309,726. Kelvin, Bottomley, & Baird, Ltd., and King, F. A. April 2, 1928. Colours, testing. - Apparatus for testing the effect of light on textile products or half-products such as slubbings, dyes, paints &c., with the object of determining the fastness of colours to light in con. junction with varying degrees of humidity, consists of a number of swatch boxes 1 surrounding a casing 2 containing a source of light. The boxes 1 are mounted to swing on tubular trunnions 9 serving as air conduits by which the air flows from box to box. In each box is a swatch holder consisting of a frame F held in place by a clip f, and each box is provided with a door 21 for changing the materials under test. To permit the continuous passage of moist air past a box which has been turned down for inspection &c., the lower part 4 of the box forming the hinge on the pipe 9 is formed with a by-pass 19 registering with apertures 18 when the part 4 closes the apertures 17 by which the air enters the box. Restoration of the box to the position shown in Fig. 1 causes the air to circulate through the box instead of through the bye-pass 19.