Robjohn brothers, William and Thomas, from Devon, England, had both worked as organ builders in England before emigrating to the United States. First in 1834 emigrated the younger brother—Thomas Robjohn (1809-1874), and started building pianos and organs. Then in 1857 emigrated the elder brother—William Robjohn (1803–1878).
Robjohn brothers were very good organ builders and mechanics, either in wood or metal. But they were inventors also—Thomas Robjohn is a holder of quite a few US patents for musical instruments, ink stands, road rammer, sewing machines tools, fluting rollers, and others. William Robjohn also is a holder of several patents—for pine organs, a liquid meter, and, which is important for us as computer-geeks :-), for a “new and improved arithmometer” (US patent Nr. 130244 of 1872). Besides the patent application, nothing is known about the calculating machine of Robjohn, so obviously it remained only on paper, and even the patent model of the device didn’t survive (up to 1880, the US Patent Office required inventors to submit a model with their patent application).
Let’s examine the elaborated calculating machine of William Robjohn, using its patent application, in which Robjohn claimed: This invention relates to a new adding machine, which is operated by means of numbered keys, and so arranged that mistakes cannot occur as long as the mechanism is in working order, as all keys are looked as long as any one is more or less depressed, and as the key depressed cannot be restored to its elevated position unless it has first been entirely pushed down. Errors that might arise from depressing some of the keys partly, and thus adding only fractions of the numbers which such keys represent, are thus entirely obviated, and rapid action, insuring absolute accuracy, can be performed…
The machine of William Robjohn is a single digit adding device (i.e. having the capacity for adding but one digital column at a time) and is the first key-driven calculator with a positive control.
In the illustration of the patent drawings of the machine can be noted that there are three sight openings in the casing through which the registration of the numeral wheels can be read. The numeral wheels are connected by devices for carrying the tens, one operating between units and tens wheel and another between the tens and hundreds wheel.
The units wheel (disk C), shown in Figure 3 (picturing a vertical transverse section of the machine), is connected by gearing to a long pin-wheel rotor (marked E), so that any rotation of the rotor will give a like rotation to the units numeral wheel, to which it is entrained by gearing.
To each of the nine digital keys (marked B), is attached an engaging and disengaging sector gear device, which, as shown in Figure 3, although normally not in engagement with the rotor E, will upon depression of its attached key, engage the rotor and turn it.
A stop device is supplied for the key action, which in turn was supposed to stop the gear action; that seems rather doubtful. However, an alternative device is shown in Figures 4 and 5 (picturing transverse sections, showing modifications of
the key-locking mechanism), which provides what may without question be called a stop device to prevent over-rotation of the units wheel under direct key action.
It will be noted that the engaging and disengaging gear device is here shown in the form of a gear-toothed rack and that the key stem is provided with a projecting arm ending in a downwardly projecting tooth or detent, which may engage the rotor E, and stop it at the end of the downward key action. While the stopping of the rotor shows a control in the machine, which takes place under direct action from the keys to prevent overthrow of the units numeral wheels, it didn’t prevent the overflow of the higher or tens wheel, if a carry should take place. There was no provision for a control of the numeral wheels under the action received from the carry of the tens by the transfer mechanism.
Biography of William Robjohn
William Robjohn was born in Tavistock, Devon, England, on 14 February 1803, to Thomas Robjohn (cognomen also spelled Robjohns or Rabjohn) (born 1772 in Buddle Cottage, Devon-died 1835), and Jenny Ann Luxmore (b. 1775). William was the eldest child, and had a brother Thomas (born 24 Sep. 1809, in Tavistock–died 22 July, 1874, in New York) and a sister Mary Robjohns (Wonnacott).
William and then Thomas served their apprenticeship under famous London based organ-maker John Gray and obviously were good apprentices, because after the training (which usually lasted 7 years) they had been invited to work for his company Gray and Davison (one of Britain’s leading organ-makers between the 1790s and the 1880s). Thomas soon left to seek his fortune in America, and in 1834 settled in New York, where he built many organs of his own, supplementing his income working for other New York organ builders. William remained in England until 1857 (working as foreman for Gray and Davison), when he and his family, at the insistence of his younger brother Thomas, also migrated to New York.
Between 1857 and 1863 Robjohn brothers worked together in New York City and Elmira, New York, and built several organs, characterized by splendid, carved casework, mechanical ingenuity and forward-looking tonal design. Since 1863 they worked for the organ-builder company J.H. & C.S. Odell. Robjohn brothers were inventive folks, and each of them obtained several patents, as William’s most valued invention (patent No. 54063 on 8 May 1866) was one of the first completely adjustable pneumatic composition movements for the organ.
William Robjohn was married to Harriet Robjohn (b. 1820) and they had three sons: Thomas, William James (3 Nov. 1843-21 Nov. 1920), and Frederic Fall (1855-1867). William James Robjohn (see the nearby image) became a famous US musician and composer (in response to his family’s opposition to a career in music, he adopted the pseudonym Caryl Florio in 1870).
William Robjohn died on 29 April 1878, in New York.