I really shouldn't post when it's late
I miss too much important detail......like how to establish a date.
Not much more awake this morning and I know there are others here with much deeper info actually stored in their brains, but came across this slightly informative tidbit. As you mentioned, they were taken over (rather, formed a coalition with) Internation Silver along with many other companies. But they did not cease to exist.
The individual companies maintained separate identities, significant for those seeking to identify antique silver. When you're looking at antique silver, keep in mind that initially the companies that joined International Silver Company did not use the standard mark of the company as a whole. Instead, the individual companies continued to use their identities and marked silverware with their own touchmarks. Only products sold by International Silver as a parent company used the International Silver mark.
http://www.ehow.com/about_5065999_history-international-silver-company.html#ixzz1XpgshU3O"The individual companies maintained separate identities, significant for those seeking to identify antique silver. When you're looking at antique silver, keep in mind that initially the companies that joined International Silver Company did not use the standard mark of the company as a whole. Instead, the individual companies continued to use their identities and marked silverware with their own touchmarks. Only products sold by International Silver as a parent company used the International Silver Mark"
This doesn't help with giving you an actual date, but does tell you that Simpson Hall Miller were still using their mark after 1898.
Will hunt up some caffeine and see if I can come up with more. In the meantime, wait for someone who knows what they're talking about.