The plate speeds are shown as 'times wet-plate' 30x was given as the average speed for ordinary plates and 60x for rapid plates. Two ranges of f numbers are shown - continental and British. The faster apertures shown and also the faster shutter speeds are hopeful for the period. In use a slide carrying the plate speed is set against the subject, the lower slide index is set against the light intensity (time of year and day). The shutter speed and aperture pairs can then be read.

The meter was still listed in 1910 by W.H. Phillips & Son, the plate speeds then were shown as 1/10 H&D. Different finishes were available at this time: plain boxwood, black-stained boxwood with ivorine slide, ivorine in a leather case and aluminium in a leather case. Prices ranged from 5/3 to 20/6.

In use a table showing time of day, time of year and sky conditions gives an index. The index is set in a window on the front of the card, the shutter speed and aperture pairs can then be read against the type of subject. Only one plate speed is shown.

Cadett were early adopters of H & D speed numbers, an advertisement states they were 'used since commencement' but it is not clear if the speed here is H & D. On the second example Cadett is shown as a limited company.

The meter consists of fixed scales and two moveable scales. In use the time of year and time of day are found in a table which gives a light value (A - J). The sky condition scale is matched against a scale marked A - J. The subject scale is then moved to point to the plate speed. The shutter speed and aperture pairs can then be read. There are also index positions for photographs in moonlight and a separate aperture scale for pinhole stops.

Compiled by the Rev. F.C. Lambert and William Tylar.