Source: The Painting Of The Ancients, published in 1638
This is an example of a wire watermark, depicting what initially looks like a pot holding three flowers, such as tulips. Upon closer inspection, the element at the bottom is not a pot, but rather a crown. What at first glance appear to be tulip blossoms might actually be intended to represent a 'heart' shape. As the image from another example of this watermark below shows, underneath the crown are two letters: either an "E" or "F" and a "C". This item was found on one of the endpapers for The Painting Of The Ancients, published in 1638, but it was possibly a later addition when the book was rebound.
Additional Book Information
The Painting Of The Ancients, in three Bookes: Declaring by Historicall Observations and Examples, The Beginning, Progresse, and Consummation of that most Noble ART. And how those ancient ARTIFICERS attained to their still so much admired Excellencie. Written first in Latine by Franciscus Junius, F.F. And now by Him Englished, with some Additions and Alterations. (Published at) London: Printed by Richard Hodgkinsonne; and are to be sold by Daniel Frere, at the signe of the Bull in Little-Britain. 1638