|
|
|
|
|
|
Lawrence Secret Code Maker (toy) · 1939
The Lawrence Secret Code-Maker, also known as the
Dick Tracy Code-Maker, is a fully functional
hand-operated transposition cipher
in the shape of a linear wooden slide rule, sold from 1939
onwards as a children's toy by US slide rule manufacturer
Lawrence Engineering Service in Peru. 1
|
The device was intended as a children's toy — for the fun of secret
writing — and came with a comprehensive 16-page educational instruction booklet.
In reality however, it is a regular shift cipher, which means it
can be used just like any other
Vigenère transposition or shift cipher.
The device came as a pair of two identical slide rules — one for your best friend —
supplied in a carton box measuring 200 x 200
x 13 mm. Sold as an educational toy, it was available for the unbelievably low price
of 25¢ 2 making it hard to imagine how the company could survive on it.
|
|
|
Each device measures 195 x 28 x 9 mm and consists of two parts: a fixed
U-shaped piece, and a smaller movable part – the slider – that can be fitted
in the U-shaped cut-out. Both pieces are made of blank wood and are printed
with black ink. The fixed part is printed with Latin alphabets (A-Z)
and numbers (0-9). The slider is printed with the same alphabets (A-Z),
a row with reversed alphabets (Z-A) and a row with numbers (0-9). At the
bottom left, the unit is ambitiously marked as Patent Pending, but there
is no evidence that a patented was ever filed by Lawrence. 3
It can be used as a regular shift cipher, with a fixed shift, much like
the ancient Caesar Cipher,
but it can also be used a Reversed Caesar Cipher
by using the reversed alphabets at the middle row of the slider, in which
case the cipher becomes reciproke (reversible). Like other shift ciphers
it can also be used in other – more complex – ways, some of which are
explained in the booklet.
Apart from the basic configuration shown here, the same (or similar)
device was released as the BEICH Secret Code-Maker that could be won
by collecting Beich Whiz chocolate bar wrappers as part of a commercial loyalty
scheme. It came with a simplified 4-page booklet. It also surfaced
as the Dick Tracy Code-Maker — named after a popular comic strip book
character — which came with a simpler 4-page version of the
manual. That version is shorter than the original one.
|
 |
-
At the time Lawrence Engineering Service
was based in Peru, Indiana, USA.
-
Equivalent to approx. US$ 4 in 2016.
-
Being a well-known principle, any patent would probably
have been declared invalid due to prior art.
|
|
A shorter version
— 6 inches (155 mm) instead of 7.5 (195 mm) — was released in 1961.
It was stamped Dick Tracy Secret Code Maker, and was named after the popular comic
strip book hero Dick Tracy, created in 1931 by Chester Gold [3].
Like the 7.5" version, it was made by Lawrence.
|
|
The Dick Tracy version was distributed by the Chicago Tribune New York News Syndicate
as a promotional item. It was sold as a single unit – not as a pair –
and came in the simple carton packaging shown in the image on the right,
along with a 4-page version of the manual
[B].
|
|
|
|
|
Lawrence Engineering Service
|
|
|
Lawrence Engineering Service was a 10-person company, established in 1935
in Wabash (Indiana, USA) and owned by George Lee Lawrence and his wife
Vivian C. Lawrence.
The company was well-known for the manufacturing of affordable wooden
slide-rules for a variety of purposes, such as mathematics, topography, photography,
units conversion, engineering, chemistry, music, etc. [1].
In 1938, the company moved to Peru (Indiana), where it existed under
the same name until 1947. In that year, after a divorce of the two owners,
the company went on as Engineering Instruments, owned by Vivian C. Bozarth
(formerly: Lawrence) and her new husband Rev. Frank H. Bozarth.
The company existed until everything was destroyed by a major fire on
5 July 1967. Despite the fact that the company was insured, it was decided to
close down the ailing business altogether [2].
|
1935-1938 Lawrence Engineering Service, Wabash, Indiana (US) 1938-1947 Lawrence Engineering Service, Peru, Indiana (US) 1947-1967 Engineering Instruments, Peru, Indiana (US)
|
For a complete account on the history of Lawrence Engineering, its directors
and the many different types of slide rules that were manufactured by them,
please refer to
The Unique Lawrence,
written by David Rance and first
published in 2011 for the Oughtred Society
[2].
|
- Make your own Secret Codes in a Flash
Lawrence Engineering Service, Peru, Indiana, USA. 1945.
- The Dick Tracy Secret Code maker
Lawrence/Chicago Tribune, 1961. 4-page booklet.
|
|
|
|
Any links shown in red are currently unavailable.
If you like the information on this website, why not make a donation?
© Crypto Museum. Created: Tuesday 12 June 2018. Last changed: Sunday, 05 May 2019 - 20:00 CET.
|
|
|
|
|
