HYGROMETER WHIRLING (LSE) The ventilated type of hygrometer gives grater accuracy for humidity demonstrations and is particularly useful for measuring local differences in humidity. There are two thermometers mounted in metal case, one having a wick dipping into a water reservoir at the end of the frame. The thermometers are stem engraved with lens fronts for easy reading range ?5 to 50?C x 0.5?C Qty :