The first method of exposure was by means of blue print frames placed in the sunlight. The next step in the development of the present machines was the use of a single arc lamp. Later a bank of arc lamps placed side by side was employed. Since the convenience of operation seemed to fit into the reproduction field, mercury vapor tubes were utilized. It was later found that such tubes did not compare with arc lamps in the efficiency of printing.

Makers of Blue-Print Machines:

The C. F. Pease Company, Chicago, Illinois, and New York

City Paragon Revolute Corporation, New York City Shaw Blue-Print Machine Company, Newark, New Jersey

Photcntat Corporation. Providrncf. Rhodr Itland.

Photostat Machine with Engineering Board.

1. The Photostat is a machine designed for the rapid production of copy by means of

photography.

2. The subject matter is photographed directly upon sensitized paper without the intervention of any plate or film negative. Printed or written documents, drawings, blue prints, records, maps, fabrics, small tools, machinery parts, etc., may be copied in a few minutes at the cost of a few cents.

3. In addition to copying at original size, enlargements or reductions may be made in any

desired size. If enlargements required are larger than the maximum size sheet of the Photostat used, they may be made in sections and pieced together. Transfer negatives for reproduction by other processes are easily made on this apparatus. Standard models produce, on a single sheet, prints up to 18" x 24 ".