These are plans for making a spy periscope for the kids.
Mention of periscopes is quite common in the reports from European battle fields; such a device in a simple form can be made easily by boys who have fair skill with tools. The illustration shows a periscope which may be used for play, and has other practical uses as well.
In a store or other place where a person on duty cannot watch all parts of the establishment such a device is convenient in that it will reflect persons entering the door.
As a toy or for experimental purposes the periscope shown has many possibilities, and will appeal to youngsters.
It consists of a square box, 18 in. long, open at the ends. It is 3½ in. wide and made of wood, .375 in. thick. A mirror is fitted at an angle of 45° near one end of the box or tube, as shown in the sketch. The front of the mirror is opposite a three-cornered opening in the box which extends across one side. The opposite end of the tube is also fitted with a mirror in the same manner, except that the front of the mirror faces to the opposite side of the box at which there is also an opening.