PT - JOURNAL ARTICLE ED - , TI - The National Physical Laboratory AID - 10.1136/bjo.10.8.441 DP - 1926 Aug 01 TA - British Journal of Ophthalmology PG - 441--442 VI - 10 IP - 8 4099 - http://bjo.bmj.com/content/10/8/441.short 4100 - http://bjo.bmj.com/content/10/8/441.full SO - Br J Ophthalmol1926 Aug 01; 10