Hygiene and public health / by B. Arthur Whitelegge.

  • Arthur Whitelegge
Date:
1894
Catalogue details

Licence: Public Domain Mark

Credit: Hygiene and public health / by B. Arthur Whitelegge. Source: Wellcome Collection.

    50/610 (page 38)
    Hot water may also be used under pressure at temperatures considerably exceeding 212° Fahr., on Perkins' system. Strong half-inch iron pipes are used, and instead of a boiler part of the pipe is carried through the fire. Steam may be used at high or low pressure in like manner. There is a material difference in the result of these various methods of heating, apart from their relation to ventilation. Hot air warms a room by convection only, ordinary open fires or gas-fires almost entirely by radiation; stoves and hot pipes act in both ways, but chiefly by convection. In the one case (radiation) the air remains comparatively cool, if the ventilation is efficient; in the other (convection) the air is hot, and therefore dry, and requires moisture. As will be explained in the next chapter, the dryness of air is merely a relative term ; for example, the amount of moisture required at 52^^ is twice as great as at 32° F. (page 45).