A search of newspapers for additional articles about the incident resulted in several hits which are shown in this screen shot from Genealogybank.com .
Five of the results are shown. The word "inst." has been circled in those clippings where it appears.
Partial screen shot of results from Genealogybank.com 20 November 2012 |
The January references all refer to the event as being on the 2d "ult." Obviously if the items are in January editions of newspapers the actual incident could not have taken place in February. "Inst." refers to the present month--which is what both January items use.
The last match makes it easy to see how the confusion between "inst" and "ult" came into being in some of the references. The last match is shows a 7 January date--most likely indicating that the item was copied from a newspaper in Herkimer County, New York, on 7 January. In that original article "inst." would have made sense.
Be aware of the difference between these two words, but make certain that you apply a little common sense as well.