Early English Brass Compound Microscope by Jones, c. 1800

Signed: "W & S Jones 30 Holborn London", folding tripod base, conical pillar capped by a compass joint, short arm carrying the 10 in. limb, front with rack and pinion for coarse focusing to the stage, height-adjustable plano-concave mirror and condenser lens, rectangular mechanical stage with knurled screw adjustments, 6 ½ in. long body tube, overall height 17 ¾ in., with 3 objective lenses, 5 Lieberkuhn reflector lenses, live box, brass revolver with 6 pinhole diaphragms, Bonanni sprung stage, fish plate, bull's-eye condenser, stage forceps, 3 boxwood specimen sliders with opaque objects and compass microscope, in fitted mahogany case, retailer's paper label "J.D. Potter" in lid.

布雷克拍品等级是为了方便竞买人判断拍卖品的成色而设置的。布雷克等级用1到6级来标注外观和功能的成色，(从非常好到非常差)。 在目录图册里用括号里的2个数字来表示，前一个数字表示外观成色的级别，后一个数字表示功能成色的级别。如(3/2)表示外观成色是3(满意的)，功能成色2(好)。 成色 定义参照下列标准： 1 - 非常好 (未使用过，没有使用痕迹) 2 - 好 (新，极少的使用痕迹) 3 - 满意的 (普通的使用痕迹) 4 - 及格的 (明显的使用痕迹，某个非主要部件是后配的) 5 - 有缺陷的 (极明显的使用痕迹, 某个主要部件是后配的，功能上有缺陷，需要修理) 6 - 非常差 (严重破损, 缺少重要部件)