Cell type: Selenium
Measure type: reflectance
Camera-wiki says that "Laboratorium Prinsen (LP) was a Dutch company ounded by Frits Prinsen in 1938 in Rotterdam," though they soon relocated to Nijmegen. They made a few box cameras and several light meters, mostly versions of this one, their first.
This one has an unusual design. The high/low light cover is on a hinge. The meter needle has the ƒ/stops marked on it, and the shutter speeds are marked on a ribbon on the far right. The ribbon scrolls by turning the little knurled knob in the lower right side. When the cover is in-place, you see the downward pointing arrow next to the name Prinsen on top, pointing to the left-hand column of speeds; if you flip the cover forward for low light, the arrow on the cover point to the right-hand column of speeds. Pretty nifty.
This is just pre-World War II, so the film speed table on the back is in DIN, European Scheiner and H&D.
There are two plugs on the back so that you could plug in a low-light booster. I don't have the instructions on how to compensate for it.
This meter was a gift from Marcus Rowland. Thank you very much!