- Date
 - 1669.09.05
 - Ep
 - 41
 - Sender
 - Benedictus Spinoza, de
 - Sent from
 - -
 - Recipient
 - Jarig Jelles
 - Received in
 - -
 - OP NO.
 - XLVI
 - OP PP.
 - 536–8v
 - NS OP.
 - XLVI
 - NS PP.
 - 588–90
 
Annotations
Sketch of a piping system to explain an experiment in the mechanics of fluid dynamics (lost). Perhaps, the letter also contained a drawing of an improvised leverage system. Printed in OP/NS.