The 1886 patent date on the bottle base

Close view of the embossed underside of an amber glass bottle base, showing raised lettering and digits around a circular panel with a number in the middle — Click to view full size

The embossed ring on the underside of the base, photographed square on. Read round the ring it gives PAT^D AUG 24 1886, with the mould number 19 in the centre.

The lettering is shallow and the glass is dark, so no single angle shows all of it. This frame was lit and cropped to bring up the ring; the day of the month was read by turning the image a quadrant at a time, and the reading is set out in full on the record for the base itself.