The Rotating-Top Inkstand: Turn the Lid and the Pen Holes Shut

"C, C, is the rotating top. These tops, as represented, have two holes for the inserting of pens into the ink; a, a, are the holes through the rotary top, and b, b, those through the permanent top, which in the section are shown as coinciding." "D, is a spring handle, made of wire, by which the ink-holder may be lifted; but its main purpose is to keep the rotating top in place, and to allow of its removal when the ink-holder is to be cleaned, or a fresh supply of ink is required."

**Fixed top.** Unscrew the lid of a glass jar. Drill two 6 mm holes through it opposite each other, 12 mm from the centre, and a 5 mm hole in the centre. **Rotating top.** Cut a disc from aluminium sheet the size of the lid's top. Drill matching 6 mm holes and a 5 mm centre hole. Put an M5 bolt through both centres with a washer and nut, snug enough that the disc turns but stays where it is set. Bend a wire handle and hook its ends under the lid's rim. **Wiper.** Glue a scrap of sponge to the lid's edge for wiping the pen. **Test.** Fill two jars to the same level with ink and fit them with tops: shut one by turning past the notebook's angle, and leave the other with its holes aligned. Weigh both every day for a week. Then turn the top in 5° steps with the protractor and look through the holes against a light to check the notebook's open fractions.

**Daniel Harrington** of Philadelphia received US 4,258, dated 8 November 1845 and antedated 2 September 1845. His body could be glass, porcelain or other material, the permanent top was cemented on with resinous cement, a stop pin limited the rotation, and the rotating top lifted off so ink could be poured in through the permanent top's large centre hole. **Honest limits.** A jar lid and an aluminium disc on a bolt stand in for his cemented metal tops. The notebook treats the holes as flat circles; its sizes are examples. Your weighings and light checks are the result.