The first to introduce glass cartridges to the public was the Eagle company way back in 1890.  The idea was not a resounding commercial success and it was not until 1936 that it was revived by Waterman, France.  The first glass cartridge Watermans were converted American-made pens but later Jif-Waterman went on to produce designs of their own.  World War II halted production of these pens but it was resumed after the war, one example of the new models being the Duo 7.

It was advertised as being “the most perfect pen in the world”, but goodness knows, that’s been said often enough about almost every pen that ever came on the market.  It was also said that it was safe to fly with it and that it was reversible, one side of the nib giving a thinner line than the other.  In France it cost Fr.7.550 and in Britain 84 shillings, which is £4.4 shillings or four guineas, just to confuse those of you who are used to decimal currencies.  For that you got a barrel with an exceptionally long blind cap, a nice large 18 carat number eight Waterman Ideal nib and a double rolled gold cap.

It’s a superb pen by any standard.  The build quality is very high and in the case of this example, the original cartridge seal is still in good condition.  When they perish, the seals are quite easy to replace.  The glass cartridge can be refilled an infinite number of times.  Not that you’ll have to do it all that often.  By modern standards, it’s a huge cartridge.

The pen has a push-on cap which catches on the gold-plated ring between the section and the barrel.  It works very well.  I assume that one would normally remove the blind cap to fit a new replenished cartridge though the section unscrews as well.  There is a spring mechanism in the butt of the blind cap which forces the cartridge into place.  If you’re one of those people who is devoted to soaking pens, remember that that’s there and it will rust and break in no time at all if it’s soaked.  This section is ribbed, giving a secure grip and the feed is one of the patent Waterman complex multi-finned type.

In use, the nib, like most 18 carat nibs I have come across, is no more than semi-flex.  The nib is truly reversible and writes perfectly well on either side.  I don’t know if it really is “the most perfect pen in the world” but if not it’s a pretty good runner-up.