In an earlier post, I noted that early 20th-century astronomy’s demand for number-crunching prompted the Van Vleck Observatory’s first director, Frederick Slocum, to set aside two rooms in the observatory specifically for “computing.” These rooms would presumably have been occupied by human “computers” who would perform the intricate calculations needed to figure out stellar distances.
The human computers were not unaided, however. It appears that Slocum purchased a mechanical calculator in the fall of 1915, soon after his arrival at Wesleyan. The device’s unforgettable name was the “Millionaire”:
This thing looks like a millionaire might own it (although from browsing the web it sounds like it was mostly banks and insurance companies that purchased them). Note the mahogany case; the gleaming chrome knobs; the black lacquer top plate. And it works beautifully, despite being over a century old! It still adds, subtracts, multiplies, and divides with a twirl of its well-oiled gears.
Addition and subtraction are dead easy, as is multiplication (apparently, the Millionaire’s key advantage over earlier calculating machines was that it multiplied directly via a special gear, rather than forcing the user to add repeatedly.) Division is a little trickier: you essentially must guess the digits in the quotient as in pencil-and-paper long division, although the machine helps immensely by computing the remainder for each subsequent round of quotient-guessing. (Computers still aren’t particularly good at division, even in the age of microprocessors.) For more on how to use the millionaire (not to mention instructions on how to take it apart) see the amazing material at John Wolff’s Web Museum.
Slocum’s correspondence with New York-based W.A. Morschhauser (who sold the Swiss-made Millionaire in the United States) suggests the relative cost of the machine. It wasn’t quite a supercomputer — but even in those days, Millionaires didn’t come cheap.
The least expensive hand-cranked model could handle six-digit numbers and cost $280 ($6,615 today, per BLS statistics). The top of the line could handle 10-digit numbers and cost $665 (over $15k today). Slocum purchased the 8-digit model that would have been $364 ($8,600) new, but it seems that being a thrifty New Englander, he opted to get a factory-refurbished one for $275 (or about $6,500).