56 NBGRETTI AND ZAMBEA, HOLBOEN YIADUCT, E.G., 



Fixed at the back of the clock dial, near its outer edge, are two little glass 

 cups containing mercury, one of which is connected to the metal work of the 

 clock ; the other glass cup is connected to the thirteenth terminal on the back 

 of the clock. Immediately over these two cups, and fixed to an arm or lever, is 

 a forked piece of platina wire, which, when depressed into the cups, forms a 

 connecting bridge from one to the other. The lever is depressed when one end 

 is lifted by the minute hand of the clock. This is accomplished by means of a 

 wedge-shaped piece of steel brought through to the front of the dial, and acted 

 upon by the minute hand directly over twelve o'clock ; when the minute hand 

 approaches twelve, it presses the left angle of the wedge and lifts it. 



A terminal at the outside of a box containing twelve magnets is connected 

 to a metal bar running the entire length of the same, to which is attached one 

 end of a wire from each of the twelve electro-magnets ; the other ends of the 

 wires from the electro-magnets are separately connected to the twelve terminals 

 under the box containing the magnets, thence by separate wires to the twelve 

 terminals on the clock, in the order of from 1 to 12 as marked. 



We will now suppose the time to be six o'clock. The battery is connected 

 as follows : One pole to the thirteenth terminal on the clock, the other pole to 

 the terminal at end of box on the Recording apparatus. The electric circuit is 

 now complete. From the battery to the thirteenth terminal on clock, then to 

 one of the glass cups, over the little bridge of wire to the other glass cup, thence 

 through metal work of the clock to the spring, which spring touches upon the 

 stud at the back of the hour hand (at, say six o'clock), from thence to No. 6 

 terminal on the back of the clock, from there to No. 6 terminal under the 

 box containing the electro-magnets, through No. 6 magnet to the bar above, 

 then to the terminal at the end of the box, and back to battery. In its circuit, 

 No. 6, magnet attracts its keeper, the catch falls, and allows No. 6 thermometer 

 to turn over, and in like manner throughout the series. 



Price, fig 64. 52 10 



NEGRETTI AND ZAMBRA'S SUNSHINE RECORDER. 



75. This instrument shown by fig. 65 consists of a glass sphere ground 

 perfectly true, mounted upon a brass frame, with suitable adjustments for placing 

 its axis parallel with the axis of the earth ; it has also a divided semi-circle 

 arranged to adjust the apparatus for use in any latitude. 



Surrounding one-half of the glass sphere is placed a concentric metal plate, 

 for holding the prepared and divided paper cards, upon which the record is 

 burned by the concentrated Solar rays. 



