34 SEVENTH REPORT—1837. 
ing an account of these instruments, together with some tables, founded 
on the records they have furnished. He also presented drawings of 
the Registering Anemometer and Rain-Gauge alluded to. 
The direction of the wind is obtained by means of the vane attached 
to the rod, or rather tube, that carries it, and consequently causes the 
latter to move with itself. At the lower extremity of this tube is a 
small pinion working in a rack, which slides backwards and forwards 
as the wind moves the vane, and to this rack a pencil is attached, which 
marks the direction of the wind on a paper ruled with the cardinal 
points, and so adjusted as to progress at the rate of one inch per hour 
by means of a clock; the force is at the same time ascertained by a 
plate one foot square, placed at right angles to the vane, supported by 
two light bars running on friction rollers, and communicating with a 
spiral spring in such a way that the plate cannot be affected by the 
wind’s pressure without instantly acting on this spring, and communi- 
cating the quantum of its action by a light wire passing down the centre 
of the tube to another pencil below, which thus registers its degree of 
force. The rain is registered at the same time by its weight acting on 
a balance which moves in proportion to the quantity falling, and has 
also a pencil attached to it recording the results. The receiver is so 
arranged as to discharge every quarter of an inch that falls, when the 
pencil again starts at zero. 
Suggestions as to the probable Causes of the Aérial Currents of the 
Temperate Zones. By Mr. Birr. 
Mr. H. W. Dove has lately proposed, Phil. Mag. Sept. 1837, a Theory 
to account for the variations in the direction of the winds, on the prin- 
ciple that the earth’s rotatory motion produces a change in the direc- 
tion of a stream of air passing over any given place in the temperate 
zones, occasioning a northerly current to become easterly, and a 
southerly one westerly. 
The author presented a diagram of the directions of aérial currents 
observed, and offered suggestions as to the probable causes of the varia- 
tions in these directions. The general tendency of the wind being un- 
derstood to vary in the order of S.E., S., W., N., N.E. during the direct 
periods, and N.E., N., W., S., S.E., during the retrograde, the author 
proposes the following explanation. 
The heated air from the intertropical regions flows over towards the 
poles, giving rise to currents in every possible direction on either side 
of the torrid zone, and as the sun is vertical to a spot which traverses 
a parallel of the torrid zone during twenty-fours, it is evident that the 
currents thus generated are extremely numerous, and situated in every 
possible direction with respect to any given place within the temperate 
zones, London for example; this will be readily apparent upon inspect- 
ing a terrestrial globe, when it will be seen that the spaces some of 
these currents have to traverse previous to their arriving at London are 
of much greater extent than others, and they will consequently arrive 
at the place of observation much later. Now supposing these currents 
