Fawcett Plumb

Fawcett Plumb

On 17 June, 1881, Fawcett Plumb (1834-1919), a businessman, politician and prolific inventor from Streator, Illinois, (see biography of Fawcett Plumb), applied for a patent for keyboard adding machine. The patent (see US patent 256591) was granted in April, 1882. Besides the above-mentioned patent, Plumb was a holder of several other patents (at least 6) for various machines, like device for fastening roof tiles, kiln for burning bricks, ditching machines, twin cylinder single acting engine, etc.

After the three first key-operated calculating machines in the world, invented in Europe (see machines of James White, Luigi Torchi and Jean-Baptiste Schwilgué), there are a number of patents issued in the United States on machines of this class, starting with devices of Parmelee from 1850, Hill from 1857 and Winter from 1859.

All of these machines varied in construction, but not in principle. Some were really operative and others inoperative, but all lacked what may be termed useful capacity. Such machines, of course, never became popular because of their limited capacity, which required many extra movements and caused mental strain without offering an increase in speed of calculation as compared with expert mental calculation.

Let’s examine the adding machine of Fawcett Plumb, using the patent drawing (see the patent drawing below).

The machine is a simple column adder (for adding up columns of figures). The principle upon which the device is constructed consists in the revolution of a disk peripherally encircled by a series of numbers running from 0 to 99 through arcs of circles embracing from one to nine numbers by means of nine keys transmitting motion through a system of suitably-arranged levers.

Fawcett Plumb

Fawcett Plumb’s patent drawing

Marked with is a case, adapted to inclose the working parts of the instrument. It is provided with a removable convex cover, , which is perforated to expose a small section of the peripheries of the units and tens wheel and the hundreds-wheel . Pointers and , attached to the said cover, designate the numbers on the wheels and respectively. The units and tens wheel is mounted on a shaft, , which longitudinally traverses the case , being journaled in each end thereof.

The hundreds wheel , encircled by a series of figures running from 1 to 10, is mounted on a short shaft, , journaled in one end of the case. The said shaft also supports a cog-wheel, , provided with ten cog-teeth, with which a cam, , rigidly secured to the shaft , is adapted to be engaged to move the hundreds-wheel one-tenth of a revolution to every complete revolution of the units and tens wheel (thus performing tens carry).

Ten revolutions of the units and tens wheel are required in the regular operation of the instrument through the keys to effect one complete revolution of the hundreds-wheel. However, to facilitate the operation of setting the instrument, the shaft is provided with a thumb-nut, , by means of which the wheel can be revolved independently of the system of levers and keys, and the short shaft is provided with a thumb-nut, , whereby the hundreds-wheel may be revolved independently of the cog-wheel and cam

image

Previous articleWilliam Prehn Quentell
Next articleReuben Rodney James

More from author

Related posts

Latest posts

USENET Explained – Everything You Need To Know

6 Facts about USENET USENET was popular and used before the World Wide Web and internet browsers were easily accessible to the general public and...

RSA Encryption Explained – Everything You Need To Know

The world runs on communications. From ledger checking and balancing to pen-pals, everyone has a need to transmit information. Unfortunately, not everyone is trustworthy...

Simple Mail Transfer Protocol Explained – Everything You Need To Know

6 Facts about Simple Mail Transfer Protocol Simple Mail Transfer Protocol, or SMTP, was one of the first commercially available protocols that determined how electronic...

Want to stay up to date with the latest news?

We would love to hear from you! Please fill in your details and we will stay in touch. It's that simple!