Sentence:  The use of the Hughes type <WSD>printer</WSD> is extending on the main circuits, where speed of transmission is a great object; but it is highly improbable that it will ever be adopted, except on main circuits. 
Meaning of the word marked with <WSD> tags:  A device, usually attached to a computer, used to print text or images onto paper; an analogous device capable of producing three-dimensional objects.