PRESENT STATE OF OUR KNOWLEDGE OF THE UPPER ATMOSPHERE. 81 
- mometer consists of two annular Bourdon tubes of very thin steel 
filled with alcohol, and the hygrometer consists of two bundles of 
hairs. The anemometer originally used was a small instrument of the 
Robinson cup pattern operating through an electro-magnet on a small 
hammer and recording on the drum in steps, each step corresponding to 
2°8 km. of wind. The anemometer cups were originally fixed to the upper 
end of the kite, but later were placed on a vertical spindle above the hinder 
end of the vane, so as to be away from the disturbing influence of the 
_ remainder of the apparatus. The thermometer tubes and hygrometer 
hairs are enclosed in a polished tube open at both ends, which is kept 
always end on to the wind by means of the vane. The rest of the instru- 
ment is enclosed in a light protecting case. In later patterns of the instru- 
ment used at the Lindenberg Observatory, Germany, the anemometer 
was replaced by an Assmann anemometer. As the Robinson cups were 
very liable to damage in falling, Assmann’s instrument was designed on 
the Woltmann flywheel anemometer principle. It took the form of an 
eight-bladed fan fitting into the end of the aspiration tube and operating 
through a train of cogwheels on the marking pen. The instrument, when 
used with the anemometer, is suspended from the wire some distance 
below the kite, to avoid any disturbing effect due to the latter. The 
weight of the instrument is about 1:06 kgm. 
The Bosch-Hergesell kite meteorograph differs in having a Bourdon 
tube barometer and an annular Bourdon tube filled with alcohol for ther- 
_ mometer. The anemometer is of the Robinson type, operating through a 
_ train of cogwheels and pressing the style on the record sheet once per 
_ minute in a wind of 6 m.p.s.—i.e., one contact per 360 metres of wind. 
_ The thermometer and hygrometer are enclosed in an aspiration tube, 
_ and the anemometer cups are mounted on a vertical spindle’ projecting 
_ through the instrument case. The protecting case is of aluminium and 
the frame of the instrument of magnalium. The total weight is 750 gm. 
The Dines instrument is of quite different design.!_ The frame consists 
of a wooden tray with raised sides for protecting the instrument from 
injury. In the middle of the frame a flat circular disc of white cardboard 
is caused to rotate by a small clock. The separate parts are mounted 
on the wooden frame and register through pen levers by means of special 
ink on the cardboard disc. The pressure and humidity are recorded side 
by side on one half of the disc and the temperature and wind velocity 
diametrically opposite on the other half of the disc. The barometer con- 
sists of a single aneroid, to the centre of which is soldered a projecting 
‘piece, which operates directly on the short arm of the pen lever. The 
thermometer consists of a long spiral copper tube filled with alcohol, and 
carrying at one end a small thin-walled box similar in shape to an aneroid 
box. The tube is fixed to the under side of the frame, but the box projects 
through to the upper side. A projecting piece soldered to the middle of 
the free side of the box operates directly on the short arm of the pen lever. 
The hygrometer consists of a bundle of hairs enclosed in a ventilation tube 
situated in the under side of the frame, and the movement is transmitted 
to the pen by levers fixed to a spindle passing through the frame. The 
 anemometer is actuated by the pressure of the wind on one or several light 
Spherical balls suspended by about 40 feet of thread attached to the end 
_ of a lever pivoted on the instrument frame. The pull is balanced by 
a spiral spring, so arranged that the deflection of the recording pen 18 
_ proportional to the wind velocity. 
} Symons, Met. May., vol, xxxix, 1904, p, 109. 
1909. G 
