762 



Popular Science Monthly 



flying, undoubtedly to spy out the land 

 and to see that no enemies are in the 

 vicinity. This characteristic of all birds 

 is taken advantage of in this device. A 

 sprig, top of a fence post, brick or stone is 

 fastened to a short 

 movable arm 

 which is in control 

 of the electric con- 

 tacts. These con- 

 tacts are adjusted 

 so that the feath- 

 ery, light body of a 

 bird readily presses 

 the movable arm 

 downward thus 

 closing the cir- 

 cuit which releases 

 the shutter of the 

 camera and the 

 picture of the shy creature is secured. 

 The construction of this apparatus is 

 very simple indeed, as can readily be 

 seen from the diagram. An empty cigar 

 box was used for the house. This was 

 securely fastened to a comparatively 

 thick base. Long strips of iron, 3^ in. 

 wide and 1 16 in. thick, were used. Out 

 of this the support A was made as shown 

 in the illustration. This projects about 

 1 in. above the cigar box, a hole B was 

 therefore bored. Two holes, C and D, 

 situated about }4 in. above the top of the 

 box, were drilled into the iron A. The 

 arm E was- then made. This projects 2 

 or 3 in. beyond the box. This arm also 

 has two holes cor- 

 responding to C 

 and D. A nail is 

 loosely passed 

 through these 

 holes. This forms 

 the axle or pivot 

 for the arm E. 

 The arm flaps are 

 bent together and 

 fastened with a 

 U-shaped clip at F. The arm carries a 

 block of wood G which is fastened just be- 

 yond the edge of the box so that it does 

 not come into contact with it. To this 

 block a wire // is attached which holds a 

 piece of metal (copper preferable) cut 

 as shown. The loop / lets the metal ./ 

 touch both poles, K and L, which con- 

 sists of two brass wires 5 in. long. The 

 branch M upon which the bird hops, is 



Box enclosing ail the mechanism which con- 

 trols the electric switch for making contact 



Diagram showing connections for the elec- 

 tric circuit and metal connector in the switch 



pressed down. Another piece of metal, 

 -V, attached at extends to within a few 

 inches of the bottom of the box. This is 

 the balancer or lever arm and may be ad- 

 justed by the movable weight P so that 

 the slightest pressure at M at once con- 

 nects the metai J with the two poles 

 K and L, thus closing the electric circuit. 

 F The camera is 



placed upon a 

 board which car- 

 ries the electro- 

 magnets. One pole 

 of the electro-mag- 

 net is connected 

 with pole Q of the 

 box, while the 

 other is connected 

 with one pole of 

 the battery. The 

 other pole of the battery is connected 

 with pole R of the box. When the twig 

 M is pressed down, the metal strip J 

 makes a contact with both poles. The 

 electro - magnet becomes magnetized, 

 draws the iron core and releases the 

 shutter. Since the graflex has a push 

 button to release the shutter, an angle 

 iron is taken; a knob is placed at one ex- 

 tremity and adjusted so as to come into 

 contact with the button. The other ex- 

 tremity carries a weight which alm.ost 

 counterbalances the resistance ol the 

 shutter. A slight downward pressure will 

 now release the 

 shutter. This pres- 

 sure is supplied by 

 the magnet. For 

 operation of a 

 shutter situated 

 in back of the lens 

 see Popular 

 Science Month- 

 ly, June 1917. 



The camera is 

 focused upon atwig 

 or other object 

 placed upon the arm E. The instant a 

 bird hops upon the twig, current flows, 

 the magnet is charged, and draws the 

 angle iron downward, releasing the shut- 

 ter. Thus the picture is taken. It will 

 be found of great advantage to introduce 

 a bell into the circuit so that it \\ ill in- 

 stantly ring when a contact is made and 

 a picture secured, thus enabling the 

 camera to be immediately brought in. 



