302 
DR. MEYER WILDERMAN ON CHEMICAL DYNAMICS 
The Galvanometer, dc. (See fig. 7.) 
With an acetylene flame of about 250 candle power it was possible to use a 
Crompton’s dead-beat galvanometer instead of the more sensitive one made by 
Nalder Brothers. 
One of the conducting leads p from the Rubens thermopile leads to the interrupter 
E (see diagram p. 357), the purpose of which is either to interrupt the current, or to 
bring the lead (|i) from the thermopile into connexion with the lead ( p ') conducting 
to the galvanometer (g), or to connect the lead (X) from the nickel-iron thermocouple 
of the quartz vessel with the lead (p') conducting to the galvanometer. From E the 
wire passes to the reversing key, which is enclosed in an asbestos box, and from here 
to the galvanometer (g). 
The spot of light from an electric incandescent lamp, after jiassing through a 
lens, was reflected from the galvanometer mirror upon a transparent celluloid scale. 
Great difficulty was experienced in steadying the galvanometer ; the suspension of 
the galvanometer in a box on an india-rubber band, and the placing of the box on a 
very heavy stone, which again was placed in its turn on thick pieces of india-rubber, 
gave vibrations of 1 to 2 millims., owing to the fact that the dark room the author 
had to use was near machinery at work. It was ultimately steadied in the following 
manner :—A soft thick copper wire was drawn from one wall of the room to the 
other, and the wire was first stretched and shortened until it stood the weight of the 
box containing the galvanometer suspended on two very thick and flexible rubber 
rings. Inside the box the galvanometer (with the wooden plate on which it was 
standing on pieces of copper) was suspended from one rubber ring on the hook 
of a screw, which was passed through a hollow wooden cylinder on the top of 
the wooden box and held by a nut, placed on a metal plate on the top of the 
wooden cylinder. By raising the screw outside and turning the nut the galvano¬ 
meter could be brought to any height desired, and by carefully turning the screw 
it could be placed at any angle, so as to get the spot of light at any required 
place on the scale. The screws of the galvanometer were resting upon metal pieces 
on the wooden plate, and adjusted so as to get the required sensitiveness by 
weakening the magnetic field, i.e., by bringing the circular coil partially out of 
the central iron core. It was further necessary that the whole arrangement of 
the suspension of the galvanometer should not be upset by the necessity of fixing 
the leads to the galvanometer, since it was impossible to ensure that greater 
vibrations of the leads outside the box would never take place. For this reason 
the galvanometer was not connected directly with the heavy leads ; these were 
fixed to the wooden box, then for each lead three or four pieces of very thin 
galvanometer suspension wire (each about 2 inches in length) were soldered to 
two pieces of thick copper wire; one of them was fixed to the lead and the other 
to the terminal of the galvanometer. Thus the galvanometer became for the first 
