This informative passage about the Hammond’s keyboard comes from one of the companies catalogues.
“The original, or Ideal keyboard, circular in form, was designed solely with the view to obtaining the greatest ease and celerity of manipulation. Removed from the limitations which the danger of colliding type bars imposed on other machines, the arrangement of keys was only governed by questions of convenience and speed. The most commonly used letters are placed in the centre of the keyboard, with due regard to their natural sequence in the formation of words, and also to the superior dexterity of the right hand. This keyboard has the now famous square, black keys, the nearest and only approach to the piano keyboard possessed by any typewriter. This is the keyboard that eminent oculists and experts have proclaimed to be free from the injurious effects upon the eyesight wrought by the small, glittering key buttons used on other typewriters.”
The letterhead below has a wonderful port view of the Hammond Factory. Be sure to see the enlargement.