黑便士邮票“彩虹试验”

3-stamp trial plate, 1840
A mauve-pink printing from the “rainbow trials” of alternative stamp colors, using a special plate of three stamps.

3-stamp trial plate, 1840, mauve-pink

3-stamp trial plate, 1840, lilac-brown

12-stamp trial plate, May 1840, full corners, black

12-stamp trial plate, May 1840, blank corners, black

12-stamp trial plate, May 1840, orange-red

12-stamp trial plate, May 1840, dark brown

12-stamp trial plate, June 1840, paper dipped in potassium ferrocyanide, black

12-stamp trial plate, June 1840, paper dipped in potassium ferrocyanide, red-brown

12-stamp trial plate, June 1840, tête-bêche, pink

Single trial impressions

Single trial impressions, submitted to Rowland Hill August 31, 1840

Trial impressions annotated by Joshua Bacon, September 3, 1840

Color selection, red, sent by Rowland Hill to Chancellor of the Exchequer, September 1, 1840

Color selection, blue, sent by Rowland Hill to Chancellor of the Exchequer, September 1, 1840