This is for Chris, and anyone else who might be able to profit from it.
A number of people with the surnames MATTERS (or METTERS) and SLEEP emigrated en bloc from Cornwall/Devonshire in the late 1880s. Based on a variety of sources, I have reconstructed the following account:
The emigrant party came from Devon and Cornwall. Members included:
John SLEEP (b. 1813) and his wife Ann SLEEP (née STACY, b. abt 1815) and their children John, Richard, Jane, Mary, and William
William MATTERS (b. 14 Sep 1831, d. 5 Mar 1901, son of Thomas Matters and Grace [Exworthy].) Susan Stacy MATTERS (née SLEEP, b. 1 Aug 1832, d. 7 May 1904; Susan was the sister of John, above)
According to the naturalization petition of William Henry Sleep (son of John and Ann, above), dated 29 October 1913, he [and, I believe, the rest of the party] left Plymouth, England, on 29 April 1857 on the vessel Cape Rogue, arriving at Quebec, Canada, then by Grand Trunk railway to Detroit, Michigan, arriving on U.S. soil on or about 5 June 1857 [possibly 1859--record is smudged].
They settled in Waukesha Co., Wisconsin.
P.S. Jacobstowe and Plymouth are both in Devon, not Cornwall.