An early type of deflexion anemometer is the swinging-plate instrument, now rarely used. It consists of a vertical plate, suspended on knife edges, which deflects under the action of an air current to such an angle that the restoring torque due to the weight of the plate is equal to the air torque.  The angle of inclination may therefore be taken as a measure of the air speed. In modern types such as the velometer and similar German instruments the plate is replaced by a small vane under spring instead of gravity control, which carries a pointer moving over a scale of air speed. Yet again, the plate may be mounted on a torsion wire passing through an asymmetric vertical or horizontal axis, and there will be a relation between the air speed and the amount of twist of the wire necessary to hold the plate in normal presentation to the current. An anemometer of this kind was designed for low speed by J.P. Rees. It indicated air speeds ranging from 0.05 to 1 m/sec.

一种早期的偏转型风速计是摆动片式仪器，现在已很少使用。它是由一块垂直片悬挂在刀口支承上构成的。该片在气流的作用下发生偏转，其偏角的大小正好使该片重量产生的恢复力矩同气流的力矩相等。因此，这一偏转角即可作为衡量空气速度的尺度。在现代类型的仪器中，例如在速度计和类似的德国仪表中，这种摆动片已用一小叶轮代替，叶轮利用弹簧控制而不用重力控制。叶轮上装有一指针，可在标示有气流速度的刻度盘范围内移动。再有，可以把摆动片装在一根通过小片的一条不对称竖轴或横轴的扭丝上。在这种情况下，气流速度与扭丝为使摆动片同气流保持正常位置关系所要产生的扭转量之间存在某种关系。J.P.Rees曾经设计出一台这种类型的风速计，用来测定低气流速度。它测定出从0.05~1米/秒范围内的气流速度。

An example of another type of anemometer in which the airstream displaces an indicator giving an instantaneous reading of velocity or flowrate is the rotameter.  The air flows upwards through a tapered vertical tube in which a float rises until its weight is balanced by the difference of pressure above and below it caused by the motion by the air through the restricted passage around the float.

另一类流速计的典型代表是转子流速计（或流量计）。这种仪器的工作原理是气流使一指针偏转，指示出瞬时速度值（或流量值）。空气向上流过一竖直锥形管，于是管中的浮子（浮球）向上升起，这时在浮子四周狭窄的通道内流过的空气在浮子上下形成压差，当浮子的重量与压差平衡时，浮子即停止上升。

Electrical or hot-wire anemometers are not extensively used in industrial situations, although certain types have been developed for this purpose. The chief limitation on their use is probably the more elaborate apparatus and manipulation that they require. As laboratory instruments, they may be made to give excellent results; and they are particularly well suited to the measurement of low air speeds, a purpose for which they may be designed to have a considerably more open scale than is possible with pressure-tube anemometers.  The hot-wire anemometer is essential for turbulence measurements, but this field is not discussed in this book.

电风速计也即热线风速计，在工业上应用不太广泛，尽管已为此研制过好几种。这类风速计要求更复杂的装置和精心操作，这大概是使它们得不到广泛应用的主要原因。作为实验室用的测试仪器，这类风速计可制作得很精确。而且，它们待别适合于测定低气流速度。为此，可将其设计成分度（刻度）比粥压管型风速计宽得多的形式。热线风速计对湍流测量是必不可少的。但这一领域的问题本书不予讨论。