Drebbel was an engraver by profession when living in Holland at Haarlem and Alkmaar as a pupil of his brother-in-law, [https://en.wikipedia.org/wiki/Hendrik_Goltzius Hendrick Goltzius].
In the right hand lower corner of Music and Astronomy we see clearly Drebbel’s monograms,
probably the same kind of monograms with which he later hall-marked his instruments.
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