The Prismatic Compass

About Charles Augustus Schmalcalder


In My Research and Information that I have been able to find, he was born on the 29th March 1781 Stuttgart, Neckarkreis, Wuerttemberg, Germany, and Christened as Karl August Schmalkalder on the 31st March 1781, his parents were Wilhelm Christoph Conrad Schmalkalder and Walburga Ruhlin, it seems that he anglicized it to Charles Augustus Schmalcalder when he arrived in England, Circa 1800's, established himself in London, and Married Anne Cochran in 1804, St.Andrews, Holborn, London, they had Nine Children, he was a Mathmatical Instrument Maker, He Started off his Business at 6, Little Newport St. St Annes, Soho, London around 1806, and had a Business at 82 The Strand, London around 1810 - 1826, later No.400 The Strand, London he stayed there until 1840 over the years he developed and patented several Mathematical Instruments, most famously The Prismatic Compass, there are a few of his Instruments still being displayed at the British Science Museum and various other Museums around the world.

He Died on 25 Dec 1843, Saint Martin In The Fields, Westminster, London, England at age 62,the Cause of his Death, was a few weeks prior he was run over by a Horse & Carriage and later died of his injurys in The Strand Union Workhouse, Castle St. (St Pancras)

His son John Thomas Schmalcalder carried on with this Business and stayed at 2 Fairfax's Court off 400 The Strand, London were he made Mathematical Instruments and Optical devices, where at one stage he was being listed as "Optician by special appointment to His Royal Highness Prince Albert", Over the years the name has altered, and often was spelt how it was pronounced and now is currently Smallcalder more information on his Page. He was apprenticed to Thomas Gilbert a Scientific Instrument Maker of the Grocers' Company, Nov. 5, 1829

The Schmalcalder Prismatic Compass

The prismatic compass was invented and patented by Charles Augustus Schmalcalder, a Mathematical Instrument Maker in London, in 1812 (Turner 1983, 257). As its name implies, it uses a prism, so that the angle could be read while the object was being sighted. 

Charles Augustus Schmalcalder registered Patent No 3545 on march 5, 1812 under the name "Philosophical Instruments", he was then granted an "Special Licence" by His Majesty King George III, which had a duration of fourteen years, The Patent expired on March 4th, 1826.

He lived and worked at these addresses:

6 Little Newport Street, St Annes, Soho London 1806 -

82 The Strand, London 1810 - 1826

Later went to 399/400 the Strand from 1827 -1839

He Retired in 1840


What is a "Schmalcalder Patent"?

Schmalcalder was not known as a Compass Maker.. indeed in his early days he was listed as an Optician so how did it become? Maybe being in the right place at the right time and having a ingenious concept of an idea, in so was an adaption to the compass for a sighting mechanism,The Prism, which in viewing through this and a sighting vane you could visually see the direction you were going, this adaption was a great leap from conventional Compasses and has lasted the test of time as it still unchanged since his invention, He was a very clever inventer of his time and the Schmalcalder Patent was undoubtedly the most important development in the history of compass making, with the obvious exception of the original invention of the compass. It is still used today unchanged on all the worlds finest prismatic compasses, used by the Military in nearly every country around the world today, and going back through time it was often mentioned in plotting routes around the new world land discovery's


Stick Barometers, Wheel Barometer; Pantograph; Surveyor's Compass; Prismatic Compasses, Terrestrial Globe, miniature, 1815, with case Reflecting Circle, Plotting Protractor Pantograph, Telescope, Theodelite, Sextant, Pocket Sextant, Microscope, Delineator


View Schmalcalders Patent Here

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