I'm struggling to make sense of the word inst. and the long dashes — in this excerpt from E. Nesbit's The Railway Children. The excerpt is part of a letter that the children receive. The dashes are actually em dashes, with no space before or after.
It is proposed to make a small presentation to you, in commemoration of your prompt and courageous action in warning the train on the—inst., and thus averting what must, humanly speaking, have been a terrible accident. The presentation will take place at the—station at three o'clock on the 30th inst., if this time and place will be convenient to you.
I read online that inst. is an abbreviation for instante mense, or current month. Thus the writer is inviting the recipient to a ceremony on the 30th of the current month. That has been made clear through a Google search. But how are we to interpret the first occurrence of inst? Is the long dash to mean that the writer doesn't know the exact date? Or are we to assume that the letter was damaged in transit and is illegible? And furthermore what might have possessed Nesbit to make this decision (as the exact dates are not of particular importance to the story)?
For the second dash, what purpose can the em dash between the and station mean? There is clearly only one station that the writer could be referring to.