If it's a hat badge then to understand that you need to know what hat it was worn on.
In all likelihood it was for a side cap which replaced the cavalry's badgeless pill box cap in the late 1890s and the Infantry's Glengarry. being Volunteers they may have done their own thing of course.
This was the 3rd's Glengary
https://www.regimentalbadges.com/upl...main_size2.jpg