THE WORLD'S ADVANCE 



371 



into the rabbet and fastened with small 

 nails. 



The back of the frame can be made 

 dustproof.by covering it with a strong 

 piece of paper which should be cut about 

 half an inch shorter and narrower than 

 the extreme outside dimensions of the 

 frame. After sponging it until it has be- 

 come well dampened, spread cold glue 

 evenly, but not thickly, for at least half 

 an inch around its edges on one side. Its 



glued side should be laid upon the frame 

 and rubbed or pressed with a case knife 

 until it adheres closely. It will not be 

 necessary to work all of the wrinkles out 

 of the paper, for when it dries it will 

 shrink and become tight and smooth. 



The screw eyes by which the picture 

 is to be hung should be placed one or two 

 inches above the center of the frame so 

 that its lower part will be the heavier 

 and the frame will hang properly. 



A SELF- WINDING ELECTRIC CLOCK. 



AN electric clock is being sold in 

 France which will run for a length 

 of time determined by the life of the 

 battery usually from one to three years 

 without attention. The winding mech- 

 anism is so simple that it could be made 

 by any amateur electrician. The clock 

 movement is the same as that of any 

 clock, so that the winding mechanism 

 can be attached to any time piece. 



Referring to the accompanying dia- 

 gram, the armature C (the size of which 

 varies according to the size of the move- 

 ment) is placed between the two poles 

 of a permanent magnet. The axis of this 

 armature is terminated by an endless 

 screw driving an ebonite wheel, A, which 

 actuates a second larger wheel, B, rota- 

 ting upon an axis which also carries the 

 square spring shaft. The armature is 

 placed in the circuit of a dry cell of suit- 

 able size, having its terminals connected 

 to two metallic brush-carriers, P and N. 

 The positive connection runs direct to 

 the brush, but the negative connects 

 with a wheel G of insulating material, 

 upon one-half of the circumference of 

 which is fastened the strip of silver plate 

 E. The movements of this whef 1 ! are 

 controlled by a finger H, causing a 

 rotation of G sufficient to bring the strip 

 E in contact with the spring of N. This 

 finger is attached to the axis of one of 

 the movement wheels which makes one 

 revolution every two and one-half hours. 



During its rotation it comes in contact 

 with another finger, K, which turns the 

 wheel G an amount sufficient to close the 



Goffery 



Diagram of the Working Parts of an Electric Clock 

 that will Run for Three Years without Attention. 



circuit. As soon as the motor turns, the 

 wheel B also turns and continues until 

 the pin L raises the arm M of the wheel 

 G, and so breaks the circuit. In two and 

 a half hours the finger H again gives the 

 wheel G a fraction of a turn and closes 

 the circuit. At this moment the pin L 

 is above M, and consequently the circuit 

 remains closed during the time of one 

 revolution of the wheel B. 



Several of these clocks, according to 

 La Nature, have been placed upon the 

 cars of the Paris street railways, and, not- 

 withstanding the continuous vibration 

 and shock to which they are subjected, 

 have been recording the time faithfully 

 for a considerable period without any at 

 tention whatever. J. H. BLAKEY. 



