Stamped with the Hjorth name at the bottom, hence from 1892 or later. Also made before the little stylized stove was inserted into the text PRI-MUS after 1896. The removable pump tube with its old style NRV also indicates this year to be the last probable one of manufacture. This tube, however, has a hex nut for its removal instead of the slimmer solution you can see on the other 19:th centuries Primuses with this NRV, and its removable pump tube. This is of course also before any model numbers were assigned to the stoves. It has the same feature as all the old Primus stoves, like the text on the pump- and tank lid, no text on the air release screw, the old-style legs with sharply curved pot rests and no "feet" at the bottoms etc. One funny thing worth noticing is that they stamped the tank lid wrong! The 'N' in 'Patent' is mirrored, as you can see in the fourth thumbnail! That's a bit odd, because you can't get a stamped letter wrong so easily. Perhaps they accidentally mixed a cyrillic type into the stamping tool? The export to Russia started as early as 1893, so it's a possibility... The burner is most likely the original, or atleast one of the earliest. It doesn't have the hex nut to help you to fit it to the stove as the later ones has. The flame spreader was missing, so I had to put a later one there instead. Fascinating that they kept the same size and shape for more than a century, so that you still could use quite recent spare part on a late 19:th centuy stove... That goes for more than that particular thing. Many things on the absolute oldest Primuses were still directly exchangeable with some parts as long as the domestic stoves were produced. Now, ain't that a winning design?!