Comprises a series of squares accurately engraved upon the finest plate glass by machinery. The two plates of glass (of which one form of the instrument consists), are ruled for convenience with squares differing in size. These are framed and held together by thumb screws, allowing sufficient space between them for inserting and securing a picture the size of a cabinet photograph. The lines are thus brought into such perfect contact with all parts of the photograph so that they appear to be drawn on it. One feature of this instrument which renders the square system very practical, consists of the division and sub-division of the squares by dotted lines and dash lines. The eye naturally divides a line or space into halves and quarters, and for this reason the dash lines have been designated for quartering the main lines, and the dotted lines for quartering the squares thus formed. This gives sixteen times as many squares for use as are drawn upon the photograph.
A method based on the same principle as the metroscope, but not requiring the use of that instrument, may be pursued, as follows: Fasten the photograph to a board, mark the space at the top, bottom and sides into one-quarter inch divisions, and drive sharp pointed pins in each of the division marks. Taking a spool of white thread run it across vertically and horizontally from each pin to the one opposite, and you will then have the photograph divided into one-quarter inch squares; then, if your enlargement is to be six times the size of the photograph, take the mounted crayon paper and divide the sides and top and bottom in 1-1/2 inch squares, run thread across the same as for the photograph, and then proceed to draw the outline, first in charcoal, and afterwards with the crayon. The spaces marked on the crayon paper should in each case, of course, be as many times greater than those marked on the photograph as the intended enlargement is greater than the photograph.
THE PANTOGRAPH.
This instrument for enlarging or reducing a picture was invented about the year 1603. It consists of four metallic or wooden bars or rules, which are perforated by a series of holes (numbered from 1 to 20), and connected together by means of an adjustable thumb screw. The instrument is provided with a tracing and a marking point, and a screw or point which is forced into the drawing board to hold the instrument in position. A good pantograph will cost about two dollars; those of a cheaper grade are entirely worthless for practical use, while a good one will last a life time. A little experience will enable any one to learn the use of the numbers.
To employ the instrument select the number on the bars corresponding to the number of times the subject is to be enlarged, and connect the adjustable ends of the bars so that they intersect at this number; secure the pantograph to the drawing board at the left hand side; place a piece of manilla paper at the other end of the board and secure it with thumb tacks, taking care to smooth all the wrinkles out. Next adjust the marking point in the centre of the paper; and secure the photograph to the board so that its centre shall be directly under the tracing point, which should always touch it. If it does not do so at first, place a little weight on the instrument over this point heavy enough to bring it in contact with the photograph. Now guide the instrument, by taking hold of the tracing point while at the same time you watch the marking point. In this manner go over the entire photograph, putting in all the details necessary, after which you can transfer this outline to the crayon paper by means of the tracing paper according to the former method given for transferring an outline.
These are all the best methods of producing an outline. In each of them you fasten the charcoal lines with the No. 2 crayon points, and then, having brushed off the charcoal, proceed to put in the background for your portrait. This you do by any one of the methods given in the following pages.