My mother made me a scientist without ever intending to. Every other Jewish mother in Brooklyn would ask her child after school, So? Did you learn anything today? But not my mother. Izzy, she would say, Did you ask a good question today? That difference—asking good questions—made me become a scientist.
Isidor Isaac Rabi
At the beginning of 1877 the young 23-year-old self-taught mechanic Marshall Cram, working as the first foreman of the Mankato Manufacturing Company machine shop in Mankato, Minnesota, stumbled upon a problem. One of his duties was to keep books at night, which needed calculations, so wanting to make his work easier, Cram decided to create a calculating machine. By April 1877 his design was ready and on 17 April he filed a patent application. The patent was issued on 7 August 1877 (see US Patent No. 193853). Interestingly, the witness of the patent was Henry Tourtelotte (1839-1919), a prominent local merchant at Mankato, so we can easily guess another reason this machine was made.
The adding machine of Cram was similar to the later Centigraph of Arthur Shattuck from the middle 1880s. In contrast with Centigraph however, the device of Cram remained only on paper and never went into serial production, because the inventor didn’t have enough money to start the manufacture, and after 17 years the patent expired and was not renewed.
Just like other machines of this kind (so-called single column adders, e.g. that of Tito Gonnella), the calculating machine of Marshall Cram was intended to add a single digit at a time, i.e. the unit column is entered first, then the tens, the hundreds, the thousands, and so on, certainly a rather cumbersome task (as every partial sum had to be recorded on paper and the sum eventually performed), which greatly limits the usefulness of such devices.
The display capacity of the adding machine of Cram is 999. It is contained in an ordinary-looking box with an overall size of 10 x 18 x 11 cm and a weight of 0.650 kg. The machine itself is a small brass instrument with keys numbering from one to nine arranged in two rows. As one presses a key, it turns a flanged wheel a number of notches equal to the number imprinted on the key. This number is shown on the edge of the flanged wheel. For instance, if the operator presses the numbers three and six the wheel turns so that a small arrow is pointing to a figure nine.
The wheel counts only up to 100, so hundreds are shown on a stationary brass plate which has 100, 200, 300, and so on marked at the correct place so that one full turn of the flanged wheel, which has 100 digits on it, will draw the arrow from one to 100. Then, as the flanged wheel starts over from one again, the total sum is found by adding the sum of the flanged wheel and the 100, 200, 300, or whatever it is on the stationary brass plate.
It seems the adding machine of Cram remained only on paper, and never went into production. Only one example of the device (apparently the only prototype built by the inventor) survived to our time, as it was preserved by the descendants of the inventor (still living in Minnesota) up to 1996 when it was sold to an American collector, then it was sold to Arithmeum Museum in Bonn, Germany (see the nearby image). Interestingly, the model in Arithmeum differs somewhat from the patent version: the summing unit is installed on the left (instead of the right) of the keyboard, so obviously this example was made for left-handers. Amazingly, according to his descendants, Cram believed he had invented the very first adding machine and was disappointed when applying for his patent, he found out that he was to receive a patent for only an improvement in adding machines, so he was sufficiently discouraged to put the invention on the shelf, where it remained for 120 years.
The surviving machine appears to be made from a brass sheet. Actually, one of Cram’s patent claims was the use of a single sheet of brass in forming the entire base of the adder. The only part that seems to have been machined is the screw hub on the ratchet wheel. The machine is mounted into what appears to be a walnut or mahogany box.
Biography of Marshall Cram
Marshall Moses Cram was born on 2 June 1853 in Republic, Ohio. He was the youngest child of Moses Bailey Cram (born 17 October 1804 in Weare, New Hampshire—died 18 June 1878 in Faribault, Minnesota), and his first wife Rachel Amanda (Pond) Cram (born 19 Oct 1814 in Shoreham, Vermont—died 1854 in Scipio, Ohio). Moses Bailey Cram and Rachel Amanda Pond married on 18 December 1834, in Madison, Ohio, and had eight children: Martha Arnetta (1836-1917), Rachel Araminta (1838-1869), Abigail (1840-1844), Ellen (1842-1923), Mathilda (1843-1914), Charles (1846-1847), Elvira (1848-1850), and Marshall Moses (1853-1941). After the death of his first wife Rachel Amanda in 1854, Moses Bailey Cram married in 1855 to her younger sister—Lucy Clarinda Pond (1819-1865), and they had three children: Lilly Edith (1856-1914), Virgil (1858-1901), and Florence (1860-1862).
Besides the above-mentioned patent for a keyboard-driven adding machine, Marshall Cram was a holder of three other US patents (for a boiler cleaner (US634521) and for profile measuring and recording devices (US987863 and US1308580).
Cram spent almost entire his life in Mankato, Minnesota, where he used to work for Mankato Manufacturing Company, and in North Mankato, where he was appointed as the city engineer. As an engineer, Cram needed an instrument for surveying purposes, which inspired him to another invention—a surveying instrument, known as the sectograph. It was used for surveying roads and other land where comparative levels are wanted. The levels are shown by pin holes on a roll paper which reproduces the levels on the scale of one inch to 10 feet. In his spare time, Cram used to make little inventions for his home use, like a mechanical calendar device, lightning hook-up, signal device for the temperature of the honey (he was an apiarist), etc.
Marshall Moses Cram married Mary Grice (born 1 Oct. 1854 in Pennsylvania—died 25 Nov. 1939 in North Mankato, Minnesota) in 1875 in Minnesota, and they had two daughters—Martha Rubina (1880-1964), and Lula.
Marshall Moses Cram died on 16 July 1941 in Minneapolis, Minnesota, in the home of his daughter Martha, where he spent the last two years and was buried in Kerns Oak Grove Cemetery, North Mankato.
Note: Biographical information for Marshall Cram was kindly provided by Bri Krumwiede, an Archives Assistant of the Blue Earth County Historical Society, Mankato, MN.