Miniature Working Model of a Walking Beam Steam Engine, c. 1850

Marked "W & S Jones, 30 Holborn, London", all-brass machine parts, Watt-type 6-column low-pressure balancing steam engine, vertical cylinder, flywheel Ø 2 ½ in., spirit-heated brass boiler, Ø 1 ¾ in., on base in the style of a factory plant, mahogany plinth, dimensions 7 ¼ x 4 ¾ x 7 4/5 in., complete with burner, untested. – Note: The firm of W. and S. Jones were among the most successful manufacturers of scientific instruments in London in the late 18th and early 19th centuries, selling a wide range of optical, mathematical and philosophical apparatus. It was based at 30 Holborn Street until Samuel Jones' death in 1859.

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)