18 MODERN SEISMOLOGY 
Two light arms engage with points on the top of the mass 
so as to give the components of motion in the horizontal direc- 
tion. These two arms are connected up to the writing points 
by means of a system of similar multiplying levers. We must 
refer to the “Phys. Zeit.,” p. 821, 1903, for full details as to 
these. It must suffice here to say that connexions are pro- 
vided by steel points working in agate cups while axes of rota- 
tion of levers are provided by small Cardan springs which also 
provide the small controlling force required to make the 
pendulum stable. Air-damping boxes are also attached so as 
to provide any required degree of damping. The registration 
is made on smoked paper in a manner clearly indicated in the 
photograph, the writing point being a glass style with a small 
ball point. 
The whole arrangement is of great delicacy and requires 
very careful handling so as to avoid damage to any part. 
The speed of registration is about 10 mm. per minute, 
and automatic time marks are put on the record every minute 
from a good pendulum clock which operates an electrical ar- 
rangement for lightly raising the writing points and then 
lowering them, so that a small break occurs on the trace. 
The dimensions of the enclosing case are 186 cm. high, 138 
cm. broad, and 176 cm. long. It is unfortunately true that 
in this seismograph the two components are not independent. 
The Galitzin Seismographs are made by Mr. Massing, 
mechanic in the Imperial Academy of Sciences, St, Petersburg. 
I am indebted to His Excellency Prince Galitzin for permis- 
sion to use the photographs, Plates 3 and 4. 
Plate 3 shows the horizontal component seismograph 
with galvanometer and recording drum. The general dimen- 
sions of the seismograph may be judged from the fact that the 
casing is about I m. high and rather less than 1 m. diameter. 
The base is a substantial iron casting supported on three 
strong levelling screws. Bolted to this is a rigid iron frame- 
work which carries the horse-shoe magnets and clamps for the 
supporting wires. 
The pendulum which is of Zollner type consists of a strong 
brass rod to which is rigidly keyed the stationary mass of 7 kg. 
