Older children or adolescents who try to remove earwax themselves with hair pins or similar objects run the risk of perforating the eardrum or damaging the fragile skin covering the ear canal, causing bleeding and the risk of infection.
Over the surface of the plate and between it and the indicator there was passed, at a regularly uniform speed, in a direction perpendicular to the line of motion of the indicator, a material capable of being acted on physically by the sparks, through either their chemical action, their heat, or their perforating force.
+h,r, 1)s~,~s-s Diatoms and Desmids, according to recent researches, the thickenings on the outer walls of the cells are due to the passage of protoplasm from the interior of the cell to the outside, through pores which are found perforating the wall on all sides.
Thus, for instance, to% aluminium bronze is scratched by an ordinary steel knife-blade, yet the sets of needles used for perforating postage stamps last longer if made of aluminium bronze than if made of steel.
Mineral, vegetable and animal substances, by means of tools and apparatus of stone, wood and bone - tools for cutting, or edged tools; tools for abrading and smoothing the surfaces of substances, like planes, rasps and sandpaper; tools for striking, that is, pounding for the sake of pounding, or for crushing and fracturing violently; perforating tools; devices for grasping and holding firmly.