北魏（386-534）在公元439年统一北方。前篇博文已说北魏太武帝太延元年(公元435年)的墓穴符合尺长28.0~28.1 cm，《隋书•律历制》“审度”中后魏(即北魏)前尺和中尺皆 28.0 cm；而众多北齐(550-577) 石碑像适用尺长28.1 cm。《中国科学技术史•度量衡卷》所说“从北魏前期的25.6 厘米至后期增加至29.6 厘米”等(P287)不能成立。

下面再以美国 National Museum of Asian Art 藏石像，说明北魏后期及北齐尺长28.1 cm；数据精确到 1/16 inch 或 mm，测算的可靠性没有问题。

 (A)  高七尺欠1.2 cm，宽二尺七欠0.3 cm

Period：515-525, probably 521

Material：Sandstone with traces of polychrome pigment

Dimension: H 195.5 x W 76.2 x D 38.1 cm (76 15/16 x 30 x 15 in)

https://asia.si.edu/explore-art-culture/collections/search/edanmdm:fsg_S1991.157/

 (B)  高三尺七寸欠0.1 cm，宽一尺七寸欠0.4 cm

Period: ca. 523

Geography: Gongxian Cave Temples, Cave 1, Henan province, China

Material: Sandstone with traces of pigment

Dimension (overall): H 104.1 x W 47.4 x D 27.2 cm (41 x 18 11/16 x 10 11/16 in)

https://asia.si.edu/explore-art-culture/collections/search/edanmdm:fsg_F1952.15/

(C)   高二尺五寸欠0.3 cm，宽一尺二寸过0.5 cm；中心高一尺、宽八寸

Period： 521

Material：Sandstone

Dimension：H 70 x W 34.2 cm (27 9/16 x 13 7/16 in)

https://asia.si.edu/explore-art-culture/collections/search/edanmdm:fsg_F1969.5/ 

(D)  高四尺二寸整，宽二尺七寸欠0.2 cm，厚一尺七寸欠0.5 cm

Period: 550-577

Geography: northern Xiangtangshan, North Cave, Hebei province, China

Material: Limestone with traces of gesso and pigment

Dimension: H 118 x W 75.7 x D 47.3 cm (46 7/16 x 29 13/16 x 18 5/8 in)

https://asia.si.edu/explore-art-culture/collections/search/edanmdm:fsg_F1913.57/ 

(E)  高七寸整，宽三尺四寸欠0.2 cm，长六寸欠0.4 cm。 

两端上方高五寸、宽三寸；下方总宽二尺八寸，九人各占三寸，两侧边合宽一寸；圆内径二寸准确。其他尺寸不再细说。

Lateral stretcher from the base of a funerary couch with Sogdian musicians and a dancer

Period: 550-577

Geography: Probably Ce Xian, Henan province, China

Material: Grey marble with traces of pigment

Dimension: H 19.7 x W 95.3 x D 16.5 cm (7 3/4 x 37 1/2 x 6 1/2 in)

https://asia.si.edu/explore-art-culture/collections/search/edanmdm:fsg_F1915.336/ 

形体较小者的尺寸不再解读；所见仅一座石像(链接如下)尺寸不甚规整，原因不明。北魏后期以及北齐使用尺长28.1 cm 完全没有疑问。北周的尺长容另文说明。

https://asia.si.edu/explore-art-culture/collections/search/edanmdm:fsg_F1968.45/

最后介绍的这座北齐(550-577)石像，石灰岩，可能来自河南；形体数据从网页复制

https://asia.si.edu/explore-art-culture/collections/search/edanmdm:fsg_F1923.15/

Dimension: H 151.3 x W 62.9 x D 31.3 cm (59 9/16 x 24 3/4 x 12 5/16 in)

肩高五尺四寸欠 0.4 cm。

下面几张照片为博主2016年8月9日下午所摄 ，七年已经过去了，却恍如昨日。

容我叹息一声而不说话。

注：文中数据以尺长28.1 cm 计算。若以尺长28.0 计算，偏差会减小。不过，成品尺寸略欠属于正常吧。