadcasts.
From: Jim Haynes <haynes@cats.UCSC.EDU>
Subject: History of Teletypewriter Development
Date: 17 Nov 91 08:34:46 GMT
Organization: University of California, Santa Cruz