air pressuren.

1660 R. Boyle New Exper. Physico-mechanicall Summary, p. vi The 28 Experiment, touching the sudden eruption of Bubbles from the water, when the airs pressure was speedily remov'd.

1729 S. Switzer Introd. Gen. Syst. Hydrostaticks & Hydraulicks I. xiv. 195 The Mercury by the Air's Pressure is sustain'd at the Height f in the Tube.]

1837 Edinb. New Philos. Jrnl. 23 304 I have been exposed in a diving-bell in England to an air-pressure of forty-five inches, for almost an hour together.

a1875 E. H. Knight Pract. Dict. Mech. I. 50/2 Gruber's air-pressure filter.

1910 R. Cobleigh Handy Farm Devices 78 This pressure tank is so arranged that by pumping it full under strong air pressure the water is forced all over the house.

1946 Nature 9 Nov. 674/2 Using air-flow through a capillary to regulate the air-pressure difference.

1997 P. Pullman Subtle Knife (1998) xiv. 299 In a storm, when the air pressure sank, you had to offset that drop against the altimetric reading, and very often it was a crude rule-of-thumb calculation.

2003 O. Shine Lang. Tennis 92 Long-lasting tennis balls which do not rely on air pressure to provide their bounce.