flatus, in the military art, a sudden com- pression of the air caused by the discharge of the bullet out of a great gun. The blast sometimes throws down part of the embrasures of the wall.

Blast is also applied in a more general sense to any forcible stream of wind or air, excited by the mouth, bellows, or the air.

Blast is also used in agriculture and gardening, for what is otherwise called a blight.

Blasts or blattings are by some supposed owing to cold; by others to the want of a due supply of sap; by others to ascending fumes of the earth; by others to sharp winds and frosts, immediately succeeding rains. That species called uredines or fire-blasts, is supposed by Mr Hales owing to the solar rays reflected from or condensed in the clouds, or even collected by the dense steams in hop-gardens and other places. The effect of them is to wither, shrivel, scorch, turn black, and as it were burn up the leaves, blossoms, and fruits of trees, shrubs, herbs, grafts, corn, even for whole tracts of ground.

Physicians also speak of a kind of blasts affecting hu- man bodies, and causing erysipelas, pallsies, &c.

Blasts, among miners. See DAMPS.