File ALL/01/005 - Gravity Escapement: correspondence, notes and photographs

Includes blueprint of gravity escapements; booklet of lesson 2/12 of British Horological Institute's "Correspondence Course in Technical Horology"; ball and roller bearings metric conversion tables; notes; correspondence regarding the manufacture of wheels and pinions; The Horological Journal article on "A Criticism of the ... Gravity Escapement" by O.B. Hutchinson; 1917 letter from A. Bertlain [?] with a design for a three-legged Grimthorpe escapement; five photographs; and a bundle of correspondence and photographs relating to the regulator clock by Isaac Jackson (1796–1862).