'Service Public' labels & The Postal Typewriter

I was intrigued by this William IV official cover for two reasons.  First, it features an uncommon postal label; second,  the addressee — ‘The Postal Typewriter’ — is unusual.

The cover was sent from Luxembourg-Gare, 11 June 1910, by the Grand Ducal Laboratoire Pratique de Bactériologie to 'The Postal Typewriter' in London, England.  The London oval backstamp dated 12 June 1910 and the laboratory's seal are seen on the back.  The 65-centime official franking pays the UPU registry fee (25c) and postage (40c for a second-step, 20-40 g letter).

1.  The Service Public label

From my philatelic colleagues in Luxembourg, I've learned that during this era government agencies could instruct the post office to frank their official mail with official stamps.  This was done by use of purple Service Public labels, which mandate in French: 

Affranchir au moyen de

Timbres Officiels

Administration des Postes!

Or, I'm told, sometimes 'S.P.' was simply written on the envelope, and official stamps would be pasted over the handwritten instruction.

Here's another example of the Service Public label used by the laboratory, now with its name in the cachet in German -- the Bakteriologisches Staatslaboratorium:

Properly pasted over the Service Public label, official stamps pay the registry fee (1.50 F) and postage (4.00 F) on a heavy, oversized (100-120 g) cover from Luxembourg-Gare, 4 April 1928, to Berlin, backstamped at Berlin-Schmargendorf on 6 April 1928.

2.  'The Postal Typewriter'

A postal historian can never be too curious.  Thanks to Google and Bing, I now know that classic typewriters are just as collectable as classic stamps.

One website —The Classic Typewriter Page  here — provides this account of the Postal Typewriter (and the photo shown above):

The Postal was an appealing portable typewriter that used an interchangeable hard-rubber typewheel and a three-bank keyboard with double shift. The Postal was invented by William P. Quentell and Franklin Judge. It was introduced in 1902 by the Postal Typewriter Company, based first in New York and then (1904) in Norwalk, Connecticut. It was made until 1908 or shortly thereafter.

The Postal originally sold for $25 ($27.50 with a veneered oak case) -- a nice price compared to the "standard" machines, which cost $100. The company boasted that theirs was "the only low-priced Typewriter combining Universal Keyboard, Powerful Manifolding and Mimeograph Stencil Cutting." With features such as these, the Postal enjoyed some popularity; the company employed 2,000 salesmen in the U.S., and the typewriter was exported to Great Britain, Germany, Austria, France, and even Russia.

And a news article from Norwalk, Connecticut, where the Postal Typewriters were manufactured, comments on a classic Postal Typewriter recently donated to the city's museum:

In the early 1900s, when the phone was not ubiquitous and telegraphs were inconveniently located outside the home, the mail, or the post, was convenient because messages were delivered three times a day. . . . With a Postal Typewriter, people could write a quick letter -- a post card -- and have it delivered by the day's end. . . .

Perhaps that's why Luxembourg's bacteriology laboratory was writing in 1910 to The Postal Typewriter.  Their letter was addressed in long hand.  I wonder if they later purchased a Postal Typewriter.  Covers in subsequent years might reveal the answer.  However, the laboratory's label shown below -- posted 12 May 1919 to Brussels with combination official franking totaling 1.40 F postage and registry fee -- is hand addressed!