Note 28 — Chapter III
Reading edition
Messrs. Baker and Swift have constructed lamps with removal and fixed achromatic bull’s-eye lenses in gymbal, and changeable tinted glass screens. Either of these will add to the usefulness of the lamp in bacteriological research work. Baker’s is constructed on the Herschel doublet formula, and should therefore be free from aberration. It is mounted on a heavy brass tripod foot, has vertical and horizontal movements by rack and pinion, brass reservoir, with screw opening for filling, metal chimney to take 3 × 1½-inch glass slip, removable frame for carrying tinted glass screens, &c.