Frederick A. Draper.

Those interested in wireless telegraphy experiments who have not learned the Morse code, and yet desire to transmit messages, can do so by means of the simple arrangement here described, which closely resembles the original device used by Prof. Morse in the early days of telegraphy.

A frame made of plain picture-frame moulding should be purchased. The inside measurements should be about 6x8 in. A piece of sheet brass is then cut to fit inside the frame, in the same way that a piece of glass would be fitted for a picture. Also a piece of 4-ply white Bristol cardboard of the same size is cut, and then on one surface marked lightly with a pencil to show the inside edge of the frame.

Across the cardboard in the longer dimension draw lines with India ink, the first one 3/8- in. from the line showing the edge of the frame, the second one 1 1/8 in. from the first line, then 3/8 in. followed by a 1 1/8 in. space, etc., marking off four spaces of each width. With the first narrow space at the top, mark lightly with a pencil a vertical line, 1/2 in. from the line showing the left edge of the frame, and nine other lines 1 3/16 in. apart. On either side of these ten lines make other pencil lines 1/8 in. away, forming spaces 1/4 in. wide.

Directly over the centre lines just mentioned and in the 3/8 in. space across the sheet, mark in India ink the figures and letters as shown in the illustration, this being a typewriter arrangement to avoid the excessive movements that would be required by an alphabetical one. The lettering should be heavy that each character may be easily read. Holes are then cut through the cardboard under each character with a sharp knife, the sizes varying to represent the dots and dashes. The horizontal ends of the holes should be on the lines on either side of the centre line under the letter, making them uniformly 1/4 in. long. The vertical length must be carefully marked out to a uniform scale, that for a dot being of unit length, and a unit of about 3/32 in. will, on the longer letters, require all the available space. The spacing should be marked out as follows :

Also, when using the transmitter, the spacing between words should be a time interval represented by six units. To illustrate the unit spacing, take figure 1 at the left end of the top row comprising dot, dash, dash, dot: - for the dot cut a hole 3/32 in. long; 3/32 in. below this hole cut another for the dash 9/32 in. long; 3/36 in. below this cut another for the second dash of the same length, and 3/32 in. below this a hole 3/32 in. long for the second dot. The top edge of the upper hole of each character should be but on the cross lines under each character. When all the holes have been cut a stencil is formed which is then given a coat of spirit shellac on each side, that on the under side being put on last and as quicely as possible, so that, while the shellac is still moist, the stencil can be placed upon the sheet of brass, smoothed down to get a firm contact, and allowed to dry in position. In a short time the stencil will be found firmly united to the brass, which may be seen through the holes. Should any shellac work out into the holes it should be removed with the point of a knife. The stencil and plate are then put in the frame and fastened the same as for a picture.

Two binding posts are now mounted on the upper edge of the frame, the base of the one on the left being connected with the brass plate, that on the right with a piece of flexible conductor, the other end of which is put through a cork pen-holder with about one inch of the conductor protruding at the lower end. Enough of the wire from a piece of the conductor is cut into short lengths and formed into a brush at the end of the pen-holder, by winding a number of turns of wire around the base of the brush, and the transmitter is complete.

To use it, the line wires are connected to the binding posts, the brush is carried across the holes under the characters with slow, steady movements, the circuit being completed when on the brass and broken by the cardboard strips between the holes. A little practice will enable anyone to send an accurately spaced message. A description of a tape receiver operated by clock-work will be given at an early date.