This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
589. Enlarging-lanterns are constructed for use with artificial light. Either electric, gas or kerosene lamps can be used. Illustration No. 8 shows the Ingento Enlarging-Lantern. The end of the apparatus containing the lantern is fitted with large Russian iron light chambers which accommodate any of the artificial lights you may wish to employ. The bellows and lens-board move on rigid and finely nickeled rods. The frame-stage which receives the negative-carrier is open on the top so that it can be used with negatives larger than those to which the lantern is especially adapted, and as it is perfectly square the negative can be used vertically or horizontally.
590. The condensing lenses are located between the negative-carrier and lantern. When using the enlarging-lantern all that is required is an ordinary room made perfectly dark, a table upon which to place the lantern, and another small table upon which to place a good sized box to be used as an easel, which will support the sensitized paper. The side of the box facing the lantern should be covered with white cardboard, which may be marked off with a pencil in various sizes, 8 x 10 to 16 x 20 inches. These markings or guides will aid you to obtain the correct size enlargement desired.
591. To operate the instrument, light the lantern and then place the negative in the negative-carrier. Place the table containing the box which is to carry the Bromide paper (and which hereafter will be referred to as the easel) within three feet of the lens and directly in front of and square to it. To obtain a focus, rack out the bellows until the image appears sharp on the white card on the easel. If the image is too small place the easel farther away. The size of the image depends upon the distance between the easel and the lens.
Illustration No. 8. Ingento Enlarging-Lantern. See Paragraph No. 589.
592. When you have obtained the focus, cap the lens and with thumb-tacks attach the Bromide paper to the easel. You are then ready for the exposure, which will vary from 20 to 60 seconds according to the light employed and quality of the negative used.
593. After the exposure the print is removed from the easel and is ready for development, which we will treat of later.