I also think that there should be a liner or something else that is no longer there. This is why I think this may be the case: I have many years of personal experience using fountain pens and dip pens and use them most every day as my main writing instruments. A good fountain pen with a expertly made nib is nearly frictionless and I can write for hours with no hand fatigue. Dip pens are almost as good especially when you can use a high quality one such as a mother of pearl handle with a well made solid gold nib. Real fountain pen and dip pen nibs are miniature wonders of technology and refinement to work as an ink delivery system. On the other hand the solid glass dip pens you see from Murano and other places are terrible for writing as their nibs are not designed like a proper one - glass pens simply have an end that comes to a point with maybe a little decorative twisting of the glass or such. While they are pretty to look at they are very scratchy and do not hold much ink on the nib. They are mainly for decoration rather than actual use. Getting back to this inkwell, I believe it would most likely have had an insert or something because ink dries up fairly quickly if it is not covered or contained. It is formulated to dry quickly otherwise your writing would take forever to dry on the paper, even with a blotter. Having an uncovered inkwell would mean that you would need to dump out your ink and clean the inkwell every day or two whether you were using it or not as it would quickly become too thick to flow properly and then after a few days it would dry out. It needs a lid or cap or something like that to last longer. I is possible of course that this may not have ever had such a liner or lid but if that is the case my thought is that this inkwell likely would have been made a decoration to hold a pretty glass pen rather than being designed to be functional.