This oldie is embossed around the top rim: Patent/ Spratt// 1850. The patent referred to is this early one by James Spratt: http://reference.insulators.info/patents/detail/?patent=7076&type=U The embossed letters are serif style. The glass is aqua, perhaps a little more green than the photo shows. The '1850' is read from top downwards. That embossing is on the flat face of the tab. It has some nice olive streaks in the back. Unknown previous ownership. A little over 1 3/4" tall and 1 9/16" across the base.