English Boxwood Nocturnal, 17th Century

Celestial instrument for displaying the time at night, with a heart-shaped handle stamped "FOR BOTH BEARS", central brass hinge with visor, back with table for measuring latitude by the altitude of the Pole Star, eight-pointed compass rose at the center, date and hour scales on the front of the main body below a rotating disc with an hour scale, a scale for the age of the moon and two shaped hands, one marked ‘GB’ and the other ‘LB’ (for Great and Little Bear), with a rotating index arm at the top, 4 1/10 in. diameter, length 9 ½ in., minor stress split in the main body. – Note: To use the Nocturlabium, the user sets one of the small pointers for the constellation being observed to the corresponding date, looks through the hole in the center at the Pole Star and aligns the long pointer with one of the two stars in the Great or Little Bear that coincide with the Pole Star. The time is indicated by the position of the pointer opposite the hour scale on the rotating disc.

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)