diff --git a/README.md b/README.md
index bdd4141a10e6a4461462dcce0f589fb6b8539494..512c8657ce9366d4ee564b00f2e096c392973791 100644
--- a/README.md
+++ b/README.md
@@ -28,6 +28,7 @@ so we're targeting filter material able to block particles with minimum ~0.25um
 ### conventional test methods
 - Henderson apparatus: generates closed circuit microbial aerosols from a Collison nebulizer at a controlled humidity 
    - Collison nebulizer - generally a pneumatic atomizer [^collisonNebulizer]
+   - ![](henderson_apparatus.png)
 - mobile henderson appartus 1968 [^henderson]
 
 performance difference between pleated hydrophobic filters and electrostatic filters??