Enos Ropp (1869 - 1904) spent his childhood in Hudson, Illinois, the son of Christian and Magdalena Ropp. But the family moved to Chicago where Christian Ropp was involved in publishing a newer edition of his Ropp's Commercial Calculator and Ropp's Rapid Calculator sometime prior to 1892 when Enos registered as a voter in Chicago. Enos received his education at a Bloomington business college and ISNU and was apparently assisting his father in his mathematical work in 1893.
In February of 1893 Enos Ropp was not doing well and was sent to Bloomington for a rest with his relatives here. He was apparently exhausted by his worries over his father's new rapid calculator and was suffering from insomnia. Enos had been in Bloomington only four or five days when he became much much worse and began to be "violent." Christian Ropp travelled to Bloomington to assist his son and took him to the county court where Enos was committed to the insane asylum. His behavior was described in the Pantagraph:
His behavior was very noisy and his cries and shouts attracted much attention. He constantly talks and lectures on scientific subjects and claims to have made some wonderful discoveries, which of course only exist in his imagination.
By 1900 Enos was living at his home in Chicago once again, per the census of that year. During that time he frequently visited Normal, where his sweetheart, Jessie Johnston, lived. But in 1904, Enos was apparently once again disturbed and sought treatment in Madison, Wisconsin. On May 23, 1904 he fell beneath a train, in what was speculated to be a suicide. Some reports had suggested that he was in distress because his fiancee had thrown him over. Jessie Johnston was quoted in the Chicago papers as being hysterical with grief and insisting that she would attend the funeral to prove that she was always in love with Enos and that he had not committed suicide, but had died by a terrible accident.
The Calculator was in publication from 1875 to 1919 and was a "million seller" by some accounts. A "calculator" collector describes the Ropp Calculator this way:
The Ropp booklet is full of useful mathematical information, methods and tables spanning 128 pages. And it does some stuff that a Pentium machine user would be hard pressed to do - like computing the price of batches of hogs, cattle, grain, and other commodities. As the "Manufacturer and Builder" magazine stated in a review in its December 1890 issue, this "condensed vest-pocket book" contains "tables for the use of cattlemen, grain handlers, cotton dealers, farmers, grocers, and others, which will spare them much time and trouble, and many a headache". Just what we're trying to do today with our modern computers, to varying degrees of success... The names of the tables provide an intriguing peek into the commercial world of another age. They include "Table throwing the Weight of GRAIN, seeds, &c., into Bushels and Odd Pounds", "Millers' and Farmers' Exchange Table", "Table showing the value of Baled COTTON", "Ginners' table, showing the Toll of COTTON", and "Table showing SPECIFIC GRAVITY of well known substances", the latter including Ale, Beeswax, Gum Arabic and Lignum Vitae.