Kew Pattern Hygrometer

This is a high quality hygrometer using accurate stem-divided, mercury-filled thermometers which are made with consideration to BMO patterns. The thermometers are fitted to laminated plastic mounts which have been engraved with thermometer divisions. The mounts themselves are then fitted onto a laminated plastic back-plate, moulded from high strength, ‘warp-resistant’ plastic.

A metal bracket attached to the back plate, supports the water reservoir from which a cotton wick runs and is threaded around a circle of muslin covering the bulb of one of the thermometers. The bulb is kept constantly wet by capillary action.

Simple Pattern Hygrometer

This instrument is based upon the design of the Kew Pattern Hygrometer but does not have the laminated plastic back-plate. The thermometers, mounts, water reservoir, accuracy and principles of operation are the same.

Sheathed Pattern Hygrometer

This instrument consists of two sheathed thermometers, manufactured to BS 692, together with supporting brackets and an arrangement of water reservoir, wick and muslin to keep one bulb constantly wet. The inner divided tube is supported in its sheath by a rubber ring at the top and by fusing the two together between the bulb and the lowest graduation.

Whirling Hygrometer

This instrument provides a simple and effective way to measure relative humidity in air. The wet and dry bulb thermometers are held in a slotted frame which is whirled at speed around the handle to give a high and reasonably constant rate of air flow.