10 
METEOROLOGY OF 1 897. 
§14. Figure 5 shows the self-recording barometer which 
has furnish<^cJ records since 1887. I'his is one of the instru- 
ments of Richard Bros., of Paris It consists of a series, 
eight in number, of hollow corrugated disks, the lov.er one 
fastened to the base of the instrument, the upper one to a 
lever connected with a pen. As the pressure increases, 
these disks are pressed together, and when the pressure 
decreases, expand, and thus, through a series of levers 
cause the pen to rise or fall. I'he instrument as a whole is 
a very satisfactory one. I'he instrument is supposed to be 
compensated for the effect of temperature by a little air 
left inside the disk. As a matter of fact the correction for 
temperature is incomplete, and varying i-emperature affects 
the indication of the instrument. 
THE STATOSCOPE. 
§15. I'he statoscope is essentially a magnifying baro- 
graph on the same principle as the one already described. 
It consists of one large, hollow disk which is connected with 
the exterior air through a tube closed by a stop-cock. In 
using this instrument, the pressures inside and outside the 
disk are equalized by opening the stop-cock. After closing 
the stop cock the inside pressure remains as it was, and if 
the pressure outside increases the disk is compressed; if it 
diminishes, then the elasticity of the box causes the sides to 
expand. The disk is connected with the pen by levers, so 
that the pen rises or falls correspondingly. With change in 
temperature the pressure of the air in the disk alters, and 
the pen will rise or fall whether the outside pressure 
changes or not. A rise in temperature of the inclosed air 
gives an increased pressure in the disk, having the same 
effect on the pen as a decrease in pressure of the surround- 
ing atmosphere. If the temperature lowers, then the inside 
pressure diminishes, or the effect on the instrument will be 
the same as an increase in the {pressure of the outer atmos- 
phere, and the pen will rise, d he clock work makes one 
revolution in 52 minutes. During settled weather, or when 
there is little wind, this instrument shows that the pressure 
of the air changes steadily but without sudden fluctuations. 
In the case of heavy winds the lluctuations are very violent, 
as are shown in the diagrams here given. 
