I checked that in vol. 3 of the 20-volume Oxford English Dictionary, my proudest material possession. You are right. Up to at least the 1850s, as supported by the extensive corpus of citations in the OED, "computer" meant "a person performing computations". The first solidly documented occurrence of the word as "machine performing computations" is from 1897; from 1915 on, the word is only found in this sense, i.e. the sense of "person performing computations" has then fully disappeared, in a period of only 18 years.
Interesting. You made me discover something I did not know. Thanks.
"Computer", actually, has the meaning: "Machine that performs computations". In that sense, this contraption truly is a computer. It probably only has a memory size of only a few bytes, in modern terms, and can only do a few FLopS also. Yet, it is a computer, in all senses of the word.
Funny. I always thought of Michelson as of one of the two guys involved in the "failed" mirror experiments that allowed A. Einstein to come up with the theory of Special Relativity. Not so, it turns out now: the guy was an accomplished engineer. How great.