Page:The Riverside Press-1911.djvu/17



which is run an electric current. Here the copper fills in every crevice in the wax and forms an exact reproduction of the type. This thin shell of copper is then backed up with metal, making what is known as an electrotype plate, with a surface much harder than the face of the lead type and capable with careful handling of giving an almost unlimited number of clear impressions when placed on the printing-press.

These plates are then taken to the Electrotype Finishing-Room, where they are prepared for the presses. This process is one which requires great skill, for the surface must be perfectly even and smooth, and if any typographical errors or imperfections remain they must be corrected in the plate. Consequently, each page is examined by experts from another set of proofs (called plate proofs), which show the final state of the book before it goes to press.

During 1910 the accommodations of the Press Building were greatly enlarged by the addition of a new L-shaped building extending 228 feet to and 122 feet along Blackstone Street. It is a single story structure with large steel-sash windows on all sides and having