in the Massachusetts, Birth Index, 1860-1970
in the 1940 United States Federal Census
This William's father is Oscar Pike Martel.
in the New Hampshire, Marriage Records Index, 1637-1947
in the 1930 United States Federal Census
in the Massachusetts, Death Index, 1901-1980
I have lots of information on Albert! I have none for William also my other Uncle Leo J Martel born 1903 was living in Winthrop with his Wife Ruth. In the 1930 Census along with Winthrop he was also listed at Fort Banks. No information after 1930 Census.
Here's a link to the image at FamilySearch: https://www.familysearch.org/ark:/61903/3:1:33S7-9R74-9K4C?i=15&cc=1810731
It definitely looks like Mellen, William, just above Martel, Albert M. FamilySearch accounts are free, and highly recommended if you don't already have one.
The transcription says Martel but that is not what the image says. Someone making the transcription made an assumption and "corrected" what they saw. It is possible that the original copy of the census said something different but its whereabouts would need to be fdetermined and documented. The official copies sent to Washington were transcribed from the enumerators master copy. Those originals sometimes still exist.
I'll have to spend some time on my Martel cousins. I had their connection wrong. They are connected in my LaFlash/LaFleche line and were mostly in Rhode Island.