A. In summer time.
Q. Why does the barometer vary less in summer than in winter time?
A. Because the temperature of our island is so nearly equal to that of the torrid zone, that its state is not much disturbed by interchange of currents.
Q. What effect has wind on the barometer?
A. North and east winds make the mercury rise; all other winds make it sink; but south and west winds make it sink lower than any other winds.
Q. Have heat and cold any effect on the barometer?
A. No, not of themselves; but because cold weather is generally either dry, or rough with north-east winds, therefore the mercury rises in cold weather; and because warm weather is often moist or fanned by south-west winds, therefore, the mercury sinks.
Q. Why is the mercury of a barometer lower in the torrid than in the frigid zones?
A. Because the warm air of the torrid zone contains much more vapour than the condensed air of the frigid zone; and the moister the air, the less is its pressure.