[Holograph letter, 1822 Feb 13, Killingworth Colliery to Mr. Brewin, Halesowen / R.S. (i.e. Robert Stephenson), giving 'the velocities at which my Father recommends his Locomotive Engines to move' with 12 waggons, each carrying 3 tons. He also gives details of loads on gradients, and of rails. 2p. on 2 leaves. On SM negs. 487-8/89]