Chair back cushions are buffeted by every wind that blows, and periodic summer rains run from the top of the cushion down, creating a greater opportunity for taking on moisture through the seams, with the resulting risk of mold and mildew.
Numerous attempts have been made to find periodic variations in thunderstorm frequency.
His name is best known for the share he had in the periodic classification of the elements.
In its chemical relations, titanium is generally tetravalent, and occurs in the same sub-group of the periodic classification as zirconium, cerium and thorium.
"Time for our periodic chat, little brother," he said, and motioned to the other chair before the hearth.
In spite, however, of all that has been done, the Elbe remains subject to serious inundations at periodic intervals.
In any case, the alterations in level appear to be merely periodic, and due to fluctuations in rainfall, and do not point, as some have supposed, to a secular drying up of the lake.
Instead they searched their surroundings wildly in the light of periodic lightning and the fire at the far end of the hall.
This periodic distribution in time and space constitutes an electric wave proceeding outwards in all directions from the sending antenna.
This is defined as the speed of revolution of the fictitious body already described, revolving with a uniform angular motion and the same periodic time as the planet.