The history of this maker is strangely schizophrenic. It was begun in 1903 as an upper-end maker under the ownership of Marx Finstone, who also ran the Monroe (luxury), Marxton (mid-range) and Park Row (economy) pen companies. Eclipse was never quite the big name that some other pen-makers were, but were certainly competitive with the great names. In 1925, a Canadian wing of the company was opened, likely as a way of getting around import restrictions which lay between the US and the British Commonwealth; this was a trick Parker, Sheaffer and Waterman had all pulled.
Here is where the trouble in sorting out Eclipse begins. While a relatively high-end pen in the US, the Canadian factory made pens for all levels of the market (as well as pencils), meaning that one has to pay attention to the “Made in” part of the impression to know whether a pen is much to get excited about, and apparently the earlier US products seldom have a barrel impression because production was shared with Marxton and Park Row. Moreover, in 1929 Finstone died and his Canadian partner became more prominent in both the Canadian and US companies. 1929 also saw the start of the Great Depression, and it seems that the Canadian side of the operation weathered that economic storm rather more steadily than the American, possibly because of the greater depth of line. The two companies became essentially unconnected, and while the US wing stumbled along until 1962, the Canadian remained in vibrant production, buying up the parent eventually, and sliding into ballpoint production without great trouble.
The company is still in operation after a fashion, as a maker of advertising novelties; pens, pencils and other imprinted items.
Models I’ve examined, with more than usually approximate dating: