216 
The mirror gives a full excursion at a current, obtained from an 
accumulator (I) (see fig. 4) and diminished by a resistance (II) of 
several hundreds of Ohms. The intensity of the current is about 
1 milliampère. This eurrent, which affects the galvanometer (III) 
(rnnennenemenmanmnenvenenennsensen: ) closes a second circuit (----— ) 
derived from the same accu. This circuit passes through a second 
relais (IV). There a third cireuit (-—-—----—.-—---—- —) is closed. The 
current for this circuit (and for others, that will be mentioned below) 
is derived from the central-net. The voltage (220 volts direct current) 
is diminished by resistance-lamps. These lamps pass + 0,6 amp. 
This current has three things to do: 
First. It affects a third relais (V) which closes the circuit 
(Heat eeeteee eset) activating the auxanometer-magnet (ME). In this 
way, the contact-device is raised. 
Second. When the platinum-tips of the galvanometer penetrate 
into the mercury, a rather large power is required to turn the mirror 
back, as the surface-tension of the mercury is considerable. The 
terrestrial magnetism doesn’t generate enough power, to warrant 
this safely. Therefore two little magnets (MI) have been placed 
perpendiculary to the iron rod (31). When the current affects these 
magnets, the electrode will be pulled energetically out from the 
mercury; the swinging movement is to be damped by strips of 
. paper, glued on the magnet-piths. 
Third. It has to activate magnet (MID) of a turn-over switch (VII) 
which is an essential part of the: 
Reeording-Apparatus (see fig. 4 and 5). By means of a simple 
clockwork the pen, mounted on a carriage-frame (84), is drawn 
along the paper. Two electro-magnets (MY and MY!) regulate this 
movement. The carriage (84) is connected, by means of silk-threads, 
at one end with a wooden cylinder (83), at the other end with a 
weight (85). The cylinder (83) is mounted on the same axis as the 
cogwheel (36), which turns to the right, when the metal device 
(37), with a pawl (88), moves down. . 
Every second a circuit (sseessssesesseseessseees) iS closed by a- 
second-pendulum (LX) which affects a relais (VI). This relais activates 
by circuit (-+-+-+-+-+-4+-+-+-4-) magnet (MY) which attracts the 
device (37) as its armature (40) is mounted on this device. 
With device (37) pawl (38) is pulled down and the latter involves 
cogwheel (86) in its movement; i.e. cogwheel (86) is turned one 
tooth and cylinder (83) winds up the silk-thread; the carriage (84) 
advances 1 m.M. A spiral-spring (42) pulls back the device (37) 
till it is arrested by a metal block (48), just when pawl (88) catches 
