This is not a facet of 19th century civilian life that you are likely to demonstrate, and only the most devoted of living historians would actually use historically accurate methods of coping with menstruation while at an event, but for your notes, or if you are asked by a particularly inquistive spectator, here are a few tidbits about 19th century menstruation.
First, let me say that it is hard to come across much information. This was not a subject casually discussed in the Victorian era. Based on letters and diaries, it would seem that the term "period" was in use at least as early as 1890, and may have originated from the phrase "periodic discharge" which which appeared on patent applications and in medical texts.
Like so many things, the discussion of periods and what to do about them seems to have been something mothers passed on to their daughters verbally, rather than consulting a book.
Apparently, this was not always done. Lydia Marie Child, an abolitionist and women's rights activist. wrote in her Mother's Book of 1831, that there was a "want of confidence between mothers and daughters on delicate subjects." Child recommended that girls of 12 should be given a "frank, rational explanation" of the subject. Ironically of course, Child's book provides no rational explanation itself.
So we can only imagine what a talk about menstruation between mother and daughter might sound like. We do have more information about what sorts of products were used.
The were called sanitary napkins even then, but back then it would have truly been a cloth napkin that would be washed and reused. They were held in place by a device similar to a T bandage, with a horizontal piece (the belt) holding a vertical piece (either the napkin itself or a holder for the napkin) which would fit over the crotch.
If you'd like to see a 19th century sanitary belt, there is one in the Valentine Musuem in Richmond, Virginia, which is very interesting. It shows the vertical piece attached to the horizontal piece with buttons. Other fastening methods included hooks and eyes or safety pins.
The pads themselves might be knitted, or made of linen, toweling, flannel, scrap fabric, cotton covered batting or even wood shavings (!) or natural sponge.
If nothing else, the popularity of white fabric for chemises and drawers would suggest that women did use something to absorb their menstrual flow.
This is one area in which I am sure that even the most stringent regiment would permit their members to "farb-out"!
