Uptake

The smoke passage between the smoke box and chimney.

Vacuum Space containing no matter. As used in steam engineering the term is applied to the partial vacuum obtained by abstracting, in a closed vessel, the heat of vaporization from steam, reducing that given volume of steam to an approximately equal weight of water of much less volume. Vacuum is measured by the height of a column of mercury sustained in the long leg of a bent tube, the long leg being connected with the enclosed space in "condenser," the other open to the atmosphere. The sustaining force is the difference between the pressure of the atmosphere and the slight pressure in the "condenser." In case of perfect vacuum this slight pressure would be zero.