An Indoor Military Riding School With an Instructor Teaching Recruits to Trot; Charles Samuel Keene; 1823-1891; British; undated; Pen; in brown ink: on medium; smooth; beige; wove paper; mounted on very thick; smooth; cream; wove card paper; Sheet: 7 15/16 x 12 3/8 inches (20.2 x 31.4 cm) and Mount: 12 x 17 13/16 inches (30.5 x 45.2 cm); figure study; horseback riders; horseback riding; horses (animals); instructors; military art; recruits; riding school; trotting