When the shutters are put up, light filters through the interstices of the boards.

Wave propagation in periodic structures; electric filters & crystal lattices.

Our illustration shows one of Loysel's Hydrostatic Urns, which are admirably adapted for making good and clear coffee, which should be made in the following, manner:Warm the urn with boiling water, remove the lid and movable filter, and place the ground coffee at the bottom of the urn.

Put the movable filter over this, and screw the lid, inverted, tightly on the end of the centre pipe.

To give our readers some general idea of size, weight, and produce of water, we may say that a plain cylindrical distiller, mounted on a square filter case, measuring 3 ft. 9 in.

The Master slid colored ray-filters over his binoculars, to shield his eyes from the direct dazzle of the rising sun, and swept that incandescent arc.

On my next visit, I took a few kilos of gravel, a pump, plastic plants, fish medicine, the undergravel filter, some pipeline, a few regulators, T-joints and a fishnet.

A feeble light filters through the blind of the guard's box.