Stainless Steel Barograph Pen
Conventional stainless steel triangular-type wet ink barograph nib often used on older barographs, and handmade by Russell Scientific in the UK.
We cannot be certain they fit all or any type of barograph arm but from experience the metalpen has fitted on to practically all old barographs using a single pen. To fit to your barograph simply gently open the small grips to slide over the end of your barograph arm, the nib is then clasped on using a pair of pliers to carefully but firmly close the clasps.
Barograph pens may also be referred to as barograph markers.