I'm someone who does some heavy note taking at desks that lack ink supplies. I always carry a back up pen. Still, I don't like having my #1 at the moment suddenly get caught short. Currently my primary pen is a Sheaffer Valiant Touchdown TM. It's a killer pen- but I will say I'm still trying to figure out the best way to check my overall ink level. I've found that using regular vertical checks isn't always a success for me- I find that by the time I see the level running low in the visulated section while holding the pen vertically with nib down, I'm too close to running out. When I see the top of the ink level in the visulated section I often have only a page or two of ink left. For someone with an ink bottle nearby (as people in the early 50s often had) this works fine. But for me it means I'll often just run out in the middle of note taking and that can be annoying or can allow me to fall behind.

So I guess that begs the question- am I missing something? Is there some way of holding the pen horizontally that will allow me to check the overall level of the ink in the pen (rather than only finding out when I'm very low)? It seems a little tough to have a meter for your gas tank that only kicks in when you're very close to E, rather than a meter that measures overall volume. Any one have tips as on getting an accurate measure of overall ink level using the visulated section as a guide?

(I will say I can tell the difference of a full and a nearly empty pen just by weight, but I'm trying to get an accurate assessment that won't leave me dry in the middle of taking notes in a live discussion scenario).

Buy more pens till you have another favourite!

I'll do a slow rotation, to see how quickly the bubble appears, but surface tension is not your friend in this regard. The only really useful windows I've run across are in my Wality and Osmiroid 75s-- piston fillers with giant reservoirs. With TM touchdowns and chubby vac fills, and with various Parkers for that matter, windows in other pens seem very much like the dose of tracers at the end of a machine-gun belt-- you are aware that running out is happening NOW!

Edit-- 'rotation' is a bit vague. While looking at the side of the pen, I'll move it from negative to positive pitch. Roll and yaw aren't so informative.

I have a visulated section in a '40s vintage Balance. I have experienced your problem. If you rock the pen back and forth a few times as you go through a load of ink and watch the bubble grow, you will get a pretty good feel for how much ink is left. You have to get the hang of it.

Paddler

The "quick and dirty" method is simply to fill it regularly and not wait for it to run out. You should have rough idea of how long you can go between fills (measure by pages, days, etc.) and routinely fill it when you get close to that point.

About a week is what I get out of a full fill. I have been in the habit of filling once per week for some time now- though I was curious as to whether I had missed something where the visulated section could help me find the level in the tank.