Never could Starbuck forget the old man's aspect, when one night going down into the cabin to mark how the barometer stood, he saw him with closed eyes sitting straight in his floor-screwed chair; the rain and half-melted sleet of the storm from which he had some time before emerged, still slowly dripping from the unremoved hat and coat.
Taking the range of the barometer in Great Britain from 28 to 31 in., giving a difference of 3 in.
In cases where the density of the air is not of average value, as on a high mountain, or with an exceptionally low barometer for example, an allowance must be made.
The invention of the barometer and Torricelli's explanation of the vacuity above the mercury column placed before the members of the Florentine academy a ready method of obtaining vacua; for to exhaust a vessel it was only necessary to join, by means of a tube provided with stopcocks, the vessel to a barometer tube, fill the compound vessel with mercury and then to invert it in a basin containing this liquid, whereupon the mercury column fell, leaving a Torricellian vacuum in the vessel, which could be removed after shutting off the stop-cocks.
The idea of the pressure of the air and the invention of the instrument for measuring it were both new when he made his famous experiment, showing that the height of the mercury column in a barometer decreases when it is carried upwards through the atmosphere.
Sir Isaac Newton devoted the 31st query in the last edition of his Opticks to molecular forces, and instanced several examples of the cohesion of liquids, such as the suspension of mercury in a barometer tube at more than double the height at which it usually stands.
The substance is weighed into a small stoppered bottle, which is then placed beneath the mouth of the barometer tube.
Farr used to call the latter the barometer of the former.
And the weight of air displaced depends upon the density of the air at the time of weighing, and therefore the barometer reading must be taken.
In the monsoon region, where the barometer rises o 38 in.