It's called the Fiddle Pattern. It was introduced in France in the 1760's. The iconic shoulders above the bowl were a later addition added to the pattern by the early 1800's. The pattern was the most common of the entire 19th century. Production of the fiddle pattern would be phased out by the early 1910's (start of WWI). Whenever you find that pattern you can almost guarantee it is 19th century. Most would have been silver plated originally, higher quality ones were most often 90% silver made from melted down coins, and known as "coin silver". In the USA they wouldn't have been stamped with their purity but often just the name of the smith or shop that produced them.