BACK a.
er faces of a wall, or upon the haunches of an arch or vault. -- Back pressure. (Steam Engine) See under Pressure. -- Back rest, a guide attached to the slide rest of a lathe, and placed in contact with the work, to steady it in turning. -- Back slang, a kind of slang in which every word is written or pronounced bac…
BACTERIUM n.
A microscopic vegetable organism, belonging to the class Algæ, usually in the form of a jointed rodlike filament, and found in putrefying organic infusions. Bacteria are destitute of chlorophyll, and are the smallest of microscopic organisms. They are very widely diffused in nature, and multiply with marvelous rapidity…