All About Inventions and Discoveries
The Romance of modern scientific and mechanical Achievements

194 All About Inventions then pressed upon the paper by means of a knob. This type of machine is very simple, occupies very little space, and is light in weight. But it is slow in operation, and has virtually disappeared from the commercial world. Finally, there is the type-wheel machine founded upon the principles of the Pratt and Hammond typewriters, in which the type is mounted, or cut upon the face or rim of a wheel, which is revolved by depressing the key to bring the required letter to the printing point and then smartly depressed upon the paper. The Hammond and Blickensderfer machines offer probably the most illuminating examples of this system. But it is the type-bar machine which reigns supreme to-day. It is not only fast in working, but being of substantial design and construction, is able to stand up to the hardest work. The typewriter industry underwent a tremendous impetus upon the expiry of the Remington master patents, which, up to that time, thwarted competition. At the moment discussion rages around the respective advantages and disadvantages of the single keyboard with shift-key and the double keyboard. But, generally considered, it is probable that the shift-key system has the greatest number of supporters. Some idea of the arduous task with which the pioneers were confronted in the early days, and an illuminating impression of the widespread success and popularity of the typewriter at the moment, may be gathered from the fact that the total sales of the Remington typewriter during the first ten years of its history—1874 to 1884—scarcely equalled the sales of a single month at the present time. In