For air, each bottle had tiny pinholes in its lid.

Opening N. hole, foramen; puncture, perforation; fontanel^; transforation^; pinhole, keyhole, loophole, porthole, peephole, mousehole, pigeonhole; eye of a needle; eyelet; slot.

Then, by a simple contrivance, I make two pinholes in each of them, to enable me to hang them up one in front of the other, like a pack of cards, upon the same pair of pins, in such a way that the eyes of all the portraits shall be as nearly as possible superimposed; in which case the remainder of the features will also be superimposed nearly enough.

These pinholes correspond to what are technically known to printers as "register marks."

The load was applied by rods passing through the pinholes in the arms.

The lower ends of these rods were attached to a system of equalizing levers, so arranged that the load at each pinhole would be the same.

We halted, peering at the glow that now sprinkled out through many a pinhole aperture in a fairy lattice of pine needles.