Heating and ventilating buildings : a manual for heating engineers and architects . Fig. io.—Birams Portable Anemometer. ence of pressure. The anemometer which is ordinarily em-ployed for this purpose con-sists of a series of flat vanesattached to an axis and aseries of dials. The revolu-tion of the axis causes mo-tion of the hands in pro-portion to the velocity ofthe air. In the forms shownin Figs. 10 and 11 the dialmechanism can be started orstopped by a trip arrangedconveniently to the some instances the dialmechanism is operated by anelectric current, in which case Fig. ii.—Por
Heating and ventilating buildings : a manual for heating engineers and architects . Fig. io.—Birams Portable Anemometer. ence of pressure. The anemometer which is ordinarily em-ployed for this purpose con-sists of a series of flat vanesattached to an axis and aseries of dials. The revolu-tion of the axis causes mo-tion of the hands in pro-portion to the velocity ofthe air. In the forms shownin Figs. 10 and 11 the dialmechanism can be started orstopped by a trip arrangedconveniently to the some instances the dialmechanism is operated by anelectric current, in which case Fig. ii.—Portable PRINCIPLES OF VENTILATION. 4* it can be located at a distance from the vanes. For measuringthe velocity of the wind an anemometer, which consists ofhemispherical cups mounted on a vertical axis, is much was shown by Mr. Combes in 1838 that if n be the num-ber of turns of the vane wheel and a and b constants, thevelocity of the air would be expressed by the formula V = a + pressure on any confined fluid can be expressed in anyunits desired, as pounds or ounces per square inch, or in termsof the height of a column of the same fluid which would givean equivalent pressure, and which is termed the head. Whenmotion takes place, a portion termed the velocity head is trans-formed into velocity, while another portion, termed the pres-sure head, acts to produce pressure. The pressure head can be measured by a simple manom-eter arranged as shown at A, Fig. 12, which in this case con-sists of a U-shaped tube with oneside or leg open and the other con-nected to a tube 71 opening at
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyo, bookyear1910
