PICKSLAY'S PERUVIAN STEEL SHEFFIELD 19th Century English Oval button Automatic knife

Antique PICKSLAY'S PERUVIAN STEEL SHEFFIELD 19th Century Oval button Automatic lockback knife made in Sheffield England between 1820 and 1832. This oval button, Dagger grind switchblade is nearly 200 years old! Charles Pickslay experimented with alloying steel with silver and other elements in the 1820s and called his invention "Peruvian Steel". 

This knife measures 4 5/16 inches closed and 7 5/16 inches open with Coined brass liners and nickel silver bolsters, oval button & pins. The dagger grind blade appears to be mostly full, likely 90% or better and the tang is stamped PICKSLAY'S PERUVIAN STEEL SHEFFIELD. The scales appear to be Ivory and are in good condition with a couple of tiny hairline cracks by pins and a small piece missing by the button as you can see in the pics. The knife works well with the blade tip even with the liners closed, good snap and good lockup open with slight movement each way at the tip. Does not rattle if shaken with blade open. Safety is stuck. VG condition for a 200 year old switchblade.