The Metroscope

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

rfect 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.