If your query refers to William Greenlaw, progenitor of Greenlaw/Greenlow in Maine & New Brunswick, Canada:
According to "Annals of the town of Warren, Maine" by Cyrus Eaton, pub. 1851, a group of 60 Scottish emigrants left Scotland on the the brig Dolphin, Captain Cooters, master, in the summer of 1753. The ship touched at Piscataqua [Portsmouth, NH], where they remained for a week or more, and arrived in George's River [Maine] in September. Among the men listed by Eaton is " ____ Grenlaw," assumed to be "William Greenlaw" head of the Greenlaw household.