increasing efficiency. The QWERTY keyboard introduced on the Sholes & Glidden typewriter in 1874 was designed for purely mechanical reasons and the chances of the keys striking each other and jamming was more limited with this configuration. Because the Blickensderfer used the typewheel, the "scientific" keyboard layout could be used for maximum typing efficiency. Models Model 5 The first widely successful production model was the Blickensderfer 5, introduced at the 1893 World's Columbian Exposition in Chicago. Production of the model 5 did not seriously get underway until 1895-1896. The 5 was the first portable, full keyboard, typewriter and came with the DHIATENSOR keyboard as standard or with a QWERTY keyboard available on request. Some of the earliest Blickensderfer 5's were sold in France as the Dactyle . The Blickensderfer 5 was the simplest of all Blickensderfer models and more were produced than any other Blickensderfer machine. About 74,000 or 37% of the 200,000 Blickensderfer typewriters produced, were No. 5's and their production continued until 1913, when other models became more popular. Model 6 and Featherweight In 1910 George Blickensderfer introduced the Blickensderfer 6, which was cast in aluminium and was essentially a lighter version of the Blickensderfer 5 which used cast iron. The aluminium version also appeared as the Blickensderfer Featherweight, which was an improved Model 6 with a backspace mechanism and the ink arm support was modified to an attractive curved folding design. These typewriters weighed only 5 pounds and were widely marketed as the Five-Pound Secretary. Model 7 The Model 7, first introduced in 1897, became the deluxe version of the basic No. 5 and was designed to please a greater cross section of the market. The biggest and most obvious difference was the wraparound space bar, which gave the machine a more solid and distinctive look. Blickensderfer also improved the paper scale, added black composite carriage knobs at both ends of the palten, added adjustable margin stops and a bell mechanism designed to be struck by a clapper attached to the inker arm indicating when the carriage was approaching the end of the typed line. The Blickensderfer 7 was also mounted on an oak base fitted with an attractive bentwood laminated oak case. About 63,000 Blickensderfer No. 7's were produced from 1897 until 1916. Blickensderfer Electric The Blickensderfer Electric was a revolutionary machine and was far ahead of its time when it was first introduced at the