English Universal Compound Microscope, c. 1760

Probably Benjamin Martin, London, with later (?) engraving "Dolland" (sic), original lacquered brass, folding tripod, single-sided plano mirror fitted on the front leg, baluster-shaped pillar with rectangular pillar on top, short extension for the attachment of the optical tube via a knob, stage with large central opening, smaller opening at one side, keyhole slot and further opening at front, course focusing by loosening the winged set-screw and sliding the stage up and down, with 6 graduation numbers on the pillar, thumbscrew-adjusted Hevelius-type fine focusing, accessories including: Bonanni spring-stage, live-box, fish-plate, Lieberkuhn, opaque disk fitting into the smaller stage hole, forceps, brass slider, three bone sliders and six objective lenses, in fitted black sharkskin-covered wood case with brown velvet lining and seal 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)