surface de chauffe, heating-surface

5. au fur . . . formation, as rapidly as they are fortned. Fur is an old word meaning "market price," "rate," and is now used only in the combination au fur et à mesure, "in proportion."

6. multi-tubulaires, multitubular, constructed with many tubes.

7. sept atmosphères; the weight or pressure of the atmosphère is about 15 pounds to the square inch, and this is commonly employed as a convenient unit for pressures resulting from other causes, such as the force of steam. So in a steam boiler a pressure of seven atmosphères means about 105 pounds to the square inch.

S. fasse explosion, should explode, burst. The subjunctive is required after a statement of déniai.