Solar Microscope with Projection Device by Dollond, c. 1790

Signed "Dollond, London, Sold by King & Son Clare St. Bristol", 5 ½-inch square brass plate with rack and pinion and sector to the 10 ½ x 3 ½-inch mirror, conical body tube with 2 ¾-inch diameter lens, drawtube coarse adjustment, Wilson-type microscope with rack-and-pinion fine focusing screwing into body tube, dovetail aperture for the field lenses, total length 22 in; with rare projection attachment for opaque objects, cuboid brass case with adjustable mirror and spring-loaded object holder; in mahogany carrying case with accessories: 3 dovetail field lenses, 2 knurled screws for the plate, brass slide with 6 pinhole diaphragms, 5 bone specimen slides, 3 wood slides with opaque objects, 3 large hardwood specimen slides and 3 pairs of tweezers. Mirror glass cracked, otherwise in good original condition

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)